Dynamic Electrochemistry: Methodology and Application - Analytical

May 19, 1998 - James L. Anderson is Professor of Chemistry at the University of Georgia. He received his B.A. in chemistry from Kalamazoo College in 1...
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Anal. Chem. 1998, 70, 519R-589R

Dynamic Electrochemistry: Methodology and Application James L. Anderson*

Department of Chemistry, University of Georgia, Athens, Georgia 30602-2556 Louis A. Coury, Jr.

Bioanalytical Systems Inc., 2701 Kent Avenue, West Lafayette, Indiana 47906-1382 Johna Leddy

Department of Chemistry, University of Iowa, Iowa City, Iowa 52242 Review Contents Internet Resources, Books, and Reviews Internet Resources Books Review Articles Mass Transport Analytical Voltammetry General Reviews Cyclic Voltammetry Sinusoidal (Alternating Current) Voltammetry Pulse Voltammetry Stripping Voltammetry Catalytic or Electrocatalytic Methods Microelectrode Arrays Electrochemical Flow Detectors Biosensors Heterogeneous/Homogeneous Kinetics Electroactive Monolayers Electroactive Polymers and Multilayers Heterogeneous Electron Transfer at Coated Electrodes Hydrogen Electrochemistry Oxygen Reduction Heterogeneous Kinetic Studies (Diffusion Systems) Kinetic Studies at Semiconductor Electrodes Theory and Computation Surface Electrochemistry Theoretical Aspects Modified Electrodes Models and Theory Methods Ion-Exchange Polymers Organic Redox Polymers Polymers of Transition Metal Complexes Inorganic Polymers Clays and Zeolites Monolayers Bioelectrochemistry Nitric Oxide Biogenic Amines Glutamate Acetylcholine and Choline Neuroactive Peptides S0003-2700(98)00018-3 CCC: $15.00 Published on Web 05/19/1998

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Glucose Sensors Sensors for Other Small Molecules Flavins and Flavoproteins Cytochromes and Hemes Other Metalloproteins Nucleic Acids and Polynucleotides Immunological Approaches Miscellaneous Characterization of Redox Reactions Spectroelectrochemistry Reviews UV-Visible Reflection and/or Absorption Infrared Reflectance or Absorbance Raman Dimerization Flow Cells Multimode Methods Concentration Gradients Long Optical Path Thin-Layer Spectroelectrochemistry Diffusion Layer Imaging and Concentration Gradient Profiling Chemiluminescence and Luminescence Ellipsometry and Circular Dichroism Surface-Selective Techniques Photoelectrochemistry Oscillations Electron Spin Resonance (ESR) Nuclear Magnetic Resonance Mass Spectrometry Instrumentation General Electrochemical Instrumentation: Hardware Chemometrics and Calibration Electrochemical Cell Designs Electrode Designs Literature Cited

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Dynamic electrochemistry generally refers to that subset of electrochemical systems in which a clear equilibrium is not established. Topics such as voltammetry, amperometry, coulometry, chronopotentiometry, and electrochemical impedance spectroscopy fall naturally into this category. These techniques share the common feature of involving the imposition of a potential or

© 1998 American Chemical Society

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current program, resulting in a response (transient and/or steady state) by the system that may be measured and recorded. In this review, the operational definition of dynamic electrochemistry will be broadened somewhat from the above to include studies that involve dynamic processes at some stage in the experiment (i.e., current may flow during the experiment, although not necessarily at the time of measurement). For example, some spectroelectrochemical experiments operate under less than fully dynamic conditions during measurement but involve prior dynamic processes that transform the analyte into the species actually measured (e.g., coulometry followed by spectrophotometric measurement). Thus, the above definition will be used as a guideline for this review, not as a rigorous set of limits. Techniques such as potentiometry, in which little to no departure from equilibrium occurs, although important, are not included here. Spatially selective measurement and mapping of interfaces is an important trend in electrochemistry. However, some scanning probe microscopy (SPM) experiments fall outside the scope of this review, despite the fact that they involve measurement of current/potential relationships. Exceptions to this include SPM studies with a focus on measurement of a dynamic process, such as current flow, yielding electrochemical information about an interface. Similarly, studies with a focus on mass transport or interfacial redox behavior as probed by scanning electrochemical microscopy are deemed to be more electrochemistry than microscopy and will be included. Articles published during the period extending roughly from October 1995 through October 1997 are considered by this review. Extensive use has been made of electronic search tools to locate citations, particularly Chemical Abstracts searches. Absolutely no attempt has been made to provide comprehensive coverage of the literature in this area. Inevitably, many good papers will not be cited. As in previous years, a critical assessment has been made of the literature, and attempts were made to cite reports of the most novel, significant, and/or fundamental advances. Review articles and books discussed are the most inclusive and representative of the field. Obviously, many other useful and interesting works have necessarily been omitted to keep this review (somewhat) manageable in size. As may be seen from the review contents, above, the present article somewhat resembles its immediate predecessor (A1) in terms of the broad grouping of topics. Both subjects of clear analytical relevance (e.g., amperometric sensors, flow cells) as well as more fundamental topics (interfacial redox reactions of self-assembled monolayers, kinetic and mechanistic studies, new spectroelectrochemical techniques) will be covered. However, in a break with tradition, citations to sources of information on the Internet are now included. References to such electronic media are made in the body of this review in a manner analogous to those for printed media. In the Literature Cited section, the uniform resource locator (URL) format has been used to facilitate linking to these sites by those readers who subscribe to the electronic version of Analytical Chemistry. These links were verified to be current and accessible by the authors of this review as of January 1998. The inclusion of Internet resources in this review pointedly illustrates one of the major trends in activity since the last review in this series. Use of the Internet and especially the World Wide 520R

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Web (WWW) for accessing and sharing information among electrochemists has grown explosively. Some other areas of recent activity emphasized here include the electrochemical construction and characterization of nanometer-sized structures, the widespread use of sophisticated simulation programs for the analysis of complicated electrochemical systems, single-molecule detection by electrochemical means, and increased use of modern electrochemical techniques by biologists and material scientists. Electrochemical topics with a strong polarization toward technological applications (e.g., corrosion studies, enhancement of fuel cell performance, improvements in battery design) are not a focus of this review, although they are of undeniable importance and economic impact. Review articles on the use of dynamic electrochemical methods to facilitate research in each of these areas of technology, however, are mentioned here and should provide a helpful entry into the literature of these separate disciplines. Some papers in these areas will also be cited for other reasons throughout the review (e.g., a new spectroelectrochemical approach, or a new simulation or model, which happens to be applied to a problem that falls within these broad subject areas). INTERNET RESOURCES, BOOKS, AND REVIEWS Internet Resources. Electrochemical information available over the Internet, particularly on the World Wide Web, has increased in amount and quality over the past few years. This information is accessible through several different mechanisms and in a variety of formats. Unlike printed matter, however, the continuing availability of these items is often uncertain. Web sites change (or even disappear) without notice, and articles posted to news groups expire after a length of time set by the system administrator maintaining the particular news server being accessed. Despite these uncertainties, retrieval of information over the Internet has become a much relied-on method for the scientific community. Thus, in a departure from preceding reviews (A1), this review article will include citations to Web sites and other Internet resources of interest to electrochemists. (a) Comprehensive Web Sites. There are many interesting and high-quality Web sites associated with electrochemistry research groups, organizations, and companies around the world. It is well beyond the scope of this review to discuss these sites in any detail, but they may be easily located using one of the many popular Web search tools. However, a few examples of the types of information available on the Web will be given below. Perhaps the most comprehensive and detailed source of electrochemical information on the Internet is the series of files maintained by Dr. Zoltan Nagy, referred to collectively as the Electrochemical Science and Technology Information Resource, or ESTIR (A2). This site is not a repository for primary data, but rather includes several independent compilations that may well constitute the world’s most useful entry into the electrochemical literature. One of the files is a comprehensive list of books on electrochemistry, broadly defined, that includes author(s), publisher, and year of copyright for each entry. As far as can be determined, all electrochemistry texts, monographs, and multiauthor books published since 1950 in the English language are included here listed in chronological order. Other ESTIR files include similarly comprehensive lists of electrochemistry review articles, and proceedings volumes from electrochemistry-related

Table 1. Web Sites for Electrochemistry Organizations I. Multinational Electrochemistry Web Sites The Electrochemical Science and Technology Information Resource http://electrochem.cwru.edu/estir/ The Electrochemical Society http://www.electrochem.org/ Federation of European Chemical Societies, Working Party on Electrochemistry http://www.rsc.org/lap/fecs/fecs•e.htm International Society of Electrochemistry http://www.access.ch/ise/ International Union of Pure and Applied Chemistry, Electrochemistry Commission http://www.rsc.org/is/iupac/iupac•cs.htm II. Electrochemistry Divisions of National Societies Australia: The Royal Australian Chemical Institute, Electrochemistry Division http://www.raci.org.au/divisions/electro/ Austria: Gesellschaft O ¨ sterreichischer Chemiker, Arbeitsgruppe Elektrochemie (Austrian Chemical Society, Electrochemistry Working Group) http://ping.at/goech/ags/ags.htm Brazil: Sociedade Brasileira de Quı´mica, Divisa˜o de Eletroquı´mica e Eletroanalı´tica (Brazilian Chemical Society, Division of Electrochemistry and Electroanalysis) http://www.sbq.org.br/DIV-EQ/divisao.htm France: Socie´te´ Franc¸ aise de Chimie, Groupe Electrochimie (The Chemical Society of France, Electrochemistry Group) http://www.sfc.fr/Activites•groupes/Electrochimie/ele2•groupe•electrochimie.htm Germany: Fachgruppe Angewandte Elektrochemie der Gesellschaft Deutscher Chemiker (Section for Applied Electrochemistry of the Society of German Chemists) http://www.gdch.de/fachgrup/elektro.htm Great Britain: Electrochemistry Group of the Royal Society of Chemistry http://www.rsc.org/lap/rsccom/dab/fara005.htm Italy: Societa´ Chimica Italiana, Divı´sione di Elettrochimia (Electrochemical Division of the Italian Chemical Society) http://www.xmission.com/∼gastown/chemistry/dde.htm

conferences. Also located at this site is a worldwide directory of graduate programs and research groups specializing in electrochemical science, as well as a detailed list of announcements of up-coming meetings of interest to electrochemists. Finally, a file with answers to frequently asked questions (FAQ) from the electrochemistry news group news://sci.chem.electrochem is included. This file contains a wealth of information including (but not limited to) the following: (i) a list of all known electrochemistry journals, (ii) pointers to public domain software and databases available over the Internet, (iii) information on various technical societies, and (iv) citations for articles published in the popular press on electrochemical topics. The latter is a tremendous resource for secondary school teachers and those engaged in chemistry outreach programs. The news group from which the FAQ is derived (as well as its younger sibling news:/ /sci.chem.electrochem.battery) is highly recommended as a medium for discussion of topics of interest to electrochemists. For those without access to a news server, the same information is available by e-mail through subscription to the mailing list ELETQM-L. Instructions for subscribing to the list are available at ESTIR in the file FAQ.TXT. The information housed in ESTIR may be accessed from the WWW by using a Web browser set to the URL http://electrochem.cwru.edu/estir/. Alternatively, the files may be retrieved using file-transfer protocols (anonymous ftp) from ftp://electrochem.cwru.edu. These sites are hosted by the Yeager Center for Electrochemical Science at Case Western Reserve University, and together with Dr. Nagy, they are to be congratulated on realization of a unique achievement. (b) Society Web Sites. In addition to the American Chemical Society (A3), several more specialized societies of particular interest to electrochemists actively maintain a Web presence. Table 1 lists a few representative sites and their URLs. Note that an exceptionally detailed and comprehensive list of Web sites for technical and scholarly societies is maintained at the University of Waterloo (A4). This database lists the URL for each society,

in addition to a parameter for each site called the stability index. The latter has been determined from the format of each URL in an attempt to predict those most likely to change. Organizations that establish new Web sites are urged to follow the naming conventions that are recommended by the Waterloo group. (c) Web Sites for Electrochemistry Journals. Traditionally, the primary mechanism for timely sharing of information among scientists has been the scientific journal. It has clearly been a high priority for the ACS to develop and provide access to electronic versions of its journals, and as of January 1998, Web versions of 26 popular ACS journals were available by electronic subscription. Novel issues must be addressed as the publishing world struggles through the transition from print to electronic media. Such topics as continuing assurance of quality control (peer review) and lack of access to back “issues” of journals once an electronic subscription is discontinued are major concerns. A stimulating discussion along these lines published on the ACS Publications Web pages is recommended reading (A5). Despite a lack of resolution with respect to these points, electronic publishing is already a reality, and Web sites for some journals of interest to electrochemists may be found in Table 2. In most cases, the tables of contents for the journals are freely made available. Entries in this table are limited to journals with a substantial focus on the field of electrochemistry. General analytical journals, for example, were excluded. (d) Commercial Web Sites. A number of companies involved in providing electrochemical equipment and services have useful Web sites. Many of these pages provide access to technical bulletins and notes covering various electrochemical techniques and applications. Table 3 presents a list of examples falling into this category. Of particular note among these sites, Analyticon maintains a registry of equipment suppliers; the Bioanalytical Systems site will run a digital simulation demonstration to illustrate the concept of kinetic (ir-)reversibility; Gamry has developed an interactive conferencing center for worldwide exchange of expertise; Pine provides a laboratory experiment for educators that Analytical Chemistry, Vol. 70, No. 12, June 15, 1998

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Table 2. Web Sites for Electrochemistry-Related Journals Current Separations http://www.bioanalytical.com/csindex.html Electroanalysis http://www.nmsu.edu/∼chemdept/sensors/journal/editor.html The Electrochemical Society (a) Journal of the Electrochemical Society http://www.electrochem.org/journal.html (b) The Electrochemical Society Interface http://www.electrochem.org/interface.html Elsevier Science (a) Electrochemistry On-Line Service http://www.elsevier.com/inca/homepage/saa/jecos/menu.html (b) Bioelectrochemistry and Bioenergetics http://www.elsevier.com/inca/homepage/saa/jecos/biojec/ (c) Biosensors & Bioelectronics http://www.elsevier.com/inca/homepage/saa/jecos/biosensors/ (d) Electrochimica Acta http://www.elsevier.com/inca/homepage/saa/jecos/eca/ (e) Journal of Electroanalytical Chemistry http://www.elsevier.com/inca/homepage/saa/jecos/jec/ (f) Journal of Power Sources http://www.elsevier.com/inca/homepage/saa/jecos/power/ (g) Sensors and Actuators B: Chemical http://www.elsevier.com/inca/homepage/saa/jecos/snb/ Journal of Applied Electrochemistry http://www.chapmanhall.com/ja/jatext.htm Journal of New Materials for Electrochemical Systems http://www.polymtl.ca/journal/material.html

compares three electrochemical methods for determination of diffusion coefficients; Scribner offers free impedance software that can be downloaded via the Web. Books. Several books of interest to the electroanalytical community have appeared since the last review. A second edition of Kissinger and Heineman’s Laboratory Techniques in Electroanalytical Chemistry was published in 1996 (A6). This multiauthor book is billed by its editors as a text/reference, which accurately describes its scope. Several introductory chapters present fundamental concepts of dynamic electrochemistry (kinetics, mass transport) without extensive mathematical treatment and thus may be useful as a course text. The subsequent chapters provide a tremendous amount of practical information relevant to contemporary research. Areas covered by the second edition that were not dealt with extensively in the first version include construction and properties of microelectrodes, characterization of chemically modified electrodes, electroorganic synthesis, low-temperature electrochemistry, and interfacial redox reactions in molten salts. In addition, most of the other sections have been extensively reworked. For example, the chapter on electrochemical detectors for liquid chromatography has been expanded to encompass capillary electrophoresis experiments. Also useful as textbooks are two new members of the Oxford Chemistry Primers series. Both Fisher’s Electrode Dynamics (A7) and Compton and Sanders’ Electrode Potentials (A8) admirably achieve the stated goals for the series by providing a concise introduction to an area of importance to all chemists. A book by LaCourse on pulsed electrochemical detection in HPLC (A9) will be of interest to electroanalytical chemists. Applications in bioanalytical chemistry are a substantial focus of this book, which could be suitable for use as a textbook for a special topics course. Volume 139 in the long-standing Wiley series Chemical Analysis focuses broadly on modern electroanalytical techniques (A10). Included in this multiauthor volume edited by Petr Vany´sek are chapters on vacuum, infrared, and scanning probe methods for 522R

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Table 3. Representative Commercial Electrochemistry Web Sites Amel Instruments http://www.amelsrl.com/ Analytical Instrument Systems http://www.aishome.com/ Analyticon Instruments Corp. http://www.analyticon.com/ AndCare http://www.andcare.com/ Arbin Instruments http://www.arbin.com/ Axon Instruments http://www.axonet.com/pelectro.htm Bioanalytical Systems http://www.bioanalytical.com/ Bio-Logic http://www.bio-logic.fr/ Cypress Systems http://www.cypresshome.com/ Eco Chemie/Autolab http://www.ecochemie.nl/ EG&G Princeton Applied Research http://www.egginc.com/bin/webmate/Inst|139/page/egg/frame Electrosynthesis Co. http://www.electrosynthesis.com/ Eltron Research http://www.sni.net/eltron/ Gamry Instruments http://www.gamry.com/ Metrohm http://www.gemini.co.uk/biopages/co/metro/metro02.html Pine Instruments http://www.pineinst.com/echem/echem.htm Scribner Associates http://www.scribner.com/ Solartron Instruments http://www.solartron.com/ Sycopel Scientific http://www.sycopel.com/ World Precision Instruments http://www.wpiinc.com/ Zahner Messtechnik http://www.zahner.de/imp/imp.htm

examining electrochemical interfaces. In addition, a chapter by the editor himself on liquid-liquid electrochemistry is highly recommended. The 19th volume of Bard and Rubinstein’s Electroanalytical Chemistry is composed of three lengthy reviews (A11). Speiser contributes a chapter on numerical simulations in electrochemistry, Finklea discusses the electrochemistry of thiol-based monolayers, and McDevitt and colleagues present an analysis of the electrochemistry of high-Tc superconducting phases. In a more physical vein, Schmickler’s monograph Interfacial Electrochemistry is of particular note (A12). Divided into three parts, fundamental topics are presented first. This section is followed by a survey of relevant experimental techniques and finally, some topics of special interest to theorists are discussed (including charge distribution in adsorbates and quantum theory of electron-transfer reactions). The physical processes underlying metal deposition are treated in a unique book by Budevski, Staikov, and Lorenz (A13). Topics covered include electrocrystallization and underpotential deposition reactions. Fundamentals of processes occurring at interfaces are also the focus of the 656th installment of the ACS Symposium Series (A14). Entitled SolidLiquid Electrochemical Interfaces, this member of the series is composed of 23 chapters discussing LEED, AES, XPS, STM, and AFM studies of electrode surfaces.

A sixth issue in the series Topics in Current Chemistry that is devoted to electrochemistry is now available (A15). Edited by Steckhan, this volume examines electrochemical techniques for the formation of carbon-carbon and carbon-heteroatom bonds. The preparation of pharmaceuticals, the electrosynthesis of peptide mimics, and the comparative advantages of electroorganic techniques to conventional methods are discussed. The fifth volume of Advances in Electrochemical Science and Engineering was also published in 1996 (A16). It contains a review of Marcus theory as applied to electrochemiluminescence, in addition to chapters on fuel cells, metal-free batteries, and the electrochemistry of oxide-containing, high-Tc superconductors. New volumes in the series Modern Aspects of Electrochemistry have recently appeared at a bewildering pace. No less than five new members of the series were published since the last review (volumes 27-31), and unfortunately, the numerous constituent chapters were not grouped into volumes according to their subjects. Readers who desire more details on this series are referred to the publisher’s Web site (A17), which contains a list of the more than 30 chapter titles and authors for the above volumes. Also published by Plenum is the second part of a series devoted to the electrochemistry of electroactive polymers (A18). Edited by Lyons, the latest volume covers diverse topics ranging from theoretical calculations and numerical simulations to the application of polymer-coated electrodes in sensor construction. A chapter by Kelly and Vos on Os and Ru poly(pyridyl) polymers is also noted. The publication of monographs on the subject of biosensors has continued at a tremendous rate. A few examples of texts that distinguish themselves from the rest of the herd include a recent book by Kress-Rogers that places biosensors in the context of the electronic nose (A19). Starting from a review of the categories and principles of operation of common sensors, moving through the concepts of receptors and membranes, the book builds to a discussion of approaches for mimicking the human olfactory system. Environmental applications are discussed in this book as well. That subject is more fully developed in an ACS Symposium Series volume with a specific focus on the uses of biosensors in environmental monitoring (A20). Another recent biosensor book that emphasizes electrochemical approaches was written by Eggins. It is noteworthy for the inclusion of laboratory experiments (A21). Last, two new volumes in the series Bioelectrochemistry: Principles and Practice became available during the review period. Volume 3, entitled Experimental Techniques in Bioelectrochemistry, discusses electrochemical impedance spectroscopy, voltammetry, and spectroelectrochemistry as a basis for studying biomolecules in solution and at interfaces (A22). Volume 4 (Bioenergetics) has a substantially different focus and discusses the electrochemistry (energetics, kinetics, mechanisms) of photosynthetic reactions (A23). Review Articles. We next turn our attention to individual articles that summarize or critically examine previously published information. Due to the vast number of examples, articles from conference proceedings will generally not be included here. Note, however, that many of the volumes published by the Electrochemical Society (ECS) contain very useful reviews of specific areas, often written by organizers of ECS symposia. In the period

covered by the present review, over 50 volumes spanning the entire range of interests of the ECS were published. Readers are encouraged to visit the ECS Web site (http://www.electrochem.org/books.html) for more information on these items. (a) Single-Molecule Detection. A continuing theme in electroanalytical chemistry for many years has been the gradual improvement of detection limits. A recent review by Bard and Fan focuses on the ultimate and inevitable culmination of such studies: the use of scanning electrochemical microscopy (SECM) for the detection of a single molecule (A24). Rather than representing the end of a long-standing stream of activity, however, this paper points out an entirely new set of research questions that this technology may be utilized to address. A few examples mentioned include testing probability models for sampling such small volumes, examining the validity of conventional assumptions about electroneutrality, and extracting kinetic parameters for coupled interfacial/solution reactions involving a single electroactive molecule. (b) Microscopies. In addition to single-molecule detection, the SECM technique can be used in a variety of experiments, as pointed out by five additional review articles on this topic (A25A29). Other high-resolution microscopy techniques are recognized as being useful for electrochemical studies. For example, Gewirth and Niece (A30) give a comprehensive discussion of the electrochemical applications of scanning tunneling (STM) and atomic force microscopies (AFM). Similar ground is covered by Kolb and colleagues (A31), Ge and Thornton (A32), and Li and Wang (A33). In a more specialized article, Kurochkin (A34) describes STM and AFM studies of protein Langmuir-Blodgett films. Applications of in situ STM in semiconductor electrochemistry are surveyed by Allongue (A35). (c) Characterization of Interfaces. The inclusion of scanning probe microscopies as one member of a family of techniques used together for in situ characterization of interfaces is the subject of an interesting review by Peter (A36). In a paper by Adzic and colleagues, the complementary nature of data from surface X-ray scattering and STM is discussed (A37). This idea of combining information gained by several techniques is developed within the specific context of investigations of passivity in an account by Schultze and Kudelka (A38). The value of in situ, microscopic-level techniques applied toward understanding the structural properties of monocrystalline metal-solution interfaces is the subject of an article by Weaver (A39). Results from scanning probe microscopy, quartz crystal microbalance studies, FT-IR, and X-ray methods are examined together in a discussion of polycrystalline copper electrodes by Kautek et al. (A40). The use of in-situ spectroscopic measurements for examination of various interfaces is similarly reviewed by Holze (A41). Infrared methods are of particular value in fundamental interfacial studies as discussed in contributions from Villegas and Weaver (A42) and Korzeniewski (A43). Combined use of IR and UV methods specifically for corrosion studies is the subject of a review by Beden (A44). Characterization of solidliquid interfaces by sum-frequency spectroscopy is discussed by Bain (A45). This nonlinear optical technique can be used to generate vibrational spectra of molecular species adsorbed at interfaces. Analytical Chemistry, Vol. 70, No. 12, June 15, 1998

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Several reviews provided informative overviews of other approaches for interfacial studies. By employing radiolabeled species, adsorption phenomena at rough and smooth polycrystalline electrodes and at well-defined single-crystal surfaces can be studied. The use of such radiochemical experiments for interfacial studies is discussed by Wieckowski and colleagues (A46) and by Horanyi (A47). Solid-state NMR is a powerful technique in chemical analysis, but it has only been applied to electrochemical systems fairly recently. An interesting paper discussing progress in the use of NMR to study molecules adsorbed onto metal surfaces while under potentiostatic control (in the presence of electrolyte) will be of wide interest to electrochemists (A48). The principles of operation of the Kelvin probe may not be as familiar as NMR to many chemists. An informative paper by Janata and Josowicz on this topic (A49) is recommended. Spatial mapping with the Kelvin probe is reviewed by Stratmann and Furbeth (A50). In particular, measurement of corrosion potentials through insulating polymer films is described. A photoelectrochemical approach to surface analysis was reviewed by Burleigh (A51). In the experiment described, pulsed UV or visible light strikes an electrolyte-immersed metal electrode. Absorption of the light by surface oxygen species (oxide or hydroxide) generates a weak photocurrent that can be used as a “photosignature” of the surface film. Surface conductance is another physical parameter that can be measured to gain insight about the chemical state of an electrode surface, and this type of measurement is discussed by Tucceri and Posadas (A52). (d) The Double Layer and Related Topics. Next, we consider physically oriented reviews of interfacial subjects that do not focus on a particular experimental technique. An article by Parsons considers the current state of knowledge about the metal-liquid electrolyte interface (A53). Topics discussed include the charge distribution on adsorbates and the direct measurement of surface stress on solid electrodes. A paper by Trasatti and Doubova explains the effect of the crystallographic orientation of a metal surface on double-layer parameters (A54). Effects on the potential of zero charge (and its temperature coefficient), the interfacial capacitance, and the adsorption behavior of the surface are covered. Fawcett reviews solvent effects in simple electrontransfer reactions (A55). Difficulties in estimation of outer-sphere activation free energies are addressed, and data for the reduction of hexaaquoferrate (III) at single-crystal gold are considered. A critical discussion of progress made during the past decade toward applying quantum chemical calculations of varying levels of approximation to electrochemical problems was published by Nazmutdinov and Shapnik (A56). The applicability of cluster models to the description of macroscopic double-layer phenomena is assessed in this article. A paper by Halley observes that the interdependence of electronic and atomic structure and dynamics poses a severe challenge for conventional theory and simulation techniques (A57). To illustrate this point, two methods applied to oxide-water interfaces are compared. A self-consistent, tightbinding method applied to the surface of a rutile phase is presented. This is followed by the elaboration of a polarizable, dissociable model of the water-iron(III) hydroxide interface. A review by Pajkossy describes the generalization of electrochemical theories to fractal surfaces (A58). The kinetics of diffusion to 524R

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fractal surfaces is treated, and the impedance of fractal capacitive electrodes is described. Some aspects of the electrochemical behavior of Pt single crystals in alkaline electrolytes are reviewed by Aldaz et al. (A59). Discussion is made of the controversies surrounding the assignment of voltammetric features observed for Pt(111) in basic media. The oxidation of CO, glucose, and formaldehyde on both reconstructed and unreconstructed Au(100) is compared by Thompson (A60). Change from a closed hexagonal phase to a more open fcc phase is noted. The phenomenon of negative differential capacitance in certain systems has been examined in a review by Partenskii and colleagues (A61). Surface phase transitions are implicated here, and differences between systems under charge and potential control are emphasized. (e) Adsorption Phenomena. The adsorption behavior of aromatic compounds at mercury electrodes has been successfully related to the electronic properties of these molecules when “isolated”, in a paper by Benedetti and Fontanesi (A62). Reactivity indexes describing the formation of the Hg-adsorbate couple are included in this model. A paper of interest to students of the history of electrochemical surface science should be mentioned. Stradins has written a review of the scientific contributions of A. N. Frumkin (A63) which also traces the evolution of the field of theoretical electrochemistry. (f) Liquid-Liquid Interfaces. The subject of electrochemical processes at liquid-liquid interfaces merited a number of recent reviews. Perhaps the best entry into the literature of this fascinating area is a review by Vany´sek that summarizes progress made in this field over the past 100 years (A64). Two reviews by Kihara appear to overlap somewhat in coverage (A65, A66). Each review treats ion transfer through a bilayer lipid membrane as an ion transfer at the interface between two immiscible phases. The use of second harmonic generation to probe liquid-liquid interfaces is evaluated by Brevet and Girault (A67). Liquid-liquid interfaces as applied to the design of artificial photosynthetic systems are discussed by Volkov and associates (A68). Finally, a review by Senda discusses, among other topics, the use of amperometric sensors for monitoring ion-transfer reactions at the interface between two liquids (A69). (g) Organized Media. Electrochemistry in organized media was reviewed from a number of different angles. Electron-transfer reactions at electrodes in micellar solutions was treated by Rusling (A70). Microemulsions are related systems, prepared by mixing water, oil, and a surfactant. Electrocatalytic reactions employing cobalt complexes (vitamin B12) as mediators in these media were evaluated for their synthetic utility by Rusling et al. (A71). An interesting variation on the theme of electrochemistry in surfactant-containing solutions was reported by Abbott (A72). In this work, the surface tension of an aqueous solution was reversibly modulated through oxidation and then reduction of soluble, cationic surfactants bearing a pendant ferrocene moiety. The use of cyclic voltammetry to gain information about such heterogeneous systems was the subject of a report by Rusling and Suib (A73). In a more electroanalytically focused article, Talbot and colleagues compare various electrochemical techniques for the detection of surfactants (A74). Tensammetry, electrocapillary measurements, potentiometry, and biosensors are each consid-

ered, in addition to standard dynamic techniques such as voltammetry and amperometry. Two reviews dealt with the topic of amphiphiles directly on electrode surfaces. Rusling’s article has a substantial focus on the reactions of biomolecules at protein, surfactant, and polyelectrolyte-coated electrodes (A75). Bizzotto and Lipkowski discuss the transfer of surfactant monolayers onto a single-crystal gold electrode (A76). They demonstrate that the adsorption of micelles onto a gold surface is potential dependent. In a similarly physical vein, the processes of translational diffusion and electron hopping through monolayers at an air-water interface is treated by Majda (A77). (h) Self-Assembled Monolayers (SAMs). A tremendous amount of effort over the past few years has focused on the construction and characterization of ordered, nonpolymeric films on electrode surfaces. An overview of promising approaches for the design of this type of chemically modified surface is the subject of an A-pages article by Zhong and Porter (A78). Both LangmuirBlodgett procedures and spontaneous assembly are described. A review by Mandler and Turyan discusses the applications of SAMs in electroanalytical chemistry (A79). Bilewicz emphasizes SAMs that serve as diffusion barriers to solution species as well as those with built-in channels and binding sites (A80). Two reviews by Kaifer summarize progress in the design of mono- and multilayer assemblies having preformed binding sites (A81, A82). An account by Abrun ˜a and colleagues summarizes their successes in synthesizing and characterizing SAMs functionalized with Ru, Os, Co, and Cr complexes (A83). A report by Fox et al., is concerned with combined electrochemical and photochemical experiments on SAMs (A84). In these experiments, thiols modified with electrophores or chromophores are examined, and tunneling efficiency and the photosensitivity of pendant groups correlates well with surface packing. Smalley et al. report the use of a laser-induced temperature jump technique to examine ferrocene-terminated, thiol-based SAMs (A85). Last, a review by Ottova and Ti Tien on self-assembly of bilayer lipid membranes (BLMs) is recommended (A86). Nearly 100 references to work with BLMs are listed, including a survey of the wide variety of substrates onto which these films have been deposited (e.g., Pt, stainless steel, copper, porous filters). (i) Electronically Conducting Polymers. A number of new reviews discuss progress made in the elaboration of highmolecular-weight organic films that exhibit electronic conductivity. A multitude of functional groups can be added to the basic pyrrole unit, and Deronzier and Moutet summarize the possibilities (A87). Although sometimes referred to as synthetic metals, these conducting polymers are more closely related to semiconductors in their electronic properties. A paper with 402 references by Roncali sets down the synthetic principles useful for control of the band gap in linear (polymeric) π-conjugated arrays (A88). Lending further weight to the above semiconductor analogy, a paper by Kazarinov et al. summarizes kinetic results at the polymer-solution interface (A89). The authors conclude that electronically conducting polymers may behave variously like metal phases, semiconductors, or insulators in their electrontransfer behavior, depending on the nature of the dopants present and the dopant density.

Two reviews with a synthetic flavor are likely to be of interest to electroanalytical chemists. Deronzier and Moutet discuss the synthesis of poly(pyrrole) films containing metal complexes (A90). Their review contains 152 references and deals with applications in electrocatalysis, electroanalysis, and photoelectrochemistry. Audebert and Hapiot review data from short time-scale electrochemical studies to elucidate the polymerization mechanism for pyrroles and thiophenes (A91). They implicate π-dimers present in solution near the electrode surface in the early steps of the reaction mechanism. A more general review of conjugated polymer systems and their electrochemical applications is provided by MacDiarmid and Zheng (A92). The analytical utility of electrodes coated with conducting polymers is the subject of two reviews (A93, A94). The first discusses the use of these surfaces as amperometric and potentiometric detectors in flow experiments. The second includes information about incorporation of conducting polymers into sensors for immunoassays. Conducting polymers are also finding use in the construction of sensors for environmental monitoring. Wallace discusses this particular application in his paper (A95). (j) Other Modified Electrode Reviews. The general area of chemically modified electrodes continues to expand rapidly in scope. This growth has created some inconsistencies in terminology that can cause problems (making efficient electronic database searching during the preparation of reviews, for example, quite difficult!). A paper by Durst et al. addresses these difficulties and proposes a consistent nomenclature (A96). A number of reviews have appeared that give coverage to specific types of chemically modified electrodes (CMEs) other than the π-conjugated systems discussed separately, above. Trace analysis with ion-exchange polymer-coated electrodes was reviewed by Ugo and Moretto (A97). The use of ion-exchange polymers for electroanalysis in nonconducting media is covered in another review (A98). Applications of perfluorosulfonated polymers in solid-state electrochemistry are discussed by Bettelheim et al. (A99). When a cation-exchanging membrane is joined to an anion-exchange polymer, a membrane called a bipolar ion exchanger is formed. The electrochemical properties of these systems have been reviewed by Mafe and Ramirez (A100). While not modified electrodes, per se, the unusual characteristics of such systems will be of interest to those working in the CME field. In particular, the electric field-enhanced dissociation of water that occurs at the interface between the two exchange membranes warrants continuing study. Audebert discusses polymer films with a pendant metal atom from the main polymeric backbone, polymers incorporating metallic nanoparticles, and polymers in which a metal is incorporated into the main chain (A101). Salmon and Aguilar focus on properties of films of electropolymerized, asymmetric, heterocyclic chiral monomers (A102). Platinum modified with adatoms (A103), zeolite-modified electrodes (A104), and nucleic acidmodified mercury electrodes (A105) each received attention recently, as well. Films of proteins adsorbed on electrodes are useful for understanding the redox dynamics of metalloproteins as pointed out by Armstrong et al. (A106). Bedioui et al. discuss electropolymerized porphyrin films in biomimetic electrooxidations (A107). Analytical Chemistry, Vol. 70, No. 12, June 15, 1998

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The value of metalloporphyrin-modified electrodes for detection of nitric oxide is assessed in a broader review of the various electrochemical approaches to detection of NO by Bedioui et al. (A108). Finally, two papers discussing the use of the quartz crystal microbalance in CME studies (A109, A110), as well as an apparently extensive and general review of CMEs (for which an abstract was unfortunately unavailable) are noted (A111). (k) Electroanalysis in Flow Streams. A general opinion of the present state of electroanalysis was published by Kissinger and colleagues (A112). They make the point that electrochemists should pay more attention to critically comparing the performance of new techniques they develop against existing chromatographic and spectroscopic approaches. Moeller and Scholz discuss the advantages and limitations of the combination of separations techniques with voltammetry (A113). Along the same lines, Buchberger poses the question of whether electrochemical detectors are tailor-made for HPLC and capillary electrophoresis (CE) (A114). Voltammetric detection in flow analysis using electrocatalytic systems is discussed by Budnikov (A115). Single electrodes are compared to coulometric arrays as detectors in HPLC experiments by Acworth and Bowers (A116). Weber and associates review electrochemical detection in both HPLC and CE (A117), while an article by O’Shea focuses specifically on CE (A118). Kissinger has written a general review of electrochemical detection in bioanalytical chemistry (A119). Topics covered include detection schemes for microdialysis and ultrafiltration, microbore liquid chromatography, capillary electrophoresis, and use with postcolumn reactors based on enzymatic and photochemical processes. Kauffmann discusses electrochemical detectors useful in pharmaceutical analysis in two different reviews (A120, A121). An article by a group at Glaxo Wellcome illustrates the use of cyclic voltammetry to optimize electrochemical (EC) detection in pharmaceutical analysis (A122). They present several case studies in the use of HPLC-EC in supporting preclinical and clinical drug development programs. Finally, Davies and Hounsell discuss EC and fluorescence detection in carbohydrate chromatography and electrophoresis (A123). (l) Stripping Analysis. Chemical and electrochemical preconcentration steps preceding electroanalysis (“stripping”) are widely used strategies for the improvement of detection limits over conventional methods. Fogg has summarized the nomenclature specific to this field (A124), and Bond and associates have reviewed the existing procedures for determining limits of detection and quantitation in stripping analysis and voltammetry (A125). They propose an improved procedure for determining these figures of merit based on a statistical approach involving confidence intervals related to the t-distribution. Various applications of stripping experiments have been reviewed. Anodic stripping voltammetry is useful for studying trace metal complexation in seawater (A126). Bott discusses the voltammetric determination of environmental trace metals (A127). Sample pretreatment and speciation issues are covered in his article. Use of a technique dubbed differential chronoamperometry in conjunction with stripping voltammetry is advocated by Kheifets and Vasyukov in studies of hydroecosystems (A128). A combined review of classical dry ashing procedures and stripping techniques for trace element analysis of biological materials 526R

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appeared in Talanta (A129). Stripping experiments play a prominent role in a review of methods for determination of precious metals (A130). Tur′yan provides a review with 100 references of nonflow cells with volumes as low as 5 µL that are useful for stripping experiments (A131). Zhou discusses the combination of on-line stripping analysis with inductively coupled plasma (ICP) atomic emission (AES) and ICP-mass spectrometry instruments (A132). A number of advantages of such an approach are cited, including diminution of the severity of matrix effects in ICP-AES and the speciation (oxidation state) information that is available from the incorporation of an electrochemical stage in the analysis. Finally, two reviews on adsorptive and cathodic stripping methods are noted (A133, A134). (m) Impedance and Noise Analysis Methods. Sinusoidal modulation of the applied potential is among the oldest of the more complex electroanalytical methods. The use of these ac methods has traditionally been hampered by the length of time required for collection of data and by the difficulties in interpreting results in terms of physically meaningful models. This picture has changed somewhat in recent years due to the availability of instrumentation with multiplexing capabilities and due to the appearance of more sophisticated data fitting and analysis software. To date, the acceptance of these methods in the engineering and applied technology communities has been more rapid than in the chemical measurement arena. However, as more electrochemists begin to understand and use these techniques, their popularity will undoubtedly continue to grow. Most of the reviews listed below summarize the use of impedance methods in an applied area (corrosion, semiconductors, coatings) but will be of interest to chemists as an illustration of the power of this family of techniques. An excellent review of electrochemical impedance spectroscopy (EIS) has been published by Urquidi-Macdonald and Egan (A135). Their paper critically reviews the types of problems well suited for analysis by EIS. This is followed by a brief description of the experimental procedure for implementation of the technique, and then by a discussion of Kramers-Kronig transforms to validate EIS data. Finally, a neural network approach for extrapolation of data over extended frequency ranges is discussed. One of the strengths of the EIS approach is the ability to readily separate and quantitate various impedances (e.g., solution resistance vs charge-transfer resistance) during the data analysis. For this reason, EIS is often used to evaluate the integrity of resistive coatings on metal surfaces, and a review of the EIS literature for following degradation of polymer-coated metals has been provided by Amirudin and Thierry (A136). Nondestructive monitoring of the extent of corrosion of metal reinforcements in concrete structures is another successful application of EIS. This area was recently reviewed (A137) and EIS was critically compared to other electrochemical techniques in this context (half-cell potential mapping, electrical resistance, electrochemical noise, polarization resistance measurements). The use of EIS in semiconductor electrochemistry is well established. The characterization of the semiconductor-electrolyte interface, study of mechanisms of electrochemical reactions, and optoelectronic admittance characterization of photoelectrochemical pro-

cesses are each covered in a new review by Gomes and Vanmaekelbergh (A138). Electrochemical noise (EN) measurement is a generic term given to methods that monitor fluctuations in current or potential arising from a host of physicochemical processes. Dawson has reviewed the applications of EN in corrosion studies (A139). He discusses the uses of EN analysis of stochastic current pulses for detecting rupture of films on electrodes; discrete events involving dissolution of metal at etch pits, grain boundaries and kink sites; and hydrogen evolution with the interfacial formation and detachment of gas bubbles. Oscillatory behavior of electrochemical systems is discussed in a review by Koper that includes 95 references (A140). A number of chemical examples are given, including dissolution reactions, electrocatalytic oxidation processes, and phenomena observed at semiconductor-electrolyte interfaces. (n) Other Electroanalytical Techniques. There were a number of other reviews that concentrated on a particular electrochemical technique. Chronopotentiometry (A141), luminescence spectroelectrochemistry (A142), transmission spectroelectrochemistry (A143), and interdigitated array electrochemistry (A144) were each covered. Bott presented reviews comparing cyclic voltammetry (CV) to cyclic staircase voltammetry (A145), discussing the use of CV to examine multielectron-transfer reactions (A146), and concentrating on general concepts of interfacial mass transport (A147). Falck discussed the operation of amperometric oxygen electrodes (A148); Duda and Bruntlett provided a general review of amperometric techniques (A149); Denauault (A150) and Hill (A151) wrote articles on microelectrodes. Sonoelectrochemistry was reviewed by Walton and Phull (A152) and then twice again by Compton and cohorts (A153, A154). Electrochemical immunoassay was reviewed by Cousino et al. (A155). Their work in extending the limits of detection of this technique into the zeptomole range is recounted there. Determination of pesticides, herbicides, and other toxic compounds by electroimmunoassay was featured in an article by O’Daly and Henkens (A156). Electrogenerated chemiluminescence was discussed in reviews by Lee (A157), and Knight and Greenway (A158). Two miscellaneous papers with an instrumentation flavor are noted. Novotny and Heyrovsky discuss new types of mercury electrodes with renewable surfaces (A159). Stojanovic et al., present information on computer-based instrumentation for threedimensional voltammetry (A160). Last, one rather short but unusual paper that is neither technique- nor instrumentationoriented is noted. Mogi has written a review of results on electrochemical investigations in high magnetic fields (A161). (o) Materials Electrochemistry. Electrochemical techniques have tremendous utility in the discipline of materials science. One popular research topic in recent years has been the electrochemical investigation of particles with nanometer dimensions. Willig et al. have studied semiconductor particles of nanometer size by a host of techniques, including electrochemistry (A162). Henglein has provided a review focusing on the electronic properties of colloidal nanometer particles from his perspective as one of the pioneers in this area (A163). Polarography and voltammetry of colloidal particles is covered in a paper by Heyrovsky and

Jirkovsky (A164). Specifically, tin dioxide, titanium dioxide and mixed titanium dioxide/ferric oxide colloids are discussed in terms of the particle size dependence of their diffusion behavior and redox potentials. An interesting and informative review of the electrochemistry of fullerenes appeared in 1997 (A165). This article covers C60 as well as the fullerenes C70, C76, C78, C84, and C86. Borondoped diamond thin-film electrodes are discussed by Swain in an engaging A-pages article (A166). Alber et al. summarize work on new electrolyte materials for solid-state amperometric gas sensors (A167). Solid polymer electrolytes, transition metal powders, and inorganic materials prepared by sol-gel processes are each given attention. Applications mentioned include detection of O2, H2, CO, NO2, NH3, and SO2. (p) Environmental Electrochemistry. Electrochemical processes are playing a major role in the search for more benign industrial processes. Trasatti discusses electrocatalysis in this regard (A168). Intermittent water electrolysis; destruction of organic pollutants; ozone, hydrogen peroxide, and chlorine dioxide electrosynthesis; cathodic conversion of CO2; anodic oxidation of SO2; cathodic destruction of NOx; electrochemical replacements for chromates; and the desulfurization of natural gas are discussed. Some of the same topics are covered by Simonsson, with the addition of material on electric vehicles and fuel cells for municipal power generation (A169). An extensive review of the environmental aspects of electrolysis, electrosynthesis, and electrochemical treatment of wastes with 326 references appeared several years ago (A170) and is mentioned here. The electrochemical determination of hydrogen peroxide in environmental studies was the subject of a review by Thomas (A171). Photoelectrochemistry in an environmental context was the subject of three reviews. Lewis discusses aspects of photoelectrochemical research on the semiconductor-liquid interface that have driven recent advances in solar energy conversion (A172). The contributions of photoelectrochemistry to power generation in a broader scope is reviewed by Mraci (A173). Finally, Rajeshwar covers photocatalytic methods for the detection and destruction of pollutants in water and air (A174). (q) Electrochemistry in Neuroscience. The usefulness of electrochemical techniques has been recognized in the field of neuroscience for some time, and several recent reviews cover the types of experiments of interest to researchers in that community. Stamford et al. discuss the use of cyclic voltammetry at fast scan rates for detection of neurotransmitters (A175). Spatial and temporal resolution issues are a major theme of this paper, which focuses on measurements in brain slices. Justice and colleagues summarize results of voltammetric studies probing the kinetics of the wild-type human norepinephrine transporter (A176). The same two authors also have combined forces to publish an A-pages article that neatly summarizes the recent advances in this field (A177). Studies employing carbon fiber electrodes to monitor release of dopamine and noradrenaline by the central and peripheral nervous systems are the subject of a report by Gonon (A178). Angelson and Betz compare amperometry, electrophysiologically based membrane capacitance measurements, and fluorescence methods for following the processes of exocytosis, endocytosis, and vesicle cycling in living cells (A179). Blaha and Phillips Analytical Chemistry, Vol. 70, No. 12, June 15, 1998

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present an extensive review (with 209 references) of various electrochemical approaches for detecting monoamine neurotransmitters during species-typical (i.e., stereotypified) and druginduced behaviors (A180). In vitro and in vivo validation studies are a major focus of this paper. Mas et al. address the uses of voltammetry and microdialysis for neurochemical monitoring of behaving animals during sociosexual interactions (A181). Also reviewed are the advantages of the same two techniques for assessing the effects of endogenous neuromodulators based on monitoring extracellular levels of neurotransmitters and their metabolites in brain tissues (A182). Finally, Neher and Chow compare electrophysiological and electrochemical techniques for studying control mechanisms of secretion in neuroendocrine cells (A183). (r) Bioelectrochemistry. Biological systems often display complex but fascinating electrochemical behavior. Palanti et al. have compiled a review of work on the electrochemistry of DNA published over the last 10 years (A184). They also discuss electroactive hybridization indicators for DNA detection. The subject of electrochemically activated oxidation of poly(nucleic acids) is covered in a review with 77 references by Thorp and colleagues (A185). Their paper also summarizes the electrochemistry of one-electron couples bound to DNA and kinetic results for oxidation reactions as determined by voltammetry. Electrochemical investigations of redox reactions catalyzed by the cytochromes P-450 are catalogued by Estabrook et al. (A186). Interestingly, consistent kinetic results are obtained for these systems when either an electrode or NADPH is used as the source of reducing equivalents. Hong has examined the photoelectrical behavior of bacteriorhodopsin immobilized on optically transparent substrate electrodes (A187). Electrochemical reactions and applications of peroxidase enzymes have been summarized by Ruzgas and colleagues in a review that includes 194 references (A188). Two reviews discussing antibodies that will be of interest to bioelectrochemists are noted. Lu et al. discuss orientation effects in terms of the biological activity of immobilized antibodies (A189). Freitag presents a review of the uses of antibodies in bioanalysis (A190). Her review includes 102 references to contemporary work in this field. The electrochemical study of metalloproteins is an active area, as is evidenced by a review from De Oliveira and Hill (A191). Santucci et al. cover similar ground but also examine the problems inherent in using an interfacial technique to elucidate the details of protein redox reactions (A192). Borsari et al. concentrate on the cytochromes c (A193) and go into depth about the effects of pH, temperature, and solution ionic composition on the redox behavior of this family of metalloproteins. Direct electron transfer between an electrode surface and a redox center in a protein is now recognized as a fairly common occurrence, and examples of such reactions are the subject of a number of reviews. Hill et al. discuss the case of cytochrome c (A194). Ikeda’s paper covers a bacterial membrane-bound flavocytochrome enzyme and a quinocytochrome enzyme (A195). Ghindilis et al. provide a more general review of enzyme-catalyzed direct electron transfer (A196). When direct electron transfer between a native enzyme and an electrode surface is too slow to be observed with reasonable signal-to-noise levels, redox “wiring” of the protein may be feasible. In such cases, attachment of reversible redox couples to the main 528R

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protein facilitates charge transfer to the interface. Heller and his group contributed two papers on this subject recently (A197, A198). Examples discussed include flavoenzymes (sarcosine, glutamate, lactate and glucose oxidases), quinoprotein enzymes (PQQ glucose dehydrogenase), and heme enzymes (peroxidases). An overview of the same area was also published by Pishko (A199). Four unusual reviews in the bioelectrochemical area deserve mention. Senda reviews enzyme reactions in the context of charge transfer at the interface of two immiscible solvents (A200). Somers et al. discuss the coupling of enzymes to an electrode surface for preparative-scale reactions in the food industry (A201). Steckhan and colleagues evaluate the status of electroenzymatic reactions for general synthetic purposes (A202). Finally, Save´ant and associates have published an interesting review of their work on spatially ordered catalytic enzyme assemblies (A203). In this case, antigen-antibody reactions are used for the systematic construction of highly ordered multilayers. Catalytic currents are demonstrated that scale nearly linearly with the number of enzyme monolayers. (s) Biosensors. In the final section on review articles, the area of electrochemical biosensors will be examined. There appear to be a greater number of (largely overlapping) reviews covering biosensors than any other topic in electrochemistry. In what follows, an example review for each focus area in the sensor field will be listed. Since so many of these articles cannot be distinguished from one another, these examples were sometimes chosen arbitrarily. Most readers in search of information on biosensors need look no further than the Clinical Chemistry application review published by Analytical Chemistry during June of odd-numbered years. The most recent version in this series contains a section by Wang on electroanalysis and biosensors (A204). Enzyme electrodes, immunosensors, DNA biosensors, optical sensors, ion-selective electrodes, voltammetric sensors, and amperometric sensors are each covered there. More specialized reviews are available on a number of topics. In the environmental biosensor area, reviews have recently appeared discussing determination of pesticides (A205), water monitoring (A206), bioprocess monitoring (A207), and remote sensing (A208). A critical overview of the area was also published in the ACS journal Environmental Science and Technology (A209). There are several reviews available on immunosensor technology. The most complete treatment seems to be a paper by Morgan et al. published in the journal Clinical Chemistry (A210). Electrochemical sensors based on nucleic acid hybridization are covered by Yang et al. (A211). The vast majority of electrochemical biosensor papers involve the use of oxidoreductase enzymes (oxidases, dehydrogenases). These enzymes can be incorporated into a sensor in a number of ways including immobilization in a polymer film (A212), incorporation into an electronically conducting polymer (A213), inclusion in a carbon paste or ink matrix (A214), encapsulation by solgel reactions (A215), or through intimate contact with an electrode capable of direct electron transfer to the enzyme (A216). In some cases, entire cells, organelles, or catalytically active cell fragments may be immobilized instead of a purified enzyme (A217).

Reviews of specific biosensor applications are also very common. A few examples include summaries of biosensor work in organic chemistry for enantiomeric analysis (A218), drug metabolism analysis (A219), the drug discovery process (A220), biomedical applications (A221), diabetes management (A222), microdialysis and ultrafiltration (A223), food analysis (A224), and kinetic studies in organic solvents (A225). MASS TRANSPORT Mass transport is a very important process which is an important part of virtually all heterogeneous reactions, including electrochemical reactions, in which the reactants are not bound to the heterogeneous reaction site. During the period of this review, more than 900 papers appeared which might logically be classified as having relevance to this topic in the context of electrochemical reactions. Although one might naively assume that virtually all of the interesting mass transport problems have already been solved, the continuing progress of electrochemical research has continually unfolded new problems where new theoretical treatments must be developed. In many cases, the new problems bring with them increasingly greater mathematical challenges. As electrochemical experiments are increasingly carried out in very small spatial regions with increasingly smaller electrode dimensions, multiple modes of mass transport must increasingly be considered simultaneously, when heretofore it was often feasible to set up an experiment so that only one mode of mass transport, such as diffusion, was dominant. One trend that is becoming increasingly prevalent is the use of more sophisticated numerical modeling techniques to deal with these more complex systems. While analytical methods continue to find use (though fewer in number than numerical methods), finite difference techniques tend to dominate, with a scattering of other methods such as finite element (of which orthogonal collocation is a special case), boundary integral, and network analysis. A dramatic increase in the use of implicit finite difference simulation methods is particularly noted. These and still more sophisticated techniques are needed to handle problems such as mass transport problems in two or three spatial dimensions, and perhaps a time dimension as well, or stiff problems such as encountered when the spatial dimension on which a coupled chemical process is occurring is much smaller than the spatial dimension of mass-transfer depletion. Such problems also frequently benefit greatly from the use of expanding space grids, which can dramatically reduce the number of calculations required. The discussion here will focus on some of the generally applicable developments in mass transport simulations and theory reported in the literature. Particularly important subtopics include microelectrodes; hydrodynamic systems including rotating, walljet, and channel flow electrodes; and interacting electrodes. The latter include generator/collector electrode assemblies of two or more electrode pairs, arrays of electrodes, and scanning electrochemical microscopy electrodes, which form a special case of collector/generator assemblies with spatial resolution. (a) General Mass Transport Theory. A number of papers have appeared that have as a primary focus calculation methods in mass transport, and their uses and limitations in the treatment of a wide variety of electrochemical problems. In addition to these

papers, the interested reader may also consult the Electrochemical Science and Technology Information Resource Web site, which maintains information on a number of shareware simulation software resources (B1), the Compton Group Web site, which offers guest access to simulation methods for calculation of steadystate voltammetry for a variety of electrode geometries and a whole range of EC, ECE, DISP, and EC′ reaction mechanisms (B2), and several commercial sites (e.g., Bioanalytical Systems, which distributes DigiSim, a versatile implicit finite difference simulator for cyclic voltammetry developed by Feldberg, Rudolph and collaboratorsssee Table 3 for URL) for information on free and commercially available software. Fang and Chen discussed a strategy for improving the accuracy of finite difference simulations based on adding more finely spaced time points before the first point at which results are desired (B3). The Compton group has contributed a number of papers on electrochemical simulations, including a review of the strongly implicit finite difference method for modeling transient electrochemical processes for both micro- and macroelectrodes, with comparison of its performance to alternative methods (B4), and a comparison of finite difference algorithms for simulating microband electrode problems in the presence or absence of convective flow (B5). They skeptically addressed the question whether a one-dimensional approximation is an appropriate solution for a multidimensional problem, e.g., approximating a microdisk electrode as either a planar or a hemispherical electrode, as is frequently done (e.g., in the commercially available simulator DigiSim). They reached the logical conclusion that the strategy can be risky for transient experiments, even though it can work well in limiting cases (B6) and instead suggested a general two-dimensional strategy based on use of a single sparse matrix formulation for both transient and steady-state experiments with provision for quasireversible electron transfer and several possible coupled chemical step mechanisms at both microdisk and channel band electrodes (B7). Conformal mapping significantly improves the efficiency of the approach (B8). They also described an efficient automated simulator of a variety of steadystate reaction mechanisms at a variety of electrode geometries (B9), which is accessible for use by other researchers via a World Wide Web site (B2). Finally, they also extended the approach to simulate double electrodes in a flow channel using a multigrid method (B10). Gavaghan also addressed the question of accuracy in 2-D simulations, pointing out that a fundamental stumbling block arises from the discontinuities that occur at electrode edges (the infinite current density problem) when more than one spatial dimension must be considered (B11). Bieniasz et al. considered the numerical stability of several finite difference algorithms. They compared the stability of the classical explicit, the partially implicit Crank-Nicolson, and fully implicit methods, noting the sometimes ignored fact that the Crank-Nicolson method is only conditionally stable because of its explicit components, whereas the fully implicit method is unconditionally stable. They also showed that the use of multipoint gradients to improve stability offers little advantage over conventional two-point gradients (B12). They also evaluated the Saul′yev finite difference method and concluded that the method is not as unconditionally stable as advertised (B13). Feldberg et al. also discussed a stability criterion for accurate Analytical Chemistry, Vol. 70, No. 12, June 15, 1998

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simulation of electrochemical diffusion/kinetic problems at the rotating disk electrode, which they have incorporated into their general simulator for cyclic voltammetry (on which DigiSim is based). They also discussed implications for modeling systems involving both diffusion and migration (B14). Bott presented concentration-distance profiles simulated by DigiSim under a variety of conditions (B15). A couple of papers appeared using the commercially available electrical network analysis program PSPICE to solve electrochemical problems, including simulation of cyclic voltammetry for Butler-Volmer electron-transfer kinetics with coupled chemical reactions in a four-member scheme of squares (B16) and simulation of chronoamperometry for first- and second-order catalytic mechanisms (B17). Jin et al. introduced a finite analytical numerical method for simulation of electrochemical problems, which differs from finite difference and finite element simulations in being based on solution of an algebraic equation obtained from local analytical solutions. The method was applied to microdisk and microband electrodes for several combinations of homogeneous and heterogeneous kinetic conditions (B18). Stevens et al. discussed the use of finite element simulations in electrochemistry (B19). Gosser reviewed the simulation of electrochemical mechanisms in cyclic voltammetry (B20). Speiser made a major review of numerical simulation methods in electroanalytical applications, with an emphasis on recent developments (B21). Geshev used the boundary integral equation method to obtain a numerical solution via Green’s function for convective diffusion (B22). Cope and Tallman presented an integral equation method for transient currents based on integration in the Laplace plane and numerical inverse transformation to obtain the time-dependent current (B23). Engblom et al. also used this method to model the transient diffusion current at a tubular band electrode (B24). Cope also discussed a series expansion to obtain a numeric solution for the description of quasireversible cyclic voltammetric response (B25). (b) Spatial Probes. Several workers considered spatial distributions of concentration gradients adjacent to electrodes. Unwin and co-workers have presented theory for several aspects of SECM experiments, including treatment of the double potential step chronoamperometric mode for measuring local reactivity at liquid-solid, liquid-liquid, and liquid-gas interfaces (B26); use of the substrate generator/scanning tip collection mode to measure the diffusion coefficient ratio of a redox couple (B27); induction of dissolution of a substrate by the scanning electrochemical probe, with application to dissolution of silver chloride in absence of supporting electrolyte (B28); and application of SECM to study the kinetics and differentiate between ECE and DISP1 mechanisms (B29). Klusman and Schultze discussed both the theory and experimental verification for generation and measurement of pH gradients adjacent to a microelectrode, detected by a spatially scanned pHmicro electrode (pH microscopy) (B30). (c) Hydrodynamic Experiments. A number of authors addressed simulation of reactions under hydrodynamic voltammetric conditions. Stevens and Fisher discussed the use of finite element simulations for hydrodynamic voltammetry at macro- and microelectrodes including the microband (oriented perpendicular 530R

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to flow) and the microstrip (oriented parallel to flow) in a thinlayer flow channel. They argued that the approach had several potential advantages in efficiency over finite difference simulations for more complex electrode geometries (B31). Aixill et al. treated the hydrodynamic microstrip in a flow channel for both transient and steady-state experiments, considering the effects of multidimensional diffusion (B32). Ferrigno et al. used finite element calculations to consider the effect on amperometric response of recessed or protruding microband electrodes relative to the wall of flow channels (B33) and recessed or protruding microdisk electrodes (B34). Compton and co-workers simulated the effect of comproportionation and dimerization of a reduction product generated at a channel electrode on the voltammetric response and satisfactorily applied the approach to evaluation of the comproportionation (B35) and dimerization of the methyl viologen radical cation (B36). They also discussed the use of strongly implicit and multigrid methods for simulation of voltammograms involving electron-transfer reactions varying between reversible and irreversible at electrodes in flow channels (B37) and described an analytical solution for ECE and DISP1 mechanisms in a flow channel (B38). They also modeled and experimentally investigated a very interesting self-inhibiting disproportionation reaction mechanism, involving photochemical excitation of photoreduction, complicated by a finite rate of comproportionation as the reverse of the disproportionation reaction and quenching of the excited state which leads to reaction at a channel flow electrode (B39). (d) Microelectrode geometries. A number of theoretical treatments of microelectrodes of various geometries appeared in the literature, including an application of the finite analytical method to simulation of electron transfer at a microring electrode (B40) and prediction of the steady-state current at a ringlike electrode (including the microring as one limiting case) for a not completely diffusion-controlled steady-state current limited by electron transfer as well as diffusion (B41). In a similar vein, Antonello and Maran published a provocative paper on the effects of the transition of a relatively slow electron-transfer mechanism accompanied by bond cleavage from a concerted to a stepwise mechanism as a function of applied potential. The results are qualitatively interpretable in terms of a nonlinear potential dependence of the electron-transfer rate coefficient R (B42). These observations have some relevance to the quest to confirm the Marcus theory regarding the potential dependence of the transfer coefficient. Compton and co-workers treated chronoamperometric current transients for the ECE mechanism at hemicylinder and band microelectrodes (B43). Several treatments of voltammetry at a hemispherical microelectrode appeared, including a catalytic process (B44), quasireversible electron transfer (B45), and both an analytical treatment of chronoamperometric response (B46) and a finite analytical simulation of cyclic voltammetric response (B47) at an oblate hemispheroid electrode. Oldham’s group has treated a number of interesting cases. Alfred and Oldham treated a number of cases ranging from various sections of a hemispherical electrode such as a mercury drop grown on a microdisk, from initial formation of a shallow dome to formation of an entire sphere emerging from an insulating plane (B48).

Oldham evaluated the effect of a number of electrode geometries and shapes on short-time, diffusion-controlled response to a potential step perturbation and evaluated the effects of features such as curvature, edges, and vertexes on response (B49) and the effect of a right-angled electrode edge, when the electrode abuts either an adjacent electrode or an insulating plane (B50). Sokirko and Oldham treated potential step chronoamperometric response at a conical electrode, with the intriguing result that voltammetric response should be independent of the diffusion coefficient for the specific case of a semiapical angle of 54.74°. The results also provide insight on the effect of vertexes (another site of discontinuity) on voltammetric behavior, particularly at short times (B51). Jin et al. developed an analytical approach to describe fast cyclic voltammetric response at microdisk electrodes and were able to extract experimental electron-transfer kinetic parameters (B52). Fisher et al. used fully implicit finite difference simulations to model potential step chronoamperometry and cyclic voltammetry at microdisk electrodes in a flow channel, including the effects of axial diffusion (B53). Cassidy et al. simulated the transient potential response at a rotating disk ion-selective membrane electrode in response to a potential step. They asserted that transient changes in double-layer composition led to the observation of mass-transfer effects on the membrane potential not predicted by a theory that ignored this effect (B54). Jin and Chen developed an analytical expression for the electromigration rate dependence of an end-column amperometric detector for capillary zone electrophoresis (B55). (e) Stripping Voltammetry. Several groups treated various theoretical aspects of stripping voltammetry. Ball and Compton simulated and experimentally evaluated stripping at uniformly accessible mercury thin-film electrodes under hydrodynamic conditions using the time-dependent backward implicit method (B56). Schiewe et al. also simulated and experimentally evaluated stripping at mercury thin-film electrodes under stationary conditions (B57). Kamenev et al. simulated and measured voltammetric stripping response of thallium and cadmium in a mixture (B58). Garai et al. presented a theory of differential and derivative potentiometric stripping voltammetry (B59). Honeychurch and Ridd treated the interfering effect of a nonadsorbing electroactive species on the transition time expected in derivative adsorptive chronopotentiometric stripping analysis (B60). Bi and Yu treated cyclic reciprocal derivative chronopotentiometry (B61). Pizeta and Branica simulated stripping voltammetric response for determination of the total complexation capacity of a metal ion in the presence of up to three complexing ligands (B62). van den Hoop et al. addressed the stripping voltammetry of heavy metal/ polyelectrolyte complexes (B63). Some papers that have potential relevance to stripping voltammetry include the treatment of double-pulse chronoamperometry at spherical electrodes for long pulse durations, using higher-order spherical corrections, for species that can form amalgams (B64); a general analytical solution for triple potential step chronoamperometry at a static mercury drop electrode with and without amalgam formation (B65); and a model for voltammetry of metal ions in the presence of mixtures of macromolecular and simple ligands and calculation of cyclic voltammetric response for reductive formation of catalyst-substrate adducts on electrode

surfaces (B66). Anson’s group treated the cyclic voltammetric response for reductive formation of monolayer catalyst-substrate adducts on the electrode surface (B67). (f) Treatment of Various Electrochemical Techniques. Staircase voltammetry has been treated for a thin-layer cell (B68), and both staircase and several modes of differential staircase voltammetry have been treated for a microelectrode (B69). A general solution for the double-pulse EC′ catalytic mechanism was presented which is suitable for all modes of differential pulse voltammetry (B70). Speiser used orthogonal collocation to simulate controlled-current bulk electrolysis (B71). Moharram described a new data treatment method for extraction of quasireversible electron-transfer kinetic parameters using convolution data analysis (B72). (g) Membrane-Based Sensors. A number of important applications are based on processes coupled through membranes, including the important class of enzyme biosensors as well as specialized sensors such as the oxygen electrode. Many other practical systems involve membranes or systems that mimic membranes. Treatments have appeared on a glucose oxidaseimmobilized polymer sensor for glucose (B73), a diffusion-limited glucose amperometric enzyme biosensor (B74), an amperometric bienzyme sensor (B75), an implicit finite difference simulation of a multilayer enzyme sensor under steady-state and transient conditions (B76), the simulation of the diffusion of oxygen across a biofilm membrane under conditions of steady-state hydrodynamics at a rotating disk electrode (B77), a treatment of a membranecovered disk microelectrode under conditions of steady-state radial diffusion at the microelectrode (B78), and the modeling of the non-Cottrellian switch-on response of a Clark-type membranecovered oxygen microelectrode electrode (B79). Other interesting cases include the treatment of a thin-layer redox system with a diffusion coefficient that varies with distance from the electrode (B80), which may be particularly relevant to cases such as polymer films and membranes in which the polymer swells and shrinks according to solvent and ion flux, and the simulation of the temporal response of a tungsten oxide-based electrochromic “smart” window to a current pulse (B81). (h) Microelectrode Arrays. A number of treatments of microelectrode arrays have appeared. Morf treated the transient chronoamperometric response of microelectrode arrays of disk or hemispherical microelectrodes of varying packing density to changes in applied potential, flow rate, or concentration (B82) and the steady-state response for multiple microelectrode arrays of varying microelectrode geometry and packing density (B83). Cohen and Radke treated ionic surface diffusion using an electrostatic patchy charge model (B84). Jin et al. used the finite analytical method to treat both transient and steady-state responses of coplanar and elevated interdigitated band microelectrode arrays (B85). Compton and co-workers modeled the timedependent amperometric response of the downstream electrode of a dual generator/collector electrode pair in a thin-layer flow channel to a potential step at the upstream electrode (B86). (i) Electrochemical Impedance. Compton and co-workers modeled and experimentally measured the impedance spectrometric response of a pair of electrodes in a flow channel downstream of an insulating solid to investigate the hydrolytic dissolution mechanism of the solid in a solvent of low ionic Analytical Chemistry, Vol. 70, No. 12, June 15, 1998

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strength (B87). Chen et al. modeled the hydrogen insertion reaction under conditions of restricted diffusion (B88). Grafov and Damaskin treated the case for a mixed electrolyte solution (B89), while Martinusz et al. treated a conductive polymer film using computer simulations and complex nonlinear least squares for data fitting (B90). Blankenbourg et al. treated the theory of impedance and demodulation voltammetry for electrode reactions involving both electron-transfer kinetics and reactant adsorption and applied the results to the reduction of Tl(I) at a mercury electrode (B91). Prieto et al. modeled the impedance voltammetry of a consecutive ECE mechanism with two diffusing intermediates and applied the model successfully to the reduction of nitromethane (B92). Koper presented a general model for treatment of the impedance spectrum of an electrochemical cell under potentiostatic conditions for prediction of the frequency response and stability of the cell under various possible experimental conditions including galvanostatic (B93). (j) Adsorption. Calvente et al. reported the orthogonal collocation numerical modeling of the chronoamperometric transient response for adsorption/desorption of adsorbates obeying a nonlinear Frumkin isotherm (B94). Meunier-Prest and Laviron presented the theory for the cyclic voltammetric response for an EE mechanism with two 1-electron transfers coupled with surface reactions (B95). (k) Mixed Mass Transport. A number of reports focused on examples of these increasingly important cases. Georgiadou reported a finite difference treatment of coupled diffusion, migration, and laminar convection for multi-ion electrolytes at dual parallel opposed electrodes and for a backward-facing step electrode upstream of a detector electrode in a flow channel (B96). Bortels et al. applied the multidimensional upwinding technique for steady-state response of parallel electrodes in a laminar flow channel with coupled diffusion, migration, and laminar convection (B97). Oldham and co-workers theoretically treated (B98) and experimentally measured (B99) the effect of ion pairing on the steady-state voltammetric limiting currents in solutions of high resistivity governed by mixed diffusion and migration for both charged and uncharged species in toluene. Oldham also treated the effect of a range of diffusion coefficient values on the steadystate limiting voltammetric response for mixed diffusion and migration in the presence of homogeneous equilibria (B100). Jaworski et al. experimentally tested the theory for coupled diffusion and migration coupled with homogeneous equilibria, with application to the voltammetry of weak acids (B101). Stojek’s group simulated the transient amperometric response for undiluted liquids with coupled diffusion and migration and concentration-dependent diffusion coefficients (B102). They also used the Crank-Nicolson implicit finite difference method to simulate numerically the effect of electron-transfer kinetics on the transient chronoamperometric response of uncharged species under conditions of coupled diffusion and migration (B103) and the effect of carrying out the experiment in the presence of deficient concentrations of supporting electrolyte (B104). Strutwolf and Schoeller simulated the linear sweep and cyclic voltammetric response at a rotating disk electrode (B105) for the case of coupled diffusion and convection. (l) Ohmic Distortion. The perennial problem of ohmic distortion because of uncompensated iR drop either due to 532R

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solution resistance or due to electrode resistance was also treated by multiple groups. Garcia-Jareno et al. treated the contribution of a resistive electrode material such as the semiconductor indium tin oxide on the distortion of cyclic voltammetric response of the Prussian blue system (B106). Coles et al. modeled the effect of ohmic distortion on mass transport and voltammetric response of thin-layer flow channel electrolytic cells, by iteratively coupling the electrical network finite element program SPICE for determination of solution resistance with the backward implicit finite difference method to calculate the current distribution across the electrode and channel. Theoretically predicted response agreed well with experiment (B107). Yamada et al. used an integral equation approach to derive an approximate theoretical treatment of the response time of a circular thin layer to a potential step signal, including the effects of both ohmic distortion and doublelayer charging (B108). (m) Nucleation and Growth. These phenomena can be dominant processes in electrochemical reactions that involve the deposition of a solid reaction product. They are generally neglected in the standard electrochemical course work to which students in the United States are usually exposed, although they are treated some in scattered sites. The electrochemical response can behave quite differently than expected if these phenomena are not taken into account. Arvia’s group has applied dynamic scaling theory to describe interface evolution in the industrially important process of copper electrodeposition in the presence of organic additives (B109) and in the general case of development of roughness of deposits at solid electrodes (B110). Tadano and Aogaki applied nonequilibrium fluctuation theory to derive nucleation current equations (B111) and to predict nucleation current for silver nucleation on platinum (B112). Nagy et al. applied threedimensional random walk simulations to model diffusion-controlled processes at a hemisphere electrode, a disk electrode, and a growing hemisphere electrode (B113) and to model the electrodeposition of random arrays of growing hemispheres. They were able to derive a simple analytical expression which adequately described the experimentally observed behavior (B114). Huang and Hibbert simulated the effect of applied potential on probability, morphology, and fractal dimension during fast fractal growth of an electrodeposit for conditions of coupled diffusion, migration, and convection (B115). Harrington used Monte Carlo methods to simulate the effects of migration and surface diffusion on the growth of thin platinum oxide films. He concluded that the limiting step was the slow migration of a surface Pt(0) atom to become a Pt(II) ion, followed by rapid surface diffusion. He was able to predict essential features of cyclic voltammograms on the first and subsequent oxidative sweeps (B116). (n) Special Cases. Dezhkunov analyzed the effect of ultrasonic cavitation on electrochemical electron-transfer kinetics using a Marcus formalism (B117). Yamaguchi et al. presented a theory of mass transport properties for the ultimate interface, a single atomic junction (B118). Green et al. considered the effect of dielectrophoretic motion of polarizable particles in a nonuniform ac field (B119). Although electrochemists typically attempt to work with clean, nonparticulate systems, systems such as this are actually of considerable significance in governing redox processes in the real world, for example, in environmental redox processes. Saltykov and Kornienko applied fractal theory to describe the

Table 4. Frequency of Usage of Electrochemical Terms in Electrochemical Papers term voltammetry polarography alternating current cyclic plus linear sweep pulse methodsstotal (other than square wave) differential pulse other than differential (e. g., normal) square wave staircase amperometry chronoamperometry chronopotentiometry coulometry hydrodynamic methodsstotal, including flow, rotation, etc.) flow methodssincluding chromatography flow methods other than chromatography chromatography “hydrodynamic” rotating electrode rotating disksnot ring-disk rotating ring-disk other rotating electrode stripping methodsstotal anodic stripping adsorptive cathodic potentiometric electrode array sensor biosensor

% of papers 30 2 0.2 17 8 5 3 3 0.3 8 3 1 3 16 12 8 4 2 4 2 1 1 11 4 4 2 2 2 9 4

behavior of porous electrodes (B120). Finally, Engelhardt et al. treated the significance of thermal diffusion in high-temperature electrochemical systems (B121). ANALYTICAL VOLTAMMETRY The definition of “voltammetry” for the purposes of this review is broadened slightly from its normal definition involving measurement of voltammograms or displays of some function of current vs some function of potential to include methods that involve the dynamic reaction of reactant or generation of product. This is necessitated by the direction that the general field of electroanalytical chemistry is currently taking. Thus, the definition is expanded to include various amperometric detection methods in flow streams, sensors, or biosensors, for example. In this context, it is instructive to examine the current practice of analytical electrochemical measurements, as obtained by a computerized search of words used in titles or abstracts of papers using electrochemical methodology. The following breakdown (Table 4) is based on a total of nearly 4400 abstracts involving dynamic electrochemical techniques (excluding purely potentiometric methods) that were collected during the preparation of this paper, which were in turn culled from nearly three times that many citations. Keywords are listed in terms of the percent of citations that used those keywords or kernel portions thereof. Percentages are rounded off to the nearest percentage point; some subtotals do not add up to the corresponding totals as a result. As usual, a huge number of papers that fit into this category were published during the review period. More than 1200 papers in the computerized bibliography search for this review were classified as related to analytical voltammetry. Given the vast range of application papers that exist in the literature, an eclectic

selection of papers is cited here, based either on novelty of the application or on significant features reported in the papers. Many interesting papers were excluded due to the lack of space. For the most part, an attempt is made to avoid covering the same limited number of analytes that have continually dominated the electrochemical literature since time immemorial. Because of the increasing importance of flow methodologies coupled to electrochemistry, with their advantages for high throughput and on-line analysis, many of the examples cited are drawn from the literature of flow-coupled electrochemistry. However, these cover as wide a swath of electroanalytical techniques as can be covered by static methodologies and, therefore, provide a broad perspective on the state of the field in general. Moreover, in the opinion of this reviewer, flow-coupled methodologies as well as some in situ sensors and biosensors represent the best hope for electrochemistry to become a widely used tool of the analytical chemist rather than a niche tool used only by specialists. It is very clear from looking at the literature as a whole that considerable effort is continually expended to measure the same analytes over and over again, sometimes with relatively little variation in the approach. Sometimes apparently new developments are tracing the path of work done so long ago that no one remembers it anymore. For example, several papers described the use of graphite pencil leads for preconcentration and stripping of heavy metals or organic species (C1-C3). Pencil leads have not been used extensively recently for analytical purposes, and so their application appears novel. One of these papers described graphite pencil leads as “new” electrodes for abrasive stripping voltammetry (C3), which they undoubtedly are in the context of the work reported. However, how many people remember that the graphite pencil lead was probably the very first carbon electrode used for electrochemical trace analysis, and in fact by stripping voltammetry, fifty years ago, or that the detection limits achieved then have rarely been surpassed in the decades since? L. B. (Buck) Rogers used a pencil lead to demonstrate stripping voltammetry of trace metals in the late 1940s at Oak Ridge National Laboratory. Graphite was chosen on the advice of atomic spectroscopists as a material with very low contamination with trace metals which interfered with determinations at very low concentrations. Another concern that all researchers and methods developers should continually examine is whether they are developing a new method because it has potential to yield significant improvements in analytical capabilities compared with existing methods or whether they are developing the method simply “because it is there” and they happen to have the necessary expertise and equipment to do it. This can lead in some cases to solutions for nonexistent problems or solutions that are sometimes considerably more complex than already existing approaches with little or no analytical reward for the added complexity. A number of examples of this approach were encountered during this review period. We would all benefit if careful self-examination and thought went into the planning of experiments at the beginning rather than at the end. The terms in the table are generally not exclusive, and many papers incorporate various combinations of terms. It is apparent that the term voltammetry is still dominant among all the terms in the table, encompassing 30% of all the entries, but that this is Analytical Chemistry, Vol. 70, No. 12, June 15, 1998

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fragmented among numerous subtypes, of which cyclic and linear sweep methods account for approximately half of the cited uses of voltammetry, and the pulse methods account for another quarter of voltammetric citations. Of the pulse methods, differential pulse is still the most popular, although square wave voltammetry is becoming competitive and may in time be expected to have a comparable level of usage. Stripping methods are still very popular for trace analysis, because of the preconcentration and cleanup possibilities afforded by predeposition of analyte on the electrode surface. There are roughly one-third as many stripping citations as voltammetric citations. Anodic and adsorptive stripping techniques are roughly equally commonly used, followed by cathodic stripping and potentiometric stripping, which is a special case that can be applied for all three techniques. Interestingly, the hydrodynamic methods, encompassing flow methods including chromatography and rotating electrode methods among others, already have a distribution equal to cyclic and linear sweep methods and slightly greater than stripping methods. This trend is expected to continue indefinitely, because of the many advantages of flow technology, which can in many cases greatly enhance electrochemical capabilities, particularly when separations are incorporated into the process for greater selectivity. Note that, in many cases, the flow methods are also applied to stripping methodologies, since flow methods again are very useful in automating and improving the productivity of stripping methods. Amperometric methods have a distribution comparable to the pulse methods and nearly competitive with stripping methods. This is undoubtedly in large part due to the dominance of amperometric detection in flow methods. Note that amperometry and chronoamperometry are essentially orthogonal to each other. Of particular interest is the continuing surge in applications of electrode arrays. The array nomenclature is somewhat complicated by multiple uses of the term (e.g., a microelectrode array consisting of a series of small electrodes in close proximity to one another has quite different practical connotations than an array of coulometric detector electrodes for liquid chromatography, which are a series of flow-through porous electrodes placed in sequence). However, the same basic ideas underlie the applications of the arrays of whatever configuration, namely, exploiting the advantages of using multiple electrodes either to do parallel and independent sensing or to interact with one another in a generator/collector mode for enhanced selectivity or sensitivity/improved detection limit. Nearly 100 papers on arrays appeared during the review period, a significant fraction of which were applied for quantitative measurements of analytes, as opposed to simply characterization of the electrodes or use for study of a reaction mechanism. In this respect, array electrodes found a significantly wider use for analytical measurements than the more mature rotating ring-disk methodology. This trend can also be expected to continue. General Reviews. A number of articles have appeared reviewing various aspects of analytical voltammetry. Niwa and co-workers reviewed the use of interdigitated microelectrode arrays as sensors for a variety of applications from stationary solutions to flow systems (C4). Kauffmann et al. reviewed the potential of electroanalytical techniques for pharmaceutical analy534R

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sis, covering a broad spectrum of electrochemical techniques (C5). Trojanowicz and Hitchman reviewed the use of electrochemical biosensors for determination of pesticide residues in the environment and in food samples (C6). Qu exhaustively reviewed recent developments in the determination of precious metals, including electrochemical methods among many others (C7). Walcarius extensively reviewed the use of zeolite-modified electrodes for electroanalytical applications using a wide variety of electrochemical methods (C8). Ewing and co-workers reviewed the use of voltammetric microelectrode methods and related techniques for analysis of constituents of single biological cells (C9, C10). Several reviews of electrochemical detection in flow systems have appeared. Budnikov reviewed the use of voltammetric detection in flow injection analysis (C11). Both Kissinger (C12) and Weber and co-workers (C13) reviewed electrochemical detection in bioanalysis, for both liquid chromatographic and capillary electrophoretic applications. Davies reviewed carbohydrate chromatography in general, with particular emphasis on electrochemical detection as well as fluorescence detection after derivatization for the best detection limits (C14). Several groups also extensively reviewed the theory and practice of coulometric detectors in liquid chromatography (C15-C17). The latter two articles, which describe both single coulometric detectors and arrays of coulometric detectors in liquid chromatography for a wide range of applications, appeared in a volume that also contains a large number of additional papers on the subject, including another paper on liquid chromatographic food analysis using arrays of coulometric detectors (C18). LaCourse also exhaustively reviewed the applications of pulsed electrochemical detection in liquid chromatography (A9). Cyclic Voltammetry. Largeaud et al. demonstrated the ability to distinguish between R- and β-D-glucose anomers through selective oxidation of the β-anomer at platinum electrodes and characterized the oxidation products (C20). Yu et al. reported the determination of ethanol in wine by oxidation using potassium ferrocyanide as an internal standard, with detection limits of 0.023% (v/v) ethanol for cyclic voltammetry, vs 0.012% for square wave voltammetry (C21). Vogt et al. described the detection of various gases, including O2, N2, CO2, CO, CH4, and NO using cyclic voltammetry at a heated cermet multilayer sensor, with use of a neural network to train the sensor to recognize the signatures of the various gases (C22). Paras and Kennedy used cyclic voltammetry at a carbon fiber electrode with a scan rate of 800 V/s to detect and distinguish from other peptides the peptide R-MSH in a single pituitary melanocyte cell and to monitor exocytosis events from single melanocyte cells, taking advantage of the adsorption of the peptide at the electrode surface to enhance selectivity and sensitivity (C23). Brajter-Toth and co-workers discussed the advantages of using fast-scan cyclic voltammetry at scan rates in excess of 1000 V/s for improved detection limits and discrimination against interferences for species such as dopamine and uric acid, in the presence of interferences such as ascorbic acid (C24). It should be noted that high scan rates can lead to trouble for analytes that do not adsorb on the electrode but are advantageous for adsorbed species. Michael and co-workers applied supercritical fluid chromatography with cyclic voltammetric detection for the determination of

phenols and polynuclear aromatic hydrocarbons with low-nanogram detection limits (C25). Parker and Seefeldt discussed the use of cyclic voltammetry in a mediated thin-layer voltammetric cell for determination of reduction potentials and kinetics of redox proteins including cytochrome c, ferredoxin, and the iron protein of the redox enzyme nitrogenase (C26). Takamura et al. studied the use of cyclic voltammetry coupled with flow injection analysis to determine serum lipase after incubation with fatty acids which react with 2-methyl-1,4-naphthoquinone (C27). Cullison and Kuhr discussed the use of cyclic voltammetry with second-harmonic lock-in detection as a flow detector, with impressive detection limits an order of magnitude lower than for dc amperometry (C28). These results are especially significant, because heretofore it was accepted common wisdom that voltammetric or pulsed detectors could at best approach the detection limits of constant potential amperometric detectors except in special cases where electrode fouling or other adverse circumstances precluded successful detection with constant-potential amperometric detectors. This approach may open up new opportunities for improved and more versatile detectors. Tess and Cox reported an innovative solid-state amperometric sensor for carbon monoxide, based on a porous silica film cast by sol-gel techniques over an interdigitated electrode array. The response was essentially independent of humidity over a wide range and gave good sensitivities (C29). Sinusoidal (Alternating Current) Voltammetry. Kuhr and co-workers have continued their work with sinusoidal wave forms for analytical detection. Their large-amplitude wave form harks back to the old days of oscillographic polarography. They exploit the difference in frequency content and phase between background and Faradaic current to extract the analytical information. They reported detection of carbohydrates at copper electrodes with detection limits of 8 nM for glucose under flow injection conditions, using digital postprocessing of the signal to get the equivalent of lock-in amplifier detection (C30). They also investigated the detection of both purine-and pyrimidine-based nucleotides at copper electrodes in flow streams, with detection limits in the ∼70-200 nM range, more than 2 orders of magnitude better than achievable with UV absorption detection in flow systems such as chromatography or electrophoresis (C31). These methods and the previously mentioned development for lock-in detection for cyclic voltammetry are closely related. It will be interesting to see whether either the sinusoidal approach or the triangular wave scan approach will win out. Pulse Voltammetry. (a) Differential Pulse (DP) Voltammetry. The majority of applications reported here are covered under stripping voltammetry. Vaz et al. reported use of differential pulse voltammetry (polarography) to determine adsorption isotherms of atrazine herbicide on tropical soils of different composition (C32). (b) Square Wave (SW) Voltammetry. The majority of the square wave papers reported here are listed under stripping techniques or other headings. Berzas Nevado et al. used SWV to determine the pharmaceuticals sulfamethoxypyridazine and trimethoprim simultaneously in mixtures, either directly or via SW adsorptive stripping voltammetry. They applied the partial least-squares chemometric method to facilitate the resolution of the overlapping peaks (C33). Along related lines, Fang and Chen

reported an adaptive wavelet filter that may be useful for smoothing or resolving a wide variety of peak-shaped voltammetric wave forms as well as flow injection or chromatographic peaks (C34). (c) Pulsed Amperometric Detection (PAD). Hoekstra and Johnson compared PAD wave forms with those for other techniques such as integrated voltammetric detection and integrated square wave detection for the detection of biogenic amines in complex mixtures separated by liquid chromatography. The latter techniques have detection limits about 5 and 8 times lower than for PAD, which exhibited a detection limit of 300 pg for 1,3diaminopropane (C35). Tallman and co-workers discussed the detection of glucose by PAD at a rotating gold composite electrode composed of gold powder and Kel-F. They reported a 3-fold improvement of signal/noise ratio due to the microelectrode arraylike structure of the composite electrode relative to a solid gold electrode (C36). Weitzhandler et al. described strategies for eliminating amino acid and peptide interferences in anionexchange chromatography with PAD of glycoprotein monosaccharides (C37). (d) Pulsed Electrochemical Detection (PED). Roberts and Johnson discussed optimization of pulse wave form parameters for PED at a gold microelectrode for separation of alditols and carbohydrates by capillary electrophoresis (C38) and applied PED at gold electrodes for detection of monoamines and diamines separated by liquid chromatography (C39). Doscotch et al. exploited an otherwise undesirable problem for analytical purposes by observing that adsorbed species can attenuate the cathodic current for reduction of dissolved oxygen. This observation was used to detect a variety of species such as amines, halides, and sulfur compounds indirectly in a flow stream, both for flow injection and for chromatographic experiments, with detection limits comparable to normal PED techniques (C40). (e) Staircase Voltammetry (SCV). Fung and Mo determined ethanol in beer using flow injection dual-pulse SCV. They found a detection limit of 0.6 mM, with a throughput of 60 samples/h, and no need for deaeration (C41). Yu et al. found a slightly higher detection limit of ∼2 mM using a similar flow injection SWV approach for wine (C21). (f) Miscellaneous Pulsed Voltammetry. Chen et al. discussed the potential-pulsed generation of electrochemiluminescence at a platinum electrode for determination of indole and tryptophan with detection limits of 1 × 10-7 M and linear response to 8 × 10-5 M (C42). Stripping Voltammetry. Armalis et al. studied the influence of hydrodynamic conditions on the sensitivity of stripping analysis in general, with particular application to SW stripping voltammetry at a rotating disk electrode, and recommended the use of optimized rotation rates, which could be as high as 13 000 rpm during deposition for zinc, cadmium, lead, indium, and thallium, but only ∼4000-5000 rpm for gallium. They reported a 10-fold improvement by using potentiometric stripping (C43). (a) Anodic Stripping Voltammetry (ASV). Armalis and Johansson determined a series of trace metals by preconcentrating the sample on an 8-quinolinol column followed by ASV with flow recycling past the working electrode during the electrodeposition step. They estimated that the use of 5 min of enrichment on the precolumn followed by 5 min of recycling during deposition Analytical Chemistry, Vol. 70, No. 12, June 15, 1998

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afforded a ∼50-fold improvement of detection limits compared to 10 min of deposition in a conventional ASV cell, while using half as much sample volume (C44). Lukaszewski et al. determined thallium at levels of 10-11 M in tap and river water using DP ASV coupled to flow injection analysis. Long deposition times up to 2 h were achieved for the lowest detection limit by recirculating the sample past the mercury film wall-jet electrode (C45). Sundd and Prasad used chelation chromatography coupled with DP ASV to fractionate and crudely speciate free ionic, weakly complexed or labile, and strongly complexed or bound metal fractions in river sediments and waters (C46). Mikac et al. made a detailed intercomparison of DP ASV vs gas chromatography with atomic absorption detection for the determination of tetraalkyllead and ionic alkyllead compounds in mussel tissues and natural waters (C47). Ivaska and Kubiak used ASV with sequential injection of sample, reagent, and on-line mercury plating of the thin-film mercury electrode for determination of copper in tap water (C48). Zhou et al. applied fast-scan (15 V/s) ASV in a microflow stream (∼5 mL/min) for determination of cadmium at platinum-based mercury microelectrodes. They obtained detection limits of 0.17 nM with 2-min preconcentration, or 0.19 pg of cadmium ion at 4.9 mL/min, or submicromolar detection limits with a fresh sample obtained every 10 s (C49). Buffle and co-workers evaluated the use of a microelectrode array of mercury-plated iridium microelectrodes for the determination of trace levels of lead and cadmium in river water, with detection limits of 50 pM after 15min preconcentration, with good stability and reproducibility (C50). Lam et al. applied rotating disk voltammetry as well as ASV at a mercury thin-film electrode either bare or coated with Nafion for chemical speciation of lead and cadmium in freshwater containing dissolved organic matter such as fulvic acid. They found that fulvic acids at concentrations (e20 mg/mL) below levels of organic matter found in natural waters measurably affected the voltammetry of cadmium and lead. The Nafion film was very valuable for reducing interferences by blocking transport of large inert metal-fulvic acid complexes, while allowing transport of small metal-fulvic acid complexes to the electrode surface (C51). Rajeshwar and co-workers used a flow stream to determine the composition of an electrodeposited thin-film copper-nickel alloy by chemically stripping the alloy into the flow stream and performing DP ASV at a thin-film mercury electrode downstream to detect the copper, followed by a mercury-coated reticulated vitreous carbon filter to remove any excess copper ions, and finally DP ASV detection of nickel at a downstream detector (C52). Brand et al. determined lead by SW ASV without removal of oxygen at a silver rotating disk electrode, with detection limits of 0.5 nM. Surfactants in tap water adversely affect the voltammograms, necessitating pretreatment of samples by irradiation at 254 nm or by digestion with nitric acid (C53). Kounaves and co-workers reported the successful application of a microelectrode array of iridium-based mercury thin-film microelectrodes for the determination of labile and total (pH 1 cm s-1) using microjet electrode deposition of Cu(0); potential and current scan plus galvanic pulse methods II. EC and EC2 Mechanisms Rh(II) product dimerizes to form 3 different dinuclear species procedure for extraction of kinetic parameters for “C” step from voltammetry in acetonitrile; described as a “concerted EC” mechanism oxidn of reduced folic acid + thiols, and redn of disulfides + folic acid reduction of dinuclear complexes results in metal-metal bond homolysis; reoxidation of fragments regenerates dinuclear species EqCI mechanism studied by cyclic voltammetry and digital simulation main oxidation products are [TaH(CO)4(Ph2P(CH2)2PPH2)] and [TaCl(CO)2(Ph2P(CH2)2PPH2)2] III. EC′ (ECcat) Mechanisms Mn tetrakis(N-methyl-4-pyridyl)porphine-catalyzed oxidation [Ir2(1,8-diisocyanomenthane)4]2+-catalyzed reduction of CO2 Co(II) tetrakis(4-sulfonatophenyl)-b-octabromoporphyrin catalyst electroreduced thiazine dyes used as catalysts semi-fluorescein radicals oxidized by sonochemically generated hydroxyl radicals N-hydroxy-R,R′-iminodipropionate is oxidation catalyst IV. ECE Mechanisms reduction pathway in DMF reduction pathway in acetonitrile

H21 H22 H23 H24 H25

H26 H27 H28 H29 H30 H31 H32

H33 H34 H35 H36 H37 H38 H39 H40

oxidation pathway in acetonitrile variable-temperature study of reduction mechanism, other derivatives also examined reduction at Hg electrodes in strongly acidic media reduction in 1 M NaCl, pH 2.4; faradaic admittance study oxidation pathway oxidation pathway; Au electrode in DMF reduction pathway; other derivatives also studied

H43 H44 H45 H46 H47

oxidation pathway in acetonitrile reduction pathway in DMF; involves ring-opening reaction aqueous reduction; pH range from 4 to 12 reduction studied in sulfate medium

H48 H49 H50 H51

horminone 6-hydroxy-1′,3′,3′-trimethylspiro[2H-1benzopyran-2,2′-indoline] thioselenanthrene

V. DISP Mechanisms DISP1; scanning electrochemical microscopy study oxidation followed by disproportionation of semiquinone radical in acetonitrile; DISP1 at pH 15.5; DISP2 at pH 17.2 oxidation in acetonitrile; electrogenerated semiquinone disproportionates DISP2 mechanism in acetonitrile

catechol violet Cr(N-methyliminodiacetate) Co(II/III) salen Cu(II/I) cyclic tetrathiaethers p-diacetylbenzene (7,12-diphenyl)benzo[k]fluoranthene Fe(H)Cl[P(CH2)2PPh2]3 isonicotinamide Mn 2-mercaptopyridine-N-oxide 3-mercaptopropionic acid 1-methyl-4-methoxycarbonylpyridinium iodide [Pt(H2)(AuPPh3)8]2+ ReOCl(salen) [Ru[N,O-CH3COC(NO)COCH3](bpy)2]+ [Ti4{h5-C5H4(SiMe3)}4](m-O)6

VI. Other Mechanisms ECEC mechanism; aqueous solutions, Hg electrode square scheme analyzed by digital simulation 3-rung ladder scheme; mixtures of DMF and pyridine 3-rung ladder scheme; variable scan rate cyclic voltammetry Laviron surface square scheme; aqueous solution EC2EE mechanism; electrogenerated chemiluminescence EEC oxidation pathway; Ru and Os derivatives also studied ECCE reduction pathway in aqueous media CEE reduction of 1:1 Mn(II) complex EC2E oxidation mechanism in acidic, aqueous media ECC reduction mechanism; aqueous media CEE reduction mechanism CEC mechanism; acacen and salphen derivatives also studied ECEC mechanism; other derivatives also studied EECCEE reduction mechanism

anthracene + phenol caffeic acid

ref

H41 H42

H52 H53 H54 H55 H56 H57 H58 H59 H60 H61 H62 H63 H64 H65 H66 H67 H68 H69 H70 H71

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(b) Reflection: Surface Species. Scherson and co-workers theoretically treated differential reflectance UV-visible spectrometry of adsorbed layers. They discussed the significant changes in spectral shape (peak shifts or new peak appearance as well as polarization differences relative to bulk or normal incidence) with varying incidence angle and substrate for molecular adsorbed layers on metal and graphite electrodes, depending on the interfacial optical constants, and cautioned against cursory interpretation of electroreflectance spectra obtained at other than normal incidence (I20). Gutierrez discussed use of potentialmodulated reflectance spectrometric measurements to detect chemisorbed carbon monoxide and distinguish between linear, bridged, and chemisorbed forms (I21). Feng et al. determined the electrode kinetic parameters of cytochrome c immobilized on an SH(CH2)9COOH self-assembled monolayer on a gold electrode (I22). Fujishima’s group used potential modulation UV-visible absorption and FT-IR reflection spectrometry to identify the transformations of an azobenzene-terminated self-assembled monolayer on an electrode surface (I23). They also studied the isomerization of amphiphilic azobenzene derivatives in a Langmuir-Blodgett film at an electrode surface (I24). Babaei and McQuillan used UV absorption spectroelectrochemical methods to confirm that benzoquinones are the primary oxidation products of hydroquinones in dichloromethane solution, with some water production. An IR band observed at 1713 cm-1 at positive electrode potentials was attributed to end-on adsorbed benzoquinone (I25). (c) Transmission. Flowers and Callender have developed a general-purpose spectroelectrochemical transmittance cell suitable for use with both aqueous and nonaqueous solutions with UV, visible, and infrared spectrometry and spectroelectrochemical applications (I26). The laboratories of Caughey and Elliott have collaborated to investigate the interactions of the metal centers in cytochrome c oxidase in the presence of carbon monoxide, using both visible and infrared spectroelectrochemical measurements. They found evidence suggesting redox-state-linked interaction of iron and copper centers in the enzyme, as well as the apparent existence of two major, independent conformers of the CO complex (I27). Gaillard and Levillain used time-resolved visible spectroelectrochemistry to study the reduction of sulfur (S8) in dimethylformamide, under both thin-layer and semi-infinite diffusion conditions to form a dianion which disproportionates to form S3-. They also offered a new interpretation of a prewave previously attributed to impurities by other authors (I28, I29). Compton and co-workers have described several applications of thin-layer flow cells for UV-visible spectroelectrochemical investigations of reaction mechanisms and kinetics. They described the cell and measured a rate constant of close to 104 M-1 s-1 for the dimerization of the methyl viologen radical cation (I30). They also demonstrated the use of the cell for determining the diffusion coefficients of electrogenerated species by monitoring the transient absorbance response downstream of the working electrode after application of a potential step (I31, I32). They found that the diffusion coefficients of a series of radical cations and anions tended to deviate from the diffusion coefficients of the neutral parent compounds to a degree governed by solvation, with ∼5-15% negative deviation in media such as water but little deviation in acetonitrile (I32). 564R

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Yan and Hupp discussed the application of laser spectroelectrochemical methods for determination of fast heterogeneous electron-transfer rate constants and conduction band edge energies of metal oxide semiconductors, and estimation of approximate redox potentials of short-lived excited-state species (I33). They also investigated interfacial electron-transfer reactivity at dyesensitized titanium dioxide by transient absorbance spectroscopy (I34). Kazanskaya et al. used thin-layer absorption spectroelectrochemical measurements to detect evidence for a conformational change in cytochrome c3 (I35). Malinauskas and Holze found evidence of an EC mechanism for the electrooxidation of Nmethylaniline at an optically transparent electrode (I36). Zheng et al. spectroelectrochemically detected an N-alkyl CoTPP intermediate while investigating the reaction mechanism of alkyl halides with carbon dioxide catalyzed by (5,10,15,20-tetraphenylporphyrin)cobalt (CoTPP) (I37). Infrared Reflectance or Absorbance. Zhang and Lin also carried out studies on a related cobalt(II)-cyanoferrate polymeric film coated on glassy carbon, using FT-IR spectrometry. They found Fe(III)-bound but not Fe(II)-bound terminal CN stretching bands which they interpreted in terms of a possible switch in the lattice structure (I38). Sawtschenko et al. found spectroelectrochemical measurements useful in unraveling the reaction pathways for the reduction (ECE mechanism involving self-protonation) and reoxidation (EC mechanism involving proton loss) of dihydrotetraazapentacene. UV-visible spectroelectrochemical measurements showed that the reduction intermediates could be reversibly reoxidized at sufficiently short times (I39). Sato et al. investigated the potential-dependent orientation and oxidative decomposition of mercaptoalkanenitrile monolayers on gold (I40). Best et al. studied short-lived, highly reduced dithiolene complexes by potential modulation spectroelectrochemical techniques (I41). Lopes and Proenca outlined the general principles of several infrared spectroelectrochemical methods and discussed applications to studies of electrocatalysis (I8). Beden et al. have performed subtractively normalized interfacial Fourier transform infrared spectrometry (SNIFTIRS) and related FT-IR reflectance investigations of the electrocatalytic oxidation of glucose at platinum electrodes and identified reactive intermediates and reaction products (I42). Fawcett and co-workers used SNIFTIRS to probe the composition of the electrochemical double layer at single-crystal Au(100) electrodes in perchlorate media (I43). Zhang and Lin have performed reflectance FT-IR spectroelectrochemical studies at a disk microelectrode array in a thin-layer configuration. They note improvements in ohmic potential drop with this configuration (I44). Several reports have appeared on the spectroelectrochemical investigation of the redox chemistry and electron-transfer kinetics of metallocyanate species, notably ferricyanide and ferrocyanide species and possible intermediates and products. Considerable interest remains in the possible identity of adsorbates, which is not yet firmly established. Pharr and Griffiths have discussed the electrochemistry and identity of solution and adsorbed species using both step-scan (I45, I46) and rapid-scan (conventional) Fourier transform infrared spectrometry (I46) in a thin-layer cell with a sinusoidally modulated electrode potential. They discussed the relative merits of SNIFTIRS, which is a relatively static, slow technique based on difference spectra between two applied

potentials, vs electrochemically modulated infrared spectrometry (EMIRS), which has traditionally involved dynamic potential modulation, but has usually required dispersive spectrometers. The use of a step-scan interferometer enabled the use of EMIRS experiments with an FT-IR instrument, by avoiding intermodulation interferences between the interferometric and potential modulation programs. Osawa et al. have also discussed the use of step-scan FT-IR spectrometry and two-dimensional correlation analysis to study electrode reaction processes (I47). Pharr and Griffiths interpreted the commonly observed decrease in heterogeneous electron-transfer kinetic rate with time in KCl supporting electrolyte as being primarily due to the adsorption of ferrocyanide species, although they also found evidence for formation of a reversibly adsorbed soluble Prussian blue complex (KFe(II)[Fe(CN)6]) during potential cycling if large potential limits are used (I46). Dunphy et al. used visible light and an integrated optical waveguide to study the same reaction (I48). A comparison of the conclusions of these papers is instructive, as it illustrates the complementarity of different approaches as well as the role of differing experimental conditions and initial assumptions in reaching different interpretations of the data. The integrated waveguide approach of Dunphy et al. showed impressive sensitivity, detecting 0.4% of an adsorbed monolayer of methylene blue on a tin oxide electrode which formed an integral part of the waveguide. The sensitivity was ∼104-fold greater than for singlepass transmission, although the approach is currently limited to a single wavelength (I48). Kulesza et al. found derivative chronoabsorptometry particularly valuable for the investigation of the identity of Prussian blue films electrodeposited in electrolytes with various alkali metal cations at gold electrodes. They found that derivative chronovoltabsorptometry provided information not available from pure voltammetry (I49). Kulesza et al. also described use of a twoelectrode, sandwich-type thin-layer cell with FT-IR/attenuated total reflectance at a germanium working electrode to study the spectroelectrochemistry of solid-state Prussian blue with oxidation and reduction of Prussian blue at opposing electrodes (I50). Raman. Campbell et al. used Raman spectroelectrochemistry to identify the reduction of azobenze to hydrazobenzene in selfassembled monolayers of azobenzenebutanethiol and ferrocenylazobenzenebutanethiol on gold electrodes. The ability of the azobenzene moieties to undergo reduction was governed by the collective properties of the densely packed films, which determined whether countercations could enter the film to compensate the charge of the initially formed azobenzene anion radicals, whereas oxidation of the terminal ferrocenyl moieties, which were always accessible to the solution phase, exhibited no such dependence on film conditions (I51). Wu et al. used in situ resonance Raman spectrometry to study the redox chemistry of poly-o-phenylenediamine, which exhibited at least three redox states (I52). Spiro and co-workers carried out a nanosecond timeresolved resonance Raman spectroelectrochemical study on photoexcited Ru(II) porphyrins to investigate where charge was transferred between the metal ion and bound ligands (I53). Lin and Spiro also investigated the structural distortion of the vanadyltetraphenylporphyrin anion radical using resonance Raman spectrometry (I54). Trznadel et al. carried out Fourier transform spectroelectrochemical studies in conjunction with UV-visible-

near-infrared spectroelectrochemical measurements to investigate the redox chemistry of regioregular poly(3-octylthiophene) (I55). Mosier-Boss et al. developed a versatile, low-volume thin-layer cell for in situ surface-enhanced Raman spectroscopy (SERS) and infrared spectroelectrochemical investigations (I56). Brown and Hope used SERS to study the adsorption of gelatin on copper electrodes in sulfuric acid. They were able to demonstrate potential-dependent anion coadsorption, with halide adsorption more prominent at less negative potentials and sulfate at more negative potentials (I57). Luczak et al. studied the adsorption of benzylamine on polycrystalline gold using SERS in conjunction with differential capacity studies (I58). Xiao and Markwell investigated the potential dependence of conformation of nicotinamide adenine dinucleotide using Fourier transform near-infrared and concluded that the detection limits could be improved as much as 3 orders of magnitude with excitation in the near-infrared (I59). Tian et al. were able to show that SERS spectrometry made feasible the investigation of the electrode/electrolyte interfacial structure in the presence of strong hydrogen evolution. They also introduced a new technique, potential-averaged surface-enhanced Raman spectrometry (PASERS), which involves rapid square wave voltage modulation between two potentials and deconvolution to obtain the SERS spectra corresponding to each potential (I60). Simpson and Melendres investigated the temperature dependence of the principal iron (hydr)oxide composition in the corrosion film on iron in aqueous NaOH and borate solutions (I61) and in aqueous carbonate solutions (I62) using SERS spectroelectrochemistry. Weaver’s group combined SERS and infrared spectroelectrochemistry to investigate the adsorption of nitric oxide and carbon monoxide on polycrystalline iridium (I63). Dimerization. Several spectroelectrochemical papers have addressed the subject of dimerization of electroactive species. The combination of spectral with electrochemical measurements is especially valuable in providing evidence of the existence and the properties of dimeric species. The methyl viologen radical dimer was the subject of several papers using various measurement techniques. Lezna and Centeno used spectroelectrochemistry to obtain the spectrum of the methyl viologen radical dimer at mercury film electrodes (I64). They also studied the reduction in the presence of iodide ions and found evidence for flat adsorption of the pyridyl groups and evidence suggesting a possible adsorbed state phase transition which may involve aggregation (I65). Compton and co-workers used a spectroelectrochemical flow cell to measure the dimerization kinetics using UV-visible absorption (I30) and ESR detection (I66, I67) and direct electrochemical measurement of the half-wave potential (I68). Under some circumstances, when the dimerization reaction is essentially rapid and reversible, the ESR method can be essentially blind to the dimerization process (I67). Kepley and Bard found significant dimerization of the methyl viologen radical cation in a reductively electrodeposited viologensiloxane polymer using in situ ellipsometry (I69). Lee et al. used UV-visible-near-infrared and Raman spectroelectrochemistry to characterize dimers and higher aggregates of a series of unsymmetrical viologens and bis(viologens) linked by polymethene chains. They were able to observe three distinct spectral types which they attributed to conventional face-to-face dimers, an obliquely stacked dimer, and higher aggregates (I70). Lee and Analytical Chemistry, Vol. 70, No. 12, June 15, 1998

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co-workers also investigated the monomer/dimer equilibria of a series of 1-methyl-1′-alkyl viologen radical cations with a series of chain lengths Cn from C1 to C10 for the 1′-alkyl group. They found that the extent of dimerization did not change markedly with n for n e 8, but increased rapidly for n > 8, and that high concentrations of R-cyclodextrin could nearly completely suppress dimerization of dibutyl viologen, but not methyloctyl viologen, based on steric hindrance considerations in the inclusion complex (I71). Mortimer and Dillingham investigated the generation of radical cations of viologens with a series of alkyl chain lengths in a Nafion membrane component of an electrochromic electrode and concluded that dimerization increases with alkyl chain length (I72). Lever et al. have also shown that mononuclear chloro(phthalocyaninato)rhodium(III) is reversibly reduced to a monomeric rhodium(II) species which is stable at low temperatures but dimerizes to form several possible rhodium-rhodium-bonded dinuclear species at room temperature. The dimeric species can be reversibly reduced to form anion radical species (I73). Gray and co-workers have spectroelectrochemically determined the dimerization constants of chloro(terpyridine)platinum(II) and its one-electron-reduction product, with a mixed-valence intermediate state. Variable-temperature ESR spectroscopy showed that the first electron transfer was ligand-centered (I74). Flow Cells. Tolmachev et al. theoretically modeled the concentration profile expected in a thin-layer laminar flow cell and showed that the concentration of reactant or stable product adjacent to the cell wall downstream of the electrode differs less than 5% from the surface value for distances of a few micrometers from the wall in practically realizable flow cells. They argued that this could greatly simplify the interpretation of in situ attenuated total reflection-infrared spectrometric measurements (I75). Bewick and co-workers found a thin-layer spectroelectrochemical flow cell useful to maintain a steady-state concentration profile for SNIFTIRS infrared spectroelectrochemical investigations of the electrooxidation of hypophosphite at a nickel electrode. They detected only phosphite ions as the oxidation product and also found some evidence for adsorption of hypophosphite at nickel (I76). Multimode Methods. Heineman and co-workers described a spectroelectrochemical sensor based on an electrode modified with an ion-exchange film with three modes of selectivity: chargeselective partitioning into the film, electrolysis potential, and absorption spectrum. Both inorganic sol-gel films and organic polymer films were successfully used to enrich and selectively detect both cationic and anionic analytes while discriminating against interferents of like or different charge (I77, I78). Johnson and Park used spectroelectrochemistry and rotating ring-disk electrode techniques to study the early stages of aniline polymerization. They found spectroelectrochemical evidence for significant initial formation of benzidine, a tail-to-tail dimer, followed by generation of head-to-tail dimer N-phenyl-p-phenylenediamine and oligomers (I79). Concentration Gradients. Several groups have used spectroelectrochemistry to investigate the “first cycle or sweep effect” observed during the first voltammetric scan in electrogenerated polymers. The effect is observed on reduction of polyaniline (I80) and on oxidation of polypyrrole (I81) and is attributed to ion 566R

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motions in the polymer film, which have a different history on forward and reverse sweeps. Li studied the large overpotential for the first reduction of polypyrrole perchlorate films and observed dramatic changes in the film thickness and morphology (I82). Tezuka et al. investigated the first cycle relaxation effect in polypyrrole films by monitoring time-dependent concentration profiles across the film. They used a UV-visible diode array detector aligned to monitor changes in absorbance parallel to the glass substrate on which the film was initially deposited in the nonconductive state, with the working electrode at one end. In this manner, the effective thickness of the film could be magnified a 1000-fold. A clear propagating phase boundary was observed with spatial resolution of 0.36 mm (I81). Long Optical Path Thin-Layer Spectroelectrochemistry. This area has been relatively quiet recently. A couple of cell designs have been reported, including a demountable cell from the laboratory of Porter, designed for convenient construction and use of delicate substrates in a conventional spectrophotometer cuvette (I83), another demountable cell by Niu and Dong based on inserting two Teflon cell bodies into a conventional cuvette (I84), and a cell from the laboratory of Kirchhoff suitable for luminescence spectroelectrochemistry (I85). Xie et al. also used long optical path thin-layer spectroelectrochemistry to determine Fe and Cu simultaneously as the bipyridine complexes at submicromolar concentrations (I86). Fang et al. reported the use of a long optical path spectroelectrochemical method with illumination parallel to the electrode surface to study the oxidation reaction of acetaminophen to form a free radical which underwent disproportionation (I87). Diffusion Layer Imaging and Concentration Gradient Profiling. Activity in this area has been relatively limited during this reporting period. Shen et al. have developed and tested theory for acoustic generation of transient reflecting diffraction gratings adjacent to a gold thin film on glass, which are suitable for probing the electrical double layer adjacent to the electrode through the potential dependence of thermal and optical properties (I88). Maness et al. used electrochemiluminescence to probe frozen diffusion layers oriented perpendicular to the light beam, although explicit experimental evaluation of the concentration profile was not attempted (I89). Corn’s group measured differential reflectivity during electrochemically modulated surface plasmon spectrometric experiments to probe the electric field profile inside self-assembled zirconium phosphonate multilayer films containing noncentrosymmetric chromophores. They observed evidence of ion and solvent penetration into the films and were able to use interference effects in mixed multilayers of two chromophores to verify retention of spatial order during multilayer deposition (I90). Chemiluminescence and Luminescence. Kirchhoff briefly reviewed luminescence spectroelectrochemistry and described a versatile cell with a long optical path suitable for these experiments (I85). Kirchhoff and co-workers also reported on the thin-layer spectroelectrochemistry and excited-state absorption spectroscopy of rhenium(I) R,R′-diimine complexes (I91). They observed several oxidation states and concluded that both ligand-centered and metal-centered redox processes were involved. Ding et al. performed cyclic voltfluorometry to investigate the emission of Ru(bpy)32+ and its quenching by tetracyanoquinodimethane at the

water-1,2-dichloroethane interface using total internal reflection illumination (I92). Knapp et al. studied photoinduced electron transfer from nucleotides to DNA intercalating viologens by laser flash photolysis and spectroelectrochemistry (I93). Curtis and Wightman reviewed electrochemiluminescence generated at microelectrodes and discussed the advantages of microelectrodes for this type of experiment, including the ability to work at higher frequencies, minimizing adverse side reactions, and at lower ionic strengths, enabling higher ECL emission efficiency (I94). Both Rosenmund and Doblhofer and Pastore et al. investigated the effect of uncompensated ohmic drop on ECL emission, potential dependence, and spatial distribution of emission (I95, I96). Coury’s group investigated the effect of high-intensity ultrasound on an ECL system based on luminol with a ring-disk electrode configuration in generator/collector configuration. They found collection efficiencies as high as 0.164 for an electrode configuration with a value of 0.222 when used as a rotating ring-disk system, but little enhancement of electron-transfer rate constant (I97). Maness et al. used electrogenerated chemiluminescence of excited Ru(II) species generated by reaction of Ru(III) and Ru(I) species to characterize a film of poly[Ru(4-vinyl-4′-methyl-2,2′bipyridine)3(PF6)2] electropolymerized at a platinum interdigitated microelectrode array. The films showed diodelike behavior when concentration gradients of Ru(III), Ru(II), and Ru(I) were formed in solvent-swollen films and then frozen by drying and cooling the films while the microelectrodes were held at specific relative potentials. The diodelike behavior was not observed in films swollen with solvent (I89). Preston and Nieman described an analytical ECL probe based on tris(bipyridyl)ruthenium(II) or luminol which used a fiber-optic light guide and required no exclusion of ambient light and no flow for the determination of glucose at micromolar concentrations (I98). Electrochemiluminescence detectors have been used for several analytical applications, including flow injection immunoassay for atrazine (I99), flowthrough detection of alcohols and carbohydrates (I100), and detection of nucleic acids such as DNA immobilized on an electrode. The latter application was the subject of a patent developed by Bard and Xu (I101). Several groups have also used ECL as a mechanistic tool. Belash and Rozhitskii used ECL to study reaction mechanisms complicated by follow-up chemical steps (I102). Bard and coworkers have made mechanistic and kinetic studies of the anodic coupling of diphenylbenzo[k]fluoranthene (I103) and evaluated the effect of oxygen on the ECL of a linked Ru(bpy)32+-viologen species and methyl viologen. They found a number of identified and unidentified products when ECL is carried out in the presence of oxygen (I104). Ellipsometry and Circular Dichroism. Boher et al. used spectroscopic ellipsometry to characterize both thickness and optical indices of indium tin oxide films. Film quality was evaluated by transparency in the range from 400 to 600 nm. Application of the Drude model to the infrared absorption of the film enabled prediction of the film conductivity (I105). de Souza et al. used spectroscopic ellipsometry and cyclic voltammetry to study the oxidation of nickel and to characterize several of its oxidation products in alkaline solution (I106). Reipa et al. used real-time dynamic spectroscopic ellipsometry in conjunction with

differential capacitance measurements to follow the kinetics of adsorption of putidaredoxin on gold electrodes. The time dependence at short times was in good agreement with expectations for diffusion-controlled adsorption (I107). Kepley and Bard used transient ellipsometry during potential step experiments to characterize charge transport and the effects of solvent swelling on a viologen siloxane polymer. They found that the kinetics of charge transport by electron hopping between oxidized (2+) and reduced (1+) viologen centers fit a diffusion-controlled model during film reduction, with reduction proceeding from the electrode-film interface outward and with film shrinkage of ∼25%. The reoxidation of the film required solvent reswelling, which considerably slowed the kinetics of the process (I69). It seems likely that this phenomenon is closely related to the “first cycle effect” described by other workers for other polymer films (I80, I81). Chandrasekaran et al. used transient ellipsometry to characterize the growth of electrodeposited photoresist films. Initial formation of “pillars” perpendicular to the electrode surface is followed by coalescence to a smooth film above ∼18 nm thickness (I108). Granito et al. have used ellipsometry and polarized optical absorption to probe the orientation of copper and nickel phthalocyanine derivatives in Langmuir-Blodgett films (I109). Noble and Peacock have used circular dichroism spectroelectrochemistry of Ru(bipy)32+ and Os(bipy)32+ to demonstrate localization of the successively added electrons on individual bipyridine ligands in the singly through triply reduced complexes (I110). Porsch et al. have used circular dichroism spectroelectrochemistry to characterize the chiral stereochemistry of electrochemically synthesized polyazulenes and polybiazulene block polymers which undergo significant structural reorganization upon oxidation (I111). Link et al. characterized the “Rieske” [2Fe-2S] center in the bc1 complex and in bacterial dioxygenases by circular dichroism spectroelectrochemistry coupled with cyclic voltammetry using an optically transparent thin-layer electrode cell (I112). Surface-Selective Techniques. Yagi et al. have used threewave mixing including second-harmonic generation and sumfrequency generation to study CO adsorption at platinum (I113). Tadjeddine et al. have used three-wave mixing using visible and infrared wavelengths to study the behavior of cyanide ions at Pt(100) surfaces (I114). A number of groups have exploited surface plasmon phenomena to investigate species on surfaces. In addition to the work of Corn’s group mentioned above (I90), Jung and co-workers have developed an analytical sensor based on electrodeposition of copper and lead on an electrode surface, with surface plasmon resonance detection at ppm levels (I115, I116), using, for example, a working electrode deposited on a fiberoptic element (I115); and Chinowsky et al. have achieved the simultaneous sensing of 500-nm lead and copper ions using a similar setup (I117). A couple of groups have used surface plasmon resonance to study the self-assembly of a biomimetic structure on an electrode surface (I118, I119). Other groups have used the technique to study colloidal and nanosized metal particles in the vicinity of an electrode (I11, I120), and Futamata has used attenuated total reflectance surface plasmon resonance polariton excitation to increase Raman scattering intensity from adsorbates on several types of metal electrodes (I121). Analytical Chemistry, Vol. 70, No. 12, June 15, 1998

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Photoelectrochemistry. Pennarun et al. applied a photoelectrochemical microoptical ring electrode, consisting of a fiberoptic light guide surrounded by a ring electrode, to extract a Stern-Volmer quenching constant for the homogeneous oxidative quenching of photoexcited tris(2,2′-bipyridine)ruthenium(II) by Fe3+, which was in good agreement with values obtained from fluorescence measurements (I122). The approach illustrates that good ideas are continually reincarnated each generation, since the approach is essentially a miniaturization of a design developed by Dennis Johnson in the late 1960s. Oscillations. Honda et al. used time-resolved infrared reflection-absorption spectroelectrochemistry to provide insight on the source of current oscillations during the oxidation of formic acid at a Pt(100) single-crystal electrode. They observed two different types of CO absorption during current oscillations. Because the rate of CO2 production was constant during these experiments, they attributed the oscillations to adsorption of OH species in the presence of CO rather than the traditional view that they result from adsorption coupled with oxidation of CO itself (I123). Electron Spin Resonance (ESR). A number of papers explicitly used ESR as a spectroelectrochemical detection tool. A few examples are cited here. Petr et al. described an electrochemical cell combining ESR and UV-visible spectroelectrochemistry in a single experiment, illustrated by measurements on methyl-substituted p-phenylenediamine (I124). Wilgocki and Rybak described the construction of an ESR microspectroelectrochemical cryostat and its use to detect and characterize the unstable complex cation [OdRe(OEt)Cl2(py)2]+ (I125). Kress et al. coupled ESR and UV-visible spectroelectrochemistry to detect the anion radical and paramagnetic products of a follow-up reaction of the dianion formed in the electrochemical reduction of 2,5diphenyl-1,3,4-oxadiazole (I126). Heilmann et al. coupled ESR with UV-visible and IR spectroelectrochemistry to characterize the radical species generated by the one-electron reduction of some iridium complexes intended to model possible metal-pterin or metal-flavin ligand interactions (I127). Spangler et al. carried out ESR spectroelectrochemical redox titrations of the metal centers of a carbon monoxide dehydrogenase in the presence and absence of a nickel metal center, in conjunction with Moessbauer studies (I128). Hilgers et al. coupled ESR, UV-visible, and IR spectroelectrochemical methods to characterize the reversibly formed one-electron-oxidation and -reduction products of some molybdenum and tungsten alkylpyrazinium complexes (I129). Beden et al. performed ESR spectroelectrochemical measurements on the formation of an oxide layer as a function of potential on an electrodeposited iron film electrode in alkaline solution (I130). Nuclear Magnetic Resonance. Activity in this area is beginning to increase, although it will probably have a long gestation period, as the experiments are quite difficult, even with very high surface area electrodes. Cairns and co-workers have studied the adsorption of 13CO on Pt/C fuel cell electrodes, concluding that there were varying populations of linear and bridge-bonded CO (I131). Wieckowski’s group has looked at much the same system, involving adsorption of 13CO produced from the catalytic oxidation of methanol at platinum black, concluding that the CO is primarily adsorbed on top sites, with the carbon attached to the metal, on one major type of site (I132). 568R

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Terrill et al. have studied gold clusters stabilized by adsorbed layers of 8-16-carbon alkylthiols using proton and carbon NMR (I133). Wieckowski and co-workers have also used 195Pt NMR to study the surface of a graphite-supported platinum electrode (I134). Mass Spectrometry. (a) Differential Electrochemical Mass Spectrometry. As noted earlier, this would be more descriptively called electrochemical membrane inlet mass spectrometry. The most popular approach is still the membrane inlet mass spectrometer commonly referred to as DEMS, which is best suited to volatile and relatively low-polarity substances that can migrate through the membrane and volatilize into the vacuum of the mass spectrometer. In many cases, multiple complementary spectral methods are used simultaneously, e.g., mass spectrometry and infrared spectrometry. Adsorbate molecules are commonly of particular interest. Gootzen et al. have characterized the adsorption of ethanol and 1,2-ethanediol and their products, including CO and CH4 at platinized platinum (I135), adsorption products of C3 alcohols, 1-butanol, and ethene on platinized platinum (I136), and nitric oxide adsorbate layers on platinum (I137), all with accompanying FT-IR measurements. Scherson’s group have studied nitrous oxide generated by nitrite reduction at platinum in perchloric acid media (I138). Pastor and co-workers have looked at competitive adsorption of mixtures of compounds (e.g., formic acid and ethanol) on platinum (I139), or consecutive adsorption of formic acid and propargyl alcohol on platinum (I140), using isotopic labeling to identify the reaction pathways. They have also studied the electrooxidation of propene on gold in acid solution, and the redox behavior of ethyne, ethene, and propene on gold (I141), using DEMS and FT-IR spectrometry (I142). Kolbe and Vielstich also have studied adsorbates formed during the reduction of carbon dioxide and the reoxidation of the reduction products using DEMS (I143). Savinell and co-workers have studied the formation of nitrogen gas during the oxidation of azide ion at carbon electrodes in neutral electrolyte (I144) and the oxidation products of ethanol, 1-propanol, and 2-propanol (I145) or of formic acid (I146) in a polymer electrolyte fuel cell. Anderson and co-workers have demonstrated a potentially very interesting idea of using electrochemical modulation of the sample stream in electrochemical membrane inlet mass spectrometry with correlation analysis to identify volatile components of a mixture (I147). They point out that since different substances have different transit times through the silicone rubber membrane, essentially the membrane acts as a very short chromatographic column, potentially imparting additional selectivity. (Interestingly, they are one of the few groups not using the DEMS nomenclature.) Iwahashi reported an experiment that has elements in common with the Anderson work, although the coupling to the mass spectrometer is quite different, in which they used an electrochemical cell between the injector and the column of a liquid chromatograph. The oxidative products of the electrode reaction were subsequently separated on the chromatographic column and fed to ultraviolet, electron spin resonance, and mass spectrometric detectors for identification (I148). (b) Electrospray Inlet Mass Spectrometry. Several groups have made reports in this area. Cole and co-workers have described an on-line probe assembly for interfacing electrochemi-

cal reaction products to an electrospray ion source and mass spectrometer inlet (I149) and have applied the system to characterize several electrochemical reactions, among which are included the oxidation of diphenyl sulfide and the reduction of nitrobenzene (I150). Van Berkel and co-workers have described the intrinsic electrochemical reactions that occur at the metal capillary of the electrospray source. In some cases, the pH of the solution may decrease by more than 4 units due to production of protons during the oxidation of water in the ion source, with significant consequences for the interpretation of the mass spectrum so obtained (I151). (c) Miscellaneous Mass Spectrometric Interfaces. Several other reports of electrochemical mass spectrometry appeared, including a coupled mass spectrometric/FT-IR study of methanol oxidation at platinum and platinum-ruthenium electrodes (I152), a couple of SIMS studies of electrode surfaces (I153, I154), and a thermal desorption mass spectrometric experiment, in which the electrode is studied in an ultrahigh vacuum system off-line (I155). Two reports appeared on electrochemical deposition of metals for mass spectrometric analysis, in one case to prepare standard materials for glow discharge mass spectrometric analysis (I156) and in another case for determination of heavy metals in biological samples by isotope dilution inductively coupled plasma mass spectrometry (I157). Finally, Henke and co-workers used matrix-assisted laser desorption/ionization (MALDI) mass spectrometry to study self-assembled monolayers deposited on a gold electrode (I158). INSTRUMENTATION General Electrochemical Instrumentation: Hardware. As in the previous review, we begin with some thoughts from Peter Kissinger and colleagues regarding the prospects of electrochemical methodology and equipment becoming practical, accepted, and easy-to-use tools for nonelectrochemists. They point out that progress in this direction is excruciatingly slow, but that there are some hopeful signs (J1). One sign that interest in electrochemical instrumentation is heating up is a paper from the glass industry, which describes an on-line voltammetric detector system for process monitoring of an amber glass production melting tank for iron and other polyvalent metals. Performance is competitive with X-ray fluorescence (J2). A potentiostat was incorporated into a polishing station for mechanical polishing of thin chemically vapor deposited tungsten films to monitor and improve the polishing process (J3). A clear trend in the literature is away from hardware design of specific specialized components with software controlling more and more. Relatively few signal generators and transducers are being published nowadays compared to past years. Most instruments are based on computers or microprocessors and are software-driven. However, Hsueh and Brajter-Toth published a simple low-level current transducer that can readily adapt an existing potentiostat to make measurements with microelectrodes at picoampere currents yet reach scan rates as high as 4000 V/s (J4). Heredia-Lopez et al. described a computer-controlled electroanalytical voltage pulse and triangle wave generator which could generate wave forms for most common electrochemical experiments. Maximum pulse frequency and scan rate were not exceptionally high (J5).

Several stripping voltammetric instruments were described. Desmond et al. described the use of an application-specific integrated circuit (ASIC) to design a voltammetric controller for software-controlled stripping voltammetry (J6). This approach reflects a trend toward the use of general-purpose integrated circuits with some hardware programmability to cut down on the number of components required to design an instrument. Bund et al. described an easily buildable potentiometric stripping voltammetric system (J7). Nawghare et al. described a computerbased instrument for impedance analysis as well as voltammetry and transient experiments (J8). Stastny and Nepozitek described a software-driven virtual instrument for potentiometric stripping analysis, designed for maximum data acquisition rate and minimal cost, with automatic adjustment of optimal sampling rate (J9). Bessant and Saini developed an object-oriented software-controlled approach to a versatile, multitechnique electrochemical instrument (J10). Oduoza et al. described an intelligent, self-optimizing, computer-controlled electrochemical system capable of programming a variety of electrochemical experiments under a Simplex optimization model for multivariate experimental optimization (J11). Stojanovic et al. described a versatile computer-based instrument for flexible three-dimensional voltammetry, which can interface to control most potentiostats and enables exploitation of not only current and potential but also time-dependent information, particularly in a variety of pulse-based voltammetric experiments, with complex data analysis capability (J12). Ruan et al. reported an instrument for constant-current stripping voltammetry based on the second reciprocal derivative of potential vs time (J13). Ekkad and Huber described a coulometer for monitoring residual sulfite after water dechlorination (J14). Reay et al. described a portable microfabricated electrochemical analysis system consisting of a single-chip potentiostat and microcontroller, suitable for field use, which is capable of controlling an array of thin-film mercury microelectrodes on a microfabricated iridium microelectrode array device (J15). Paeschke et al. described another computer-controlled voltammetric multichannel instrument capable of independently controlling the potential of up to 16 electrodes and also capable of working with interdigitated microelectrode arrays on a microchip. The device was capable of simultaneously carrying out pulse and linear sweep experiments, and the sensor module was suitable for use in a flow channel (J16). Several other groups reported instruments suited for flow detection. Sturrock and O′Brien described a computer-controlled voltammetric instrument with automatic programmed baseline compensation which is particularly useful for flow injection and liquid chromatographic experiments where the baseline can change dramatically during the course of one experimental run, especially for solvent gradient runs. Baseline compensation allows a flatter baseline while allowing greater current resolution and a wider dynamic range with better peak definition (J17). Hissner et al. reported on an electrochemical precolumn preconcentrator for ion chromatography (J18). Huang et al. reported on an online flow injection analysis system with a wall-jet detector for glucose monitoring during fermentation (J19). Hoffmann and Rapp described an integrated microanalytical system with potentiometric detection based on field effect transistors (J20), although Analytical Chemistry, Vol. 70, No. 12, June 15, 1998

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Table 9. Electrochemical Cells experiment

analyte/application

remarks

ref

working electrode sputtered onto capillary tip; numerous metals feasible; also enzyme-modified self-guiding electrode holder enables rapid detector electrode positioning at capillary tip without micropositioners or microscope hanging mercury drop electrode; 60 samples/h; on-line UV organic destruction; standardization channel patent; rotating mercury-coated graphite electrode; detection limit 0.03-0.3 ppb thin-layer radial flow detector; split disk; 8 independent electrode sectors, pie-shaped; mercury thread electrode; modified with hydrophilic dialysis membrane novel gold microelectrode array from IC chip; 60-90 samples/h peristaltic pump couples to fermentation reactor; dual-injection valvesdilution or standardization jet ring electrode; renewable solid support with glucose oxidase enzyme catalyst; peroxide detection; linear range 0.1-5 mM wall-jet detector; microliter active volume; large solution volume; postcolumn medium exchange

J47

field effect transistor sensors; complete analytical system in a small package; self-calibration

J20

Flow Cells capillary electrophoresis; amperometric detector capillary electrophoresis; amperometric detection

dopamine, catechol; carbohydrates; glucose misc analytes

cathodic stripping voltammetry

metals in natural water

flow (batch) injection; stripping voltammetry flow amperometric detector

metals analysis

flow injection analysis

lead determination

flow injection analysis, amperometric detection

copper in cane sugar spirit

mixture analysis

glucose in fermentation reactor glucose determination flow injection analysis; highperformance liquid chromatography integrated microanalytical system

abrasive stripping voltammetry; solid-state electrochromism biosensor; amperometric detector enzyme electrode differential pulse voltammetry electrochemical detection electrochemiluminescence, no electrolyte added high pressure; voltammetry implantable biosensor in situ scanning tunneling microscopy; voltammetry

nitrobenzene derivatives ion analysis

Stationary Cells silver octacyanotungstate(IV) and microscopic screening for electrochromism; silver octacyanomolybdate(IV) voltammetry creatinine in blood serum; microfabricated (thick, thin film); selective vs ascorbic acid, bienzyme sensor; polyimide foil substrate; uric acid, acetaminophen cellulose acetate/polyurethane membranes improve selectivity NOx in gas mixture patent; electrocatalysts on working, auxiliary electrodes morphine auxiliary electrode coated with polypyrrole; longer linear range, 6× reduction in current noise miniature cell microlithographic fabrication; microvolume, submicrometer interelectrode gaps; arrays possible high pressure e0.8 GPa practical advice on electrode preparation, maintenance glucose; in vivo glucose oxidase enzyme electrode; cellulose triacetate, polycarbonate, Nafion diffusion control layers; linear to >25 mM glucose Co film on Cu(001) surface in situ STM on electrode surface

photoelectrochemical solar cell; photosensor; chemical sensor rotating disk electrode

photoactive substances

subnanoliter volume analysis; single living cell studies

single living cells; response to hormones and metabolic insult

electrodeposition

patent; microfabricated; variety of configurations feasible demountable electrode without emptying cell; gas sealing; electrodeposition on flat substrates micromachined cell; subnanoliter volumes; must deal with solvent evaporation, biocompatibility

J48 J49 J50 J51 J52 J53 J19 J54 J55

J56 J57

J58 J59 J60 J61 J62 J63 J64 J65 J66

Spectroelectrochemical Cells spectroelectrochemistry electron spin resonance far-infrared long optical path long optical path reflection

Re complex; low-temperature ESR synchrotron radiation source; interfacial structure determination UV-visible, thin-layer; long optical path for better sensitivity UV-visible, thin-layer; long optical path for better sensitivity nickel octaethylporphyrin dianion

the extension to amperometric detection should be straightforward. Matysik (J21) and the Baldwin group (J22) have reported improved amperometric detectors in capillary electrophoresis. Several groups described electrochemical biosensor instruments, including an amperometric biosensor based on a three570R

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low temperature; nonaqueous solution discuss precautions needed for reliable, reproducible results easily assembled in conventional cuvette; suitable for delicate electrode materials easily assembled in conventional cuvette; wide variety of electrode materials, solvents feasible reflection mode; thin-layer or thick; careful sealing allows work in volatile solvents, e.g., liquid SO2

J67 J68 J69 J70 J71

channel potentiostat with a disposable, thick-film multielectrode sensor unit on a single substrate (J23); an in vivo, rechargeable glucose biosensor based on an oxygen electrode and dual potentiostats (J24); an integrated sensor-telemetry system designed for in vivo applications but tested in vitro (J25); and an

Table 10. Electrodes electrode description array, 7 micropipetss6 surrounding central axis array, gold microdisks; potentially individually controlled or interdigitated array, randomly distributed, single potential array, gold microelectrodes with irregular nanostructure; composite biosensor array, metal, semiconductor nanowire electrodes array, carbon microelectrodes array, interdigitated microelectrodes; carbon array, interdigitated microelectrodes; carbon; 2-µm spacing array, iridium microelectrodes; single potential array, line microelectrodes for continuous electrophoresis; 100 Pt electrodes, 5-µm spacing array, silver microelectrodes for Clark oxygen membrane electrode array, interdigitated gold microelectrodes array or individual carbon nanoelectrodes, bare or metallized array, interdigitated microelectrodes or independent

composite/microelectrode array, carbon in sol-gel; enzyme biosensor composite/microelectrode array, glucose enzyme biosensor on rhodium-modified porous ceramic/carbon composite composite/microelectrode array, metal paste biosensor composite/microelectrode array, rhodium-modified carbon for peroxide detection composite/microelectrode array, shavable carbon paste composite/microelectrode array, glucose biosensor general overview of screen-printed electrochemical sensor fabrication composite electrode, carbon modified with metal phthalocyanines

macro- or microelectrode, ruthenium dioxide macro- or microelectrode, silver, silver chloride macroelectrode, Ag/AgCl reference electrode macroelectrode, glucose enzyme biosensor on Pt black/polypyrrole electrode

fabrication method

remarks

Array: Macroencapsulation pipet pulling, borosilicate spatial probe for extracellular iontophoresis glass and intracellular recording; diffusion profiles; adaptable to amperometric electrodes slice integrated circuit chip in separation between microdisks g10× half, expose gold interconnect diameter; little diffusional crosstalk; relatively wires as electrodes easily, inexpensively fabricated Array: Pinholes desorption of self-assembled monolayer of hexadecylthiolate by cyanide; pinhole formation vapor deposit gold on substrate through polymer latex sphere mask layer; liftoff mask nonlithographic electrodeposition in porous alumina templates

single potential; average size of active sites calculated from experiment agrees with size observed from copper deposition immobilize antibodies, enzymes, recognition units on bare areas masked by latex spheres single-electron tunneling observable; periodic conductance oscillation, current staircase observed

Array: Microfabrication microfabrication + good adhesion, properties; robust, reliable, micromachining; sputtered good electrochemical performance carbon film microfabrication; carbon planar array; HPLC flow detector; may use electrode imprinted molecular template for selectivity microfabrication; sputtered planar array; measure 50 nM-100 µM dopamine carbon patterned in O2 plasma; microfabrication; electroplated with mercury microlithography/micromachining microfabrication; dry polypyrrolidone electrolyte; solid-state fabrication microfabrication; X-ray lithography electron beam deposition in electron microscope; gaps less than 5 nm; may coat with metal laser ablation of continuous gold film, with patterned self-assembled monolayer deposition

can deposit/strip mercury film g10 times; square wave anodic stripping of river water: LOD 50 pM (15-min preconcentrated) planar array; channels e8 µm thick; electrophoresis; nonuniform sensitivity; potentially individually controlled or interdigitated biological oxygen demand sensor, yeast cells vs bare electrode; kept dry until use; long shelf life SAW device with 250-nm line widths

J72 J53, J73

J74 J75 J76

J77 J78 J79 J80 J81 J82 J83

study electron transport of single molecules or metal nanoclusters

J84

fabricate interdigitated microelectrode array; 1 set of electrodes modified by active antibody, other resists protein adsorption

J85

Composite Electrode screen printing - sol-gel carbon one-step fabrication, suitable for mass thick film plus enzyme, other production; easily modified, controllable structure, components enzyme kinetics composite porous organically polishable to renew; detects hydrogen peroxide; modified silicate composite, porosity facilitates oxygen permeation from inside with enzyme incorporation electrode, even in O2-free solutions; long-term stability platinum or silver paste with simple fabrication; renewable surface; enzyme components glucose sensor screen printing on polyester film solvent-resistant materials; suitable for biosensors carbon paste

ref

scraper blade renews surface with submicrometer precision sol-gel dispersion of graphite polishable, integrated construction with many with redox enzymes features built in by choice of components Electrodes: Screen Printed screen printing discuss fabrication techniques, electrode processes employed; some applications discussed screen printing, incorporating hydrogen peroxide sensor; catalytic with cobalt, manganese, and iron 700-900-mV reduction of overpotential phthalocyanine redox mediator modifiers Electrodes: Miscellaneous screen printing, thick-film used for pH electrodes, but pH measurement technology affected by reductants; usable for amperometry screen printing on ceramic plate miniaturizable, can be combined with other electrodes on same device pulse oxidation of silver wire long-term stability in human blood serum; in chloride media potential constant (e2 mV) for >600 measurements layer-by-layer casting on glutaraldehyde-cross-linked outer gelatin layer; polypyrrole film substrate linear to 80 mM when covered with polycarbonate membrane; working life several weeks, shelf life >2 yr

J86 J87

J88 J89 J90 J91, J92

J93 J94

J95 J96 J97 J98

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Table 10. (Continued) electrode description macroelectrode, gold film on flexible Teflon substrate; enzyme biosensor macroelectrode, lactate enzyme biosensor on Pt black/polypyrrole electrode microelectrode, glucose enzyme biosensor on gold electrode microelectrode, boron-doped CVD diamond microelectrode, carbon paste microelectrode, cylindrically etched carbon fiber microelectrode, dual disk microelectrode, dual pair microelectrode, gold microbead on glass micropipet tip

microelectrode, gold nanoparticles self-assembled on glass micropipet tip microelectrode, microoptical ring; photoelectrochemical microelectrode, platinumelectroplated gold; lactate oxidase enzyme biosensor microelectrode, STM tip electrodeposited with polyaniline, Cu, or Tl2O3 clusters

fabrication method

ref

Electrodes: Miscellaneous (Continued) vapor-deposited gold on plasmagood adhesion, reproducibility; used as glucose modified Teflon substrate biosensor with glucose oxidase/ferrocene catalysis

J99

layer-by-layer casting on polypyrrole film substrate

J100

glutaraldehyde-cross-linked outer gelatin layer; working life 2 mo; shelf life 1 yr at room temp; 2 yr at -18 °C

Microelectrodes: Miscellaneous recessed gold microelectrodes; linear to 50 mM glucose; Nafion barrier add enzymes and mediators discriminates against anions microwave plasma chemical expose diamond by mechanical polishing vapor deposition on etched or chemical etching of glass tungsten wires; sealed in glass carbon paste deposited in sigmoidal voltammograms, quickly achieved microholes at tips of chemically steady-state current etched microdisk electrodes sealed in glass capillary; etch tip diameters as small as 0.6 µm; can be renewed fiber exposed at tip; insulate with by cutting polymer-covered tip back; studies of electrophoretic paint deposition single-cell secretions double-barreled glass capillary generator/collector experiments electron beam lithography, 5-70-nm electrode separation, possible dual metal electrodes single-molecule experiments sintering of gold microbeads in use metal micropowder, 1.5-3.0-µm gold glass micropipet tip; polish on beads, final diameter 2-9 µm; use aqueous beveler with conductivity monitor electrolyte rather than metal contact to reduce noise and microphone to indicate first contact self-assembly of gold self-assembly on glass micropipet tip to form nanoparticles with 1-30-µm-diameter microelectrode, 1,9-nonanedithiol on glass roughly hemispherical micropipet tip fiber-optic waveguide with thin photoelectrochemistry, microscale ring electrode deposited on fiber wall microfabrication on Kapton inner electropolymerized layer inhibits polyimide foil electrode fouling; outer diffusion barrier enhances linear range electrodeposition on modified STM tip properties platinum-iridium microelectrode

electrochemical catecholamine sensor for real-time feedback and control of an artificial heart system (J26). Several groups reported field-portable or remotely operable electrochemical instruments suitable for environmental screening or on-site monitoring. Wang et al. reported a remote potentiometric stripping sensor system based on a gold microelectrode that can be operated on a cable ∼30 m remote from the controlling instrumentation and has been successfully used for environmental monitoring in a groundwater well and on shipboard (J27). Wang has also written a review on remote electrochemical sensing (J28). Herdan et al. reported on field evaluations of an array of mercury thin-film electrodes on a microlithographically fabricated array of iridium contacts, with a portable minipotentiostat. Parts-per-billion levels of several heavy metals were successfully determined using square wave anodic stripping voltammetry (J29), with sufficient accuracy to be useful for field screening. Schmidt has reported a hand-held potentiometric stripping analyzer with ppb detection limits (J30). Achterberg and Van den Berg developed a voltammetric instrument for automated monitoring of Cu, Mn, and Zn in the Irish Sea (J31). Several reports discussed instrumentation for spatial analysis based on electrochemical methodology, such as scanning probe microscopy and scanning electrochemical microscopy. Three instruments for scanning tunneling microscopy in situ at an electrode in solution were reported (J32-J34). Bard et al. presented a review of scanning electrochemical microscopy which included a discussion of instrumental considerations (J35). 572R

remarks

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J101 J102 J103 J104 J105 J106 J107

J108

J109 J110 J111

Several groups reported instrumentation systems interfacing electrochemical instrumentation to several types of spectrometric systems. Schroder and Scholz described a diffuse reflectance spectroelectrochemical system designed to permit microscopic examination of solid particles immobilized on an electrode (J36). Faguy and Marinkovic described a new infrared reflection spectroelectrochemical accessory (J37). Zhuang and Lu reported a spectroelectrochemical system for in situ coupling of time-resolved ESR spectroscopy with electrochemical reactions (J38). Finally, Cumpson has described a new design for a quartz crystal microbalance which dramatically reduces (20×) the sensitivity of the quartz crystal to deposition on portions of the crystal other than the electrode surface, by redesigning the electrode mass distribution, contrary to some theories about fringing fields at the electrode periphery (J39). Chemometrics and Calibration. Just as software and computer control are playing an increasingly important role in driving the hardware of instrumentation and data acquisition, this trend is also very apparent in the area of data analysis. Discussion is restricted to papers that deal with data acquisition and calibration during the measurement process, rather than workup of data after the analytical measurements are completed. Jagner et al. described a method for automatic analyte current determination for a series of heavy metals in anodic coulometric stripping potentiometry on a gold film electrode, with detection limits of ∼11 nM for monovalent and ∼3 nM for trivalent ions, with mass detection limits of 4.5-28 pg (J40). Easwarakhanthan described

a numerical method for calibration of the angle of incidence of the angle of incidence in ellipsometry (J41). Talaie et al. described use of an integrated artificial neural network for data acquisition and signal processing for a conducting polypyrrole-based formate biosensor (J42). The approach, which allows extraction of analytically useful information from data that at first glance appear irreproducible (J43), was applied to determine formate concentration with a polypyrrole-conducting polymer biosensor (J42). Long-term calibration and drift are very serious problems for many long-term experiments. Several groups have discussed approaches to this problem. Defernez and Wilson addressed means of minimizing the effect of instrumental instabilities on the long-term validity of data, with particular application to spectrophotometric instrumentation, e.g., infrared spectrometers, such as used in numerous spectroelectrochemical experiments involving measurement of small differences in large signals (J44). Two groups addressed this general problem for the specific case of automated continuous monitoring systems for dissolved oxygen using Clark-type membrane electrodes. Sun et al. successfully demonstrated a measurement system for water quality monitoring in a water system with varying chlorination levels. The calibration procedures enabled continuous adjustment of the system as conditions varied for reliable, continuous, unattended fieldmonitoring periods of 70 days (J45). Hesse and Voss addressed the problem of long-term calibration of an oxygen electrode for sterile fermentation technology, where in-line calibration must be achievable over long-term periods without endangering sterility by removing and reintroducing the probe to the system (J46). Electrochemical Cell Designs. A number of electrochemical cell designs were reported for a wide variety of applications. The cells can be classified according to their use in flow systems, stationary systems (or in some cases unspecified systems, since many cell designs can be adapted for flow use), or spectroelectrochemical systems. These are summarized in Table 9. Within a category, cells are listed alphabetically based on the type of experiment for which they are designed. Electrode Designs. A wide variety of electrode designs were reported, with a large number of approaches described to the fabrication of microelectrodes and microelectrode arrays. Many electrode fabrication techniques are described, but most can be reduced to one of three general strategies. The first strategy often simply involves a miniaturization of classical electrode fabrication techniques, particularly sealing in glass capillaries or related supports. Variations on this strategy include depositing a thin film on a substrate and then sealing the film edge-on between two insulators or laying out conductors on a substrate followed by encapsulation with epoxy or glass sealing. The second strategy is based on thin-film microfabrication technologies, using techniques such as microlithography for patterning and developing electrode patterns, often on substrates such as silica, which may have been pretreated by deposition of an insulator such as SiO2 or Si3N4, and possibly an adhesionpromoting underlayer such as a thin film of chromium, tungsten, or titanium-tungsten. Although a variety of electrode materials can be fabricated by this approach, until recently mostly electrode materials such as gold and platinum were favored. Several examples of carbon-based electrodes with excellent properties are

cited here. This approach is the most flexible and often the best choice for microelectrodes or microelectrode arrays of extremely small dimensions or small interelectrode gaps and potentially can be adapted to economical large-scale production, although the problem of access to fabrication facilities can be a problem for individual researchers and costs can be high in small quantities. The third technique is based on a spatially coarser technology, thick-film technology, typically fabricated by screen printing techniques which are a more sophisticated cousin of T-shirt screen printing enterprises. Printing technology is very inexpensive and lends itself to production of large numbers of devices at low cost. Inks are available for fabrication of a wide variety of metallic and carbon-based electrodes. Commercial assay kits using some of these screen-printed electrode materials for home testing already are widely distributed. Finally, there are a few scattered examples of alternative approaches, ranging from induced pinhole formation in selfassembled monolayers to expose electrode active sites to slicing open a commercial integrated circuit package to exploit internal gold interconnection wires as electrode components of a microelectrode array. Electrode designs are summarized in Table 10. Designs are classified on the basis of fabrication methodology. Within a category, they are arranged according to type, e.g., array, macroelectrode, or microelectrode, and within each subcategory they are arranged alphabetically. James L. Anderson is Professor of Chemistry at the University of Georgia. He received his B.A. in chemistry from Kalamazoo College in 1967, and his Ph.D. in Analytical Chemistry at the University of Wisconsin in 1974 under the guidance of Irving Shain. After a postdoctoral appointment in the laboratory of Theodore Kuwana at Ohio State University, he was an Assistant Professor of Chemistry at North Dakota State University from 1975 to 1979, when he moved to the University of Georgia. His research interests are in the general area of electroanalytical chemistry and include electrochemical investigations of environmental redox processes in the water and soil environment, electron-transfer kinetics from both experimental and theoretical perspectives, electrochemical flow detectors, and spectroelectrochemistry. Louis A. Coury, Jr., is Director of Research at Bioanalytical Systems, Inc., West Lafayette, IN. He received a B.S. in chemistry from Miami University, Oxford, OH in 1982 and a Ph.D. in analytical chemistry from the University of Cincinnati in 1988, under the direction of William Heineman. From 1988 to 1990, Coury was a postdoctoral associate with Royce Murray at the University of North Carolina at Chapel Hill. Prior to joining Bioanalytical Systems in January 1998, Coury spent 7 and 1/2 years on the faculty at Duke University. He was awarded the Society for Electroanalytical Chemistry Young Investigator Award in 1996 and served as American editor of the international journal Ultrasonics Sonochemistry from 1996 to 1997. In 1998, Coury was appointed editor of the journal Current Separations. Johna Leddy is currently an Associate Professor of Chemistry at the University of Iowa. She received a B.A. from Rice University in 1978 and a Ph.D. from the University of Texas in 1984, working in the laboratory of Allen Bard. She was a postdoctoral associate at Los Alamos National Laboratory in the Fuel Cell Program in 1986, following which she was on the faculty at Queens’ College of the City University of New York. Among other activities, Leddy serves as Secretary-Treasurer of the Physical Electrochemistry division of The Electrochemical Society, and is an editorial board member for Critical Reviews in Analytical Chemistry.

LITERATURE CITED INTERNET RESOURCES, BOOKS, AND REVIEWS (A1) Anderson, J. L.; Bowden, E. F.; Pickup, P. G. Anal. Chem. 1996, 68, 379R-444R. (A2) The Electrochemical Science and Technology Information Resource. http://electrochem.cwru.edu/estir/. (A3) The American Chemical Society. http://www.acs.org/. (A4) The University of Waterloo Scholarly Societies Project. http: //www.lib.uwaterloo.ca/society/.

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(A5) Will Science Publishing Perish? http://pubs.acs.org/journals/ wspp/cover.html. (A6) Laboratory Techniques in Electroanalytical Chemistry, 2nd ed.; Kissinger, P. T., Heineman, W. R., Eds.; Marcel Dekker: New York, 1996. (A7) Fisher, A. C. Electrode Dynamics; Oxford University Press: New York, 1996. (A8) Compton, R. G.; Sanders, G. H. W. Electrode Potentials; Oxford University Press: New York, 1996. (A9) LaCourse, W. R. Pulsed Electrochemical Detection in HighPerformance Liquid Chromatography; Wiley: New York, 1997. (A10) Chemical Analysis: Modern Techniques in Electroanalysis; Vany´sek, P., Ed.; Wiley: New York, 1996; Vol. 139. (A11) Electroanalytical Chemistry; Bard, A. J., Rubinstein, I., Eds.; Marcel Dekker: New York, 1996; Vol. 19. (A12) Interfacial Electrochemistry; Schmickler, W., Ed.; Oxford University Press: New York, 1996. (A13) Budevski, E.; Staikov, G.; Lorenz, W. J. Electrochemical Phase Formation and Growth: An Introduction to the Initial Stages of Metal Deposition; VCH: New York, 1996. (A14) Solid-Liquid Electrochemical Interfaces; Jerkiewicz, G., Soriaga, M. P., Uosaki, K., Wieckowski, A., Eds.; ACS Symposium Series 656; American Chemical Society: Washington, DC, 1996. (A15) Topics in Current Chemistry, Electrochemistry VI. Electroorganic Synthesis: Bond Formation at Anode and Cathode; Steckhan, E., Ed.; Springer-Verlag: New York, 1996; Vol. 185. (A16) Advances in Electrochemical Science and Engineering; Alkire, R. C., Gerischer, H., Kolb, D. M., Tobias, C. W., Eds.; VCH Publishers: New York, 1996; Vol. 5. (A17) The Plenum Publishing Corp. http://www.plenum.com/. (A18) Electroactive Polymer Electrochemistry: Part 2, Methods and Applications; Lyons, M. E. G., Ed.; Plenum Press: New York, 1996. (A19) Handbook of Biosensors and Electronic Noses: Medicine, Food, and the Environment; Kress-Rogers, E., Ed.; CRC Press: Boca Raton, FL, 1997. (A20) Biosensor and Chemical Sensor Technology: Process Monitoring and Control; Rogers, K. R.; Mulchandani, A.; Zhou, W., Eds.; ACS Symposium Series 613; American Chemical Society: Washington, DC, 1995. (A21) Eggins, B. R. Biosensors: An Introduction; Wiley: New York, 1996. (A22) Bioelectrochemistry: Principles and Practice. Experimental Techniques in Bioelectrochemistry; Brabec, V., Walz, D., Milazzo, G., Eds.; Birkha¨user Verlag: Basel, Switzerland, 1996; Vol. 3. (A23) Bioelectrochemistry: Principles and Practice. Bioenergetics; Gra¨ber, P., Milazzo, G., Eds.; Birkha¨user Verlag: Basel, Switzerland, 1997; Vol. 4. (A24) Bard, A. J.; Fan, F.-R. F. Acc. Chem. Res. 1996, 29, 572-578. (A25) Mirkin, M. V. Anal. Chem. 1996, 68, 177A-182A. (A26) Borgwarth, K.; Ricken, C.; Ebling, D. G.; Heinze, J. Ber. BunsenGes. 1995, 99, 1421-1426. (A27) Bard, A. J.; Fan, F. F. Anal. Sci. Technol. 1995, 8, 69A-74A. (A28) Mandler, D.; Meltzer, S.; Shohat, I. Isr. J. Chem. 1996, 36, 73-80. (A29) Bard, A. J.; Cliffel, D. E.; Demaille, C.; Fan, F. F.; Tsionsky, M. Ann. Chim. (Rome) 1997, 87, 15-31. (A30) Gewirth, A. A.; Niece, B. K. Chem. Rev. 1997, 97, 1129-1162. (A31) Dakkouri, A. S.; Dietterle, M.; Kolb, D. M. Festkoerperprobleme 1997, 36, 1-31. (A32) Ge, M.; Thornton, J. T. Am. Lab. 1997, 29, 28-32. (A33) Li, J.; Wang, E. Electroanalysis 1996, 8, 107-112. (A34) Kurochkin, I. N. Adv. Biosens. 1995, 3, 77-109. (A35) Allongue, P. NATO ASI Ser. 1995, 288, 45-67. (A36) Peter, L. M. Philos. Trans. R. Soc. London 1996, 354, 16131625. (A37) Ocko, B. M.; Magnussen, O. M.; Wang, J. X.; Adzic, R. R. NATO ASI Ser. 1995, 288, 103-19. (A38) Schultze, J. W.; Kudelka, S. Electrochem. Soc. Interface 1997, 6, 28-31. (A39) Weaver, M. J. J. Phys. Chem. 1996, 100, 13079-13089. (A40) Kautek, W.; Geuss, M.; Sahre, M.; Zhao, P.; Mirwald, S. Surf. Interface Anal. 1997, 25, 548-560. (A41) Holze, R. J. Prakt. Chem./Chem.-Ztg. 1996, 338, 293-302. (A42) Villegas, I.; Weaver, M. J. Electrochim. Acta 1996, 41, 661673. (A43) Korzeniewski, C. Crit. Rev. Anal. Chem. 1997, 27, 81-102. (A44) Beden, B. Mater. Sci. Forum 1995, 192-194 (Electrochemical Meth-90). (A45) Bain, C. D. Biosens. Bioelectron. 1995, 10, 917-922. (A46) Gamboa-Aldeco, M. E.; Franaszczuk, K.; Wieckowski, A. In Handbook of Surface Imaging and Visualization; Hubbard, A. T., Ed.; CRC: Boca Raton, FL, 1995; pp 635-646. (A47) Horanyi, G. Rev. Anal. Chem. 1995, 14, 1-58. (A48) Wu, J.; Day, J. B.; Franaszczuk, K.; Montez, B.; Oldfield, E.; Wieckowski, A.; Vuissoz, P.; Ansermet, J. J. Chem. Soc. 1997, 93, 1017-1026. (A49) Janata, J.; Josowicz, M. Anal. Chem. 1997, 69, 293A-296A. (A50) Stratmann, M.; Furbeth, W. Comm. Eur. Communities 1997, EUR 16490, 59-90. (A51) Burleigh, T. D. New Technol. Charact. Corros. Stress Corros. 1996, 267-273. 574R

Analytical Chemistry, Vol. 70, No. 12, June 15, 1998

(A52) Tucceri, R. I.; Posadas, D. Curr. Top. Electrochem. 1994, 3, 423-440. (A53) Parsons, R. Solid State Ionics 1997, 94, 91-98. (A54) Trasatti, S.; Doubova, L. M. J. Chem. Soc., Faraday Trans. 1995, 91, 3311-3325. (A55) Fawcett, W. R. Electrochim. Acta 1996, 42, 833-839. (A56) Nazmutdinov, R. R.; Shapnik, M. S. Electrochim. Acta 1996, 41, 2253-2265. (A57) Halley, J. W. Electrochim. Acta 1996, 41, 2229-2251. (A58) Pajkossy, T. Heterog. Chem. Rev. 1995, 2, 143-147. (A59) Aldaz, A.; Morallon, E.; Vazquez, J. L. Curr. Top. Electrochem. 1994, 3, 387-408. (A60) Thompson, J. S. Chemtracts 1997, 10, 376-384. (A61) Partenskii, M. B.; Dorman, V.; Jordan, P. C. Int. Rev. Phys. Chem. 1996, 15, 153-182. (A62) Benedetti, L.; Fontanesi, C. Curr. Top. Electrochem. 1994, 3, 61-76. (A63) Stradins, J. Electrochim. Acta 1996, 42, 731-736. (A64) Vany´sek, P. Electrochim. Acta 1995, 40, 2841-2847. (A65) Kihara, S.; Yoshida, Y.; Shirai, O.; Maeda, K. Mem. Fac. Eng. Des. 1996, 44, 33-66. (A66) Kihara, S. Curr. Top. Electrochem. 1994, 3, 19-42. (A67) Brevet, P. F.; Girault, H. H. In Liquid-Liquid Interfaces. Theory and Methods; Volkov, A. G., Deamer, D. W., Eds.; CRC: Boca Raton, FL, 1996; pp 103-137. (A68) Volkov, A. G.; Gugeshashvili, M. I.; Deamer, D. W. Electrochim. Acta 1995, 40, 2849-2868. (A69) Senda, M. Anal. Sci. Technol. 1995, 8, 95A-100A. (A70) Rusling, J. F. Colloids Surf. 1997, 123-124, 81-88. (A71) Rusling, J. F.; Zhou, D.; Gao, J. Proc.-Electrochem. Soc. 1997, 97-6, 137-149. (A72) Abbott, N. L. Prog. Colloid Polym. Sci. 1997, 103, 300-306. (A73) Rusling, J. F.; Suib, S. L. Adv. Mater. 1994, 6, 922-930. (A74) Gerlache, M.; Kauffmann, J. M.; Quarin, G.; Vire, J. C.; Bryant, G. A.; Talbot, J. M. Talanta 1996, 43, 507-519. (A75) Rusling, J. F. Prog. Colloid Polym. Sci. 1997, 103, 170-180. (A76) Bizzotto, D.; Lipkowski, J. Prog. Colloid Polym. Sci. 1997, 103, 201-215. (A77) Majda, M. Thin Films 1995, 20, 331-347. (A78) Zhong, C.-J.; Porter, M. D. Anal. Chem. 1995, 67, 709A-715A. (A79) Mandler, D.; Turyan, I. Electroanalysis 1996, 8, 207-213. (A80) Bilewicz, R. Ann. Chim. (Rome) 1997, 87, 53-66. (A81) Kaifer, A. E. Isr. J. Chem. 1997, 36, 389-397. (A82) Kaifer, A. E. Prog. Colloid Polym. Sci. 1997, 103, 193-200. (A83) Maskus, M.; Tirado, J.; Hudson, J.; Bretz, R.; Abrun ˜a, H. D. NATO ASI Ser. 1996, 485, 337-353. (A84) Fox, M. A.; Wolf, M. O.; Reese, R. S. NATO ASI Ser. 1996, 485, 143-162. (A85) Smalley, J. F.; Feldberg, S. W.; Newton, M. D.; Chidsey, C. E. D. Brookhaven Natl. Lab., [Rep.] BNL 1995, BNL 61733, Proceedings of the Nineteenth DOE Solar Photochemistry Research Conference, 1995; pp 95-97. (A86) Ottova, A. L.; Ti Tien, H. Bioelectrochem. Bioenerg. 1997, 42, 141-152. (A87) Deronzier, A.; Moutet, J. Curr. Top. Electrochem. 1994, 3, 159-200. (A88) Roncali, J. Chem. Rev. 1997, 97, 173-205. (A89) Kazarinov, V. E.; Pisarevskaya, E. Y.; Ovsyannikova, E. V.; Levi, M. D.; Alpatova, N. M. Russ. J. Electrochem. (Transl. of Elektrokhimiya) 1995, 31, 879-885. (A90) Deronzier, A.; Moutet, J. Coord. Chem. Rev. 1996, 147, 339371. (A91) Audebert, P.; Hapiot, P. Synth. Met. 1995, 75, 95-102. (A92) MacDiarmid, A. G.; Zheng, W. MRS Bull. 1997, 22, 24-30. (A93) Atta, N. F.; Russell, G. C.; Wang, Z.; Akmal, N.; Rubinson, J. F.; Lunsford, S. K.; Karagozler, E.; Ataman, O. Y.; Zimmer, H.; et al. Turk. J. Chem. 1997, 21, 21-29. (A94) Sadik, O. A. Anal. Methods Instrum. 1995, 2, 293-301. (A95) Wallace, G. G. Chem. Aust. 1995, 62, 16-18. (A96) Durst, R. A.; Baumner, A. J.; Murray, R. W.; Buck, R. P.; Andrieux, C. P. Pure Appl. Chem. 1997, 69, 1317-1323. (A97) Ugo, P.; Moretto, L. M. Electroanalysis 1995, 7, 1105-1113. (A98) Bontempelli, G.; Comisso, N.; Toniolo, R.; Schiavon, G. Electroanalysis 1997, 9, 433-443. (A99) Harth, R.; Ozer, D.; Hayon, J.; Ydgar, R.; Bettelheim, A. Curr. Top. Electrochem. 1994, 3, 531-543. (A100) Mafe, S.; Ramirez, P. Acta Polym. 1997, 48, 234-250. (A101) Audebert, P. Curr. Top. Electrochem. 1994, 3, 459-477. (A102) Salmon, M.; Aguilar, M. M. Curr. Top. Electrochem. 1994, 3, 53-60. (A103) Lamy-Pitara, E.; Barbier, J. Appl. Catal. 1997, 149, 49-87. (A104) Walcarius, A. Electroanalysis 1996, 8, 971-986. (A105) Palecek, E. Electroanalysis 1996, 8, 7-14. (A106) Armstrong, F. A.; Heering, H. A.; Hirst, J. Chem. Soc. Rev. 1997, 26, 169-179. (A107) Bedioui, F.; Devynck, J.; Bied-Charreton, C. J. Mol. Catal. A: Chem. 1996, 113, 3-11. (A108) Bedioui, F.; Trevin, S.; Devynck, J. Electroanalysis 1996, 8, 1085-1091. (A109) Oyama, N.; Ohsaka, T. Prog. Polym. Sci. 1995, 20, 761-818. (A110) Inzelt, G. Electroanalysis 1995, 7, 895-903. (A111) Cox, J. A.; Tess, M. E.; Cummings, T. E. Rev. Anal. Chem. 1996, 15, 173-223.

(A112) Kissinger, P. T.; Yang, L.; Bott, A.; Falck, D.; Bruntlett, C. Proc.-Electrochem. Soc. 1996, 96-9, 350-356. (A113) Moeller, A.; Scholz, F. Fresenius’ J. Anal. Chem. 1996, 356, 160-168. (A114) Buchberger, W. Fresenius’ J. Anal. Chem. 1996, 354, 797802. (A115) Budnikov, G. K. J. Anal. Chem. (Transl. of Zh. Anal. Khim.) 1996, 51, 143-148. (A116) Acworth, I. N.; Bowers, M. Prog. HPLC-HPCE 1997, 6, 3-50. (A117) Chen, J.; Woltman, S. J.; Weber, S. G. Adv. Chromatogr. (N.Y.) 1996, 36, 273-313. (A118) O’Shea, T. J. Prog. Pharm. Biomed. Anal. 1996, 2, 277-306. (A119) Kissinger, P. T. J. Pharm. Biomed. Anal. 1996, 14, 871-880. (A120) Kauffmann, J.; Pekli-Novak, M.; Nagy, A. Acta Pharm. Hung. 1996, 66, 57-64. (A121) Vire, J.-C.; Kauffmann, J.-M. Curr. Top. Electrochem. 1994, 3, 493-515. (A122) Wring, S. A.; Ayres, D.; Dayal, S.; Harrison, G. Methodol. Surv. Bioanal. Drugs 1996, 24, 262-274. (A123) Davies, M. J.; Hounsell, E. F. Biomed. Chromatogr. 1996, 10, 285-289. (A124) Fogg, A. G. Anal. Proc. 1995, 32, 433-435. (A125) Mocak, J.; Bond, A. M.; Mitchell, S.; Scollary, G. Pure Appl. Chem. 1997, 69, 297-328. (A126) Scarponi, G.; Capodaglio, G.; Barbante, C.; Cescon, P. Chem. Anal. (N.Y.) 1996, 135, 363-418. (A127) Bott, A. Curr. Sep. 1995, 14, 24-30. (A128) Kheifets, L. Y.; Vasyukov, A. E. J. Anal. Chem. (Transl. of Zh. Anal. Khim.) 1996, 51, 432-441. (A129) Mader, P.; Szakova, J.; Curdova, E. Talanta 1996, 43, 521534. (A130) Qu, Y. B. Analyst (Cambridge) 1996, 121, 139-161. (A131) Tur’yan, Y. I. Talanta 1997, 44, 1-13. (A132) Zhou, F. Electroanalysis 1996, 8, 855-861. (A133) Fogg, A. G. Port. Electrochim. Acta 1995, 13, 219-226. (A134) Economou, A.; Fielden, P. R. TrAC, Trends Anal. Chem. 1997, 16, 286-292. (A135) Urquidi-Macdonald, M.; Egan, P. C. Corros. Rev. 1997, 15, 169-194. (A136) Amirudin, A.; Thierry, D. Prog. Org. Coat. 1995, 26, 1-28. (A137) Swarup, J.; Sharma, P. C. Bull. Electrochem. 1996, 12, 103108. (A138) Gomes, W. P.; Vanmaekelbergh, D. Electrochim. Acta 1996, 41, 967-973. (A139) Dawson, J. L. ASTM Spec. Technol. Publ. 1996, STP 1277, 3-35. (A140) Koper, M. T. M. Adv. Chem. Phys. 1996, 92, 161-298. (A141) Molina, A. Curr. Top. Electrochem. 1994, 3, 201-220. (A142) Kirchhoff, J. R. Curr. Sep. 1997, 16, 11-14. (A143) Niu, J.; Dong, S. Rev. Anal. Chem. 1996, 15, 1-171. (A144) Niwa, O. Electroanalysis 1995, 7, 606-613. (A145) Bott, A. W. Curr. Sep. 1997, 16, 23-26. (A146) Bott, A. W. Curr. Sep. 1997, 16, 61-66. (A147) Bott, A. W. Curr. Sep. 1997, 14, 104-109. (A148) Falck, D. Curr. Sep. 1997, 16, 19-22. (A149) Duda, C. T.; Bruntlett, C. S. In Handbook of Instrumental Techniques for Analytical Chemistry; Settle, F. A., Ed.; Prentice Hall: Upper Saddle River, NJ, 1997; pp 691-708. (A150) Denauault, G. Chem. Ind. (London) 1996, 18, 678-680. (A151) Hill, H. A. Ann. Chim. (Rome) 1997, 87, 139-143. (A152) Walton, D. J.; Phull, S. S. Adv. Sonochem. 1996, 4, 205-284. (A153) Compton, R. G.; Eklund, J. C.; Marken, F. Electroanalysis 1997, 9, 509-522. (A154) Compton, R. G.; Eklund, J. C.; Marken, F.; Rebbitt, T. O.; Akkermans, R. P.; Waller, D. N. Electrochim. Acta 1997, 42, 2919-2927. (A155) Cousino, M. A.; Heineman, W. R.; Halsall, H. B. Ann. Chim. (Rome) 1997, 87, 93-101. (A156) O’Daly, J. P.; Henkens, R. W. Rev. Pestic. Toxicol. 1995, 3, 45-60. (A157) Lee, W. Y. Mikrochim. Acta 1997, 127, 19-39. (A158) Knight, A. W.; Greenway, G. M. Analyst (Cambridge) 1996, 121, 101R-106R. (A159) Novotny, L.; Heyrovsky, M. Croat. Chem. Acta 1997, 70, 151165. (A160) Stojanovic, R. S.; Greenhill, H. B.; Bond, A. M.; Anderson, J. E. Comput. Chem. 1996, 20, 209-218. (A161) Mogi, I. Physica B (Amsterdam) 1996, 216, 396-398. (A162) Willig, F.; Schwarzburg, K.; Troesken, B.; Mahrt, J.; Motte, L.; Pileni, M.-P. NATO ASI Ser. 1996, 12, 591-608. (A163) Henglein, A. Ber. Bunsen-Ges. 1995, 99, 903-913. (A164) Heyrovsky, M.; Jirkovsky, J. NATO ASI Ser. 1996, 18, 161166. (A165) Boulas, P. L.; Echegoyen, L. Electrochem. Soc. Interface 1997, 6, 36-41. (A166) Xu, J.; Granger, M. C.; Chen, Q.; Strojek, J. W.; Lister, T. E.; Swain, G. M. Anal. Chem. 1997, 69, 591A-597A. (A167) Alber, K. S.; Cox, J. A.; Kulesza, P. J. Electroanalysis 1997, 9, 97-101. (A168) Trasatti, S. Int. J. Hydrogen Energy 1995, 20, 835-844. (A169) Simonsson, D. Chem. Soc. Rev. 1997, 26, 181-189. (A170) Bersier, P. M.; Carlsson, L.; Bersier, J. Top. Curr. Chem. 1994, 170, 113-229.

(A171) (A172) (A173) (A174) (A175) (A176) (A177) (A178) (A179) (A180) (A181) (A182) (A183) (A184) (A185) (A186) (A187) (A188) (A189) (A190) (A191) (A192) (A193) (A194) (A195) (A196) (A197) (A198) (A199) (A200) (A201) (A202) (A203) (A204)

(A205) (A206) (A207) (A208) (A209) (A210) (A211) (A212) (A213) (A214) (A215) (A216) (A217) (A218) (A219) (A220) (A221)

Thomas, J. D. R. Sci. Technol. Environ. Prot. 1995, 2, 1-8. Lewis, N. S. Electrochem. Soc. Interface 1996, 5, 28-31. Mraci, D. M. Chem. Aust. 1995, 62, 8-9. Rajeshwar, K. J. Appl. Electrochem. 1995, 25, 1067-1082. Stamford, J. A.; Palij, P.; Davidson, C.; Trout, S. J. Bioelectrochem. Bioenerg. 1995, 38, 289-296. Justice, J. B., Jr.; Bailey, M. D.; Barker, E. L.; Blakely, R. D. NATO ASI Ser. 1997, 100, 249-261. Stamford, J. A.; Justice, J. B., Jr. Anal. Chem. 1996, 68, 359A363A. Gonon, F. Bioelectrochem. Bioenerg. 1995, 38, 247-249. Angelson, J. K.; Betz, W. J. Trends Neurosci. 1997, 20, 281287. Blaha, C. D.; Phillips, A. G. Behav. Pharmacol. 1996, 7, 675708. Mas, M.; Fumero, B.; Gonzalez-Mora, J. L. Behav. Brain Res. 1995, 71, 69-79. Mas, M.; Gonzalez-Mora, J. L.; Hernandez, L. Cell. Mol. Neurobiol. 1996, 16, 383-396. Neher, E.; Chow, R. H. Bioelectrochem. Bioenerg. 1995, 38, 251-253. Palanti, S.; Marrazza, G.; Mascini, M. Anal. Lett. 1996, 29, 2309-2331. Johnston, D. H.; Welch, T. W.; Thorp, H. H. Met. Ions Biol. Syst. 1996, 33, 297-324. Estabrook, R. W.; Faulkner, K. M.; Shet, M. S.; Fisher, C. W. Methods Enzymol. 1996, 272 (Part B), 44-51. Hong, F. T. Mater. Sci. Eng. 1997, C4, 267-285. Ruzgas, T.; Csoeregi, E.; Emmneus, J.; Gorton, L.; MarkoVarga, G. Anal. Chim. Acta 1996, 330, 123-138. Lu, B.; Smyth, M. R.; O’Kennedy, R. Analyst (Cambridge) 1996, 121, 29R-32R. Freitag, R. Biosensors in Analytical Biotechnology; Academic: San Diego, 1996; pp 99-127. De Oliveira, P.; Hill, H. A. In Handbook of Metal-Ligand Interactions Biological Fluids: Bioinorganic Chemistry; Berthon, G., Ed.; Dekker: New York, 1995; Vol. 1, pp 324-338. Santucci, R.; Picciau, A.; Campanella, L.; Brunori, M. Curr. Top. Electrochem. 1994, 3, 313-328. Borsari, M.; Battistuzzi, G.; Sola, M. Trends Inorg. Chem. 1996, 4, 1-8. Hill, H. A.; Guo, L. H.; McLendon, G. In Cytochrome C. A Multidisciplinary Approach; Scott, R. A., Mauk, A. G., Eds.; University Science Books: Sausalito, CA, 1996; pp 317-333. Ikeda, T. EXS 1997, 80, 243-266. Ghindilis, A. L.; Atanasov, P.; Wilkins, E. Electroanalysis 1997, 9, 661-674. Katakis, I.; Vreeke, M.; Ye, L.; Aoki, A.; Heller, A. Adv. Mol. Cell Biol. 1996, 15B, 391-409. Katakis, I.; Heller, A. EXS 1997, 80, 229-241. Pishko, M. Trends Polym. Sci. (Cambridge, U.K.) 1995, 3, 342-7. Senda, M. EXS 1997, 80, 193-207. Somers, W. A. C.; Van Hartingsveldt, W.; Stigter, E. C. A.; Van Der Lugt, J. P. Agro-Food-Ind. Hi-Tech. 1997, 8, 32-35. Steckhan, E.; Brielbeck, B.; Frede, M.; Hilt, G. Int. Forum Electrolysis Chem. Ind. 1996, 10, 226-254. Bourdillon, C.; Demaille, C.; Moiroux, J.; Save´ant, J.-M. Acc. Chem. Res. 1996, 29, 529-535. Anderson, D. J.; Guo, B.; Xu, Y.; Ng, L. M.; Kricka, L. J.; Skogerboe, K. J.; Hage, D. S.; Schoeff, L.; Wang, J.; Sokoll, L. J.; Chan, D. W.; Ward, K. M.; Davis, K. A. Anal. Chem. 1997, 69, 165R-229R. Trojanowicz, M.; Hitchman, M. TrAC, Trends Anal. Chem. 1996, 15, 38-45. Chemnitius, G.; Meusel, M.; Zaborosch, C.; Knoll, M.; Spener, F.; Cammann, K. Food Technol. Biotechnol. 1996, 34, 23-29. Bassi, A. S.; Tang, D.; Lee, E.; Zhu, J. X.; Bergougnou, M. A. Food Technol. Biotechnol. 1996, 34, 9-22. Wang, J. TrAC, Trends Anal. Chem. 1997, 16, 84-88. Rogers, K. R.; Gerlach, C. L. Environ. Sci. Technol. 1996, 30, 486A-491A. Morgan, C. L.; Newman, D. J.; Price, C. P. Clin. Chem. (Washington, D.C.) 1996, 42, 193-209. Yang, M.; McGovern, M. E.; Thompson, M. Anal. Chim. Acta 1997, 346, 259-275. Emr, S. A.; Yacynych, A. M. Electroanalysis 1995, 7, 913923. Adeloju, S. B.; Wallace, G. G. Analyst (Cambridge) 1996, 121, 699-703. Gorton, L.; Marko-Varga, G.; Persson, B.; Huan, Z.; Linden, H.; Burestedt, E.; Ghobadi, S.; Smolander, M.; Sahni, S.; Skotheim, T. Adv. Mol. Cell Biol. 1996, 15B, 421-450. Barreau, S.; Miller, J. N. Anal. Commun. 1996, 33, 5H-6H. Varfolomeev, S. D.; Kurochkin, I. N.; Yaropolov, A. I. Biosens. Bioelectron. 1996, 11, 863-871. Bousse, L. Sens. Actuators 1996, B34, 270-275. Schuegerl, K.; Ulber, R.; Scheper, T. TrAC, Trends Anal. Chem. 1996, 15, 56-62. Harwood: G. W. J.; Pouton, C. W. Adv. Drug Delivery Rev. 1996, 18, 163-191. Matthews, D. J. Annu. Rep. Med. Chem. 1995, 30, 275-283. Pfeiffer, D. EXS 1997, 81, 149-160.

Analytical Chemistry, Vol. 70, No. 12, June 15, 1998

575R

(A222) Gough, D. A.; Armour, J. C.; Baker, D. A. Diabetologia 1997, 40, S102-S107. (A223) Ballerstadt, R.; Schultz, J. S. Adv. Drug Delivery Rev. 1996, 21, 225-237. (A224) Luong, J. H. T.; Bouvrette, P.; Male, K. B. Trends Biotechnol. 1997, 15, 369-377. (A225) Iwuoha, E. I.; Smyth, M. R. Biosens. Bioelectron. 1996, 12, 53-75. MASS TRANSPORT (B1) The Electrochemical Science and Technology Information Resource. http://electrochem.cwru.edu/estir/. (B2) The Compton Group. Chemistry at the solid-liquid interface; Alden, J. A. site manager. http://physchem.ox.ac.uk:8000/ frame.shtml. (B3) Fang, H.; Chen, H.-Y. Chin. J. Chem. 1997, 15, 250-259. (B4) Alden, J. A.; Compton, R. G.; Dryfe, R. A. W. J. Appl. Electrochem. 1996, 26, 865-872. (B5) Alden, J. A.; Compton, R. G. J. Electroanal. Chem. 1996, 402, 1-10. (B6) Alden, J. A.; Hutchinson, F.; Compton, R. G. J. Phys. Chem. B 1997, 101, 949-958. (B7) Alden, J. A.; Compton, R. G. J. Phys. Chem. B 1997, 101, 89418954. (B8) Alden, J. A.; Compton, R. G. J. Phys. Chem. B 1997, 101, 96069616. (B9) Alden, J. A.; Compton, R. G. J. Phys. Chem. B 1997, 101, 97419750. (B10) Alden, J. A.; Compton, R. G. J. Electroanal. Chem. 1996, 415, 1-12. (B11) Gavaghan, D. J. J. Electroanal. Chem. 1997, 420, 147-158. (B12) Bieniasz, L. K.; Osterby, O.; Britz, D. Comput. Chem. 1995, 19, 351-355. (B13) Bieniasz, L. K.; Osterby, O.; Britz, D. Comput. Chem. 1995, 19, 357-370. (B14) Feldberg, S. W.; Goldstein, C. I.; Rudolph, M. J. Electroanal. Chem. 1996, 413, 25-36. (B15) Bott, A. W. Curr. Sep. 1996, 14, 104-109. (B16) Garcia-Hernandez, M. T.; Castilla, J.; Gonzalez-Fernandez, C. F.; Horno, J. J. Electroanal. Chem. 1997, 424, 207-212. (B17) Horno, J.; Garcia-Hernandez, M. T.; Castilla, J.; GonzalezFernandez, C. F. Electroanalysis 1996, 8, 1145-1149. (B18) Jin, B.; Qian, W.; Zhang, Z.; Shi, H. J. Electroanal. Chem. 1996, 411, 19-27. (B19) Stevens, N. P. C.; Hickey, S. J.; Fisher, A. C. An. Quim. Int. Ed. 1997, 93, 225-232. (B20) Gosser, D. K., Jr. Chem. Anal. (N.Y.) 1996, 139 (Modern Techniques in Electroanalysis), 313-335. (B21) Speiser, B. Electroanal. Chem. 1996, 19, 1-108. (B22) Geshev, P. I. J. Electroanal. Chem. 1996, 410, 1-8. (B23) Cope, D. K.; Tallman, D. E. J. Electroanal. Chem. 1995, 396, 265-275. (B24) Engblom, S. O.; Cope, D. K.; Tallman, D. E. J. Electroanal. Chem. 1996, 406, 23-31. (B25) Cope, D. K. Anal. Chem. 1997, 69, 1465-1469. (B26) Slevin, C. J.; Macpherson, J. V.; Unwin, P. R. J. Phys. Chem. B 1997, 101, 10851-10859. (B27) Martin, R. D.; Unwin, P. R. Anal. Chem. 1998, 70, 276-284. (B28) Macpherson, J. V.; Unwin, P. R. J. Phys. Chem. 1996, 100, 19475-19483. (B29) Demaille, C.; Unwin, P. R.; Bard, A. J. J. Phys. Chem. 1996, 100, 14137-14143. (B30) Klusman, E.; Schultze, J. W. Electrochim. Acta 1997, 42, 3123-3134. (B31) Stevens, N. P. C.; Fisher, A. C. J. Phys. Chem. B 1997, 101, 8259-8263. (B32) Aixill, W. J.; Fisher, A. C.; Fulian, Q. J. Phys. Chem. 1996, 100, 14067-14073. (B33) Ferrigno, R.; Brevet, P.-F.; Girault, H. H. J. Electroanal. Chem. 1997, 430, 235-242. (B34) Ferrigno, R.; Brevet, P. F.; Girault, H. H. Electrochim. Acta 1997, 42, 1895-1903. (B35) Lee, C.-W.; Eklund, J. C.; Dryfe, R. A. W.; Compton, R. G. Bull. Korean Chem. Soc. 1996, 17, 162-167. (B36) Alden, J. A.; Cooper, J. A.; Hutchinson, F.; Prieto, F.; Compton, R. G. J. Electroanal. Chem. 1997, 432, 63-70. (B37) Bidwell, M. J.; Alden, J. A.; Compton, R. G. J. Electroanal. Chem. 1996, 417, 119-128. (B38) Leslie, W. M.; Alden, J. A.; Compton, R. G.; Silk, T. J. Phys. Chem. 1996, 100, 14130-14136. (B39) Leslie, W. M.; Compton, R. G.; Silk, T. Electrochim. Acta 1997, 42, 3575-3584. (B40) Jin, B.; Qian, W.; Zhang, Z.; Shi, H. J. Electroanal. Chem. 1996, 417, 45-51. (B41) Phillips, C. G.; Stone, H. A. J. Electroanal. Chem. 1995, 396, 277-284. (B42) Antonello, S.; Maran, F. J. Am. Chem. Soc. 1997, 119, 1259512600. (B43) Alden, J. A.; Compton, R. G.; Dryfe, R. A. W. J. Electroanal. Chem. 1995, 397, 11-17. (B44) Diao, G.; Zhang, Z. J. Electroanal. Chem. 1997, 429, 67-74. 576R

Analytical Chemistry, Vol. 70, No. 12, June 15, 1998

(B45) Diao, G.; Zhang, Z. J. Electroanal. Chem. 1996, 410, 155162. (B46) Diao, G.-W.; Li, L.; Zhang, Z.-X. Chin. J. Chem. 1996, 14, 331337. (B47) Qian, W.; Jin, B.; Diao, G.; Zhang, Z.; Shi, H. J. Electroanal. Chem. 1996, 414, 1-10. (B48) Alfred, L. C. R.; Oldham, K. B. J. Phys. Chem. 1996, 100, 21702177. (B49) Oldham, K. B. Proc.-Electrochem. Soc. 1996, 96-9 (New Directions in Electroanalytical Chemistry), 12-25. (B50) Oldham, K. B. J. Electroanal. Chem. 1997, 420, 53-61. (B51) Sokirko, A. V.; Oldham, K. B. J. Electroanal. Chem. 1997, 430, 15-24. (B52) Jin, B.-K.; Zhang, J.-R.; Zhang, Z.-X. Chin. J. Chem. 1996, 14, 338-347. (B53) Fisher, A. C.; Davies, C. W.; Fulian, Q.; Walters, M. Electroanalysis 1997, 9, 849-856. (B54) Cassidy, J.; Mullen, D.; Casey, K.; Cullen, P. Electroanalysis 1996, 8, 918-921. (B55) Jin, W.; Chen, H. J. Chromatogr., A 1997, 765, 307-314. (B56) Ball, J. C.; Compton, R. G. Electroanalysis 1997, 9, 765-769. (B57) Schiewe, J.; Oldham, K. B.; Myland, J. C.; Bond, A. M.; VicenteBeckett, V. A.; Fletcher, S. Anal. Chem. 1997, 69, 2673-2681. (B58) Kamenev, A. I.; Rumyantsev, A. Y.; Shushakov, P. A. J. Anal. Chem. (Transl. of Zh. Anal. Khim.) 1997, 52, 827-830. (B59) Garai, T.; Nagy, Z.; Bartalits, L.; Meszaros, L.; Fagioli, F.; Locatelli, C. Magy. Kem. Foly. 1997, 103, 51-60. (B60) Honeychurch, M. J.; Ridd, M. J. Electroanalysis 1995, 7, 10411047. (B61) Bi, S.; Yu, J. J. Electroanal. Chem. 1996, 405, 51-58. (B62) Pizeta, I.; Branica, M. Anal. Chim. Acta 1997, 351, 73-82. (B63) van den Hoop, M. A. G. T.; Benegas, J. C.; van Leeuwen, H. P. Anal. Chim. Acta 1995, 317, 327-334. (B64) Galvez, J. J. Electroanal. Chem. 1996, 413, 15-23. (B65) Molina, A.; Martinez-Ortiz, F.; Serna, C.; Camacho, L.; Ruiz, J. J. J. Electroanal. Chem. 1996, 408, 33-45. (B66) Berbel, F.; Manuel Diaz-Cruz, J.; Arino, C.; Esteban, M. J. Electroanal. Chem. 1997, 431, 99-110. (B67) Xie, Y.; Kang, C.; Anson, F. C. J. Chem. Soc., Faraday Trans. 1996, 92, 3917-3923. (B68) Lovric, M.; Komorsky-Lovric, S.; Scholz, F. Electroanalysis 1997, 9, 575-577. (B69) Yu, J.-S.; Zhang, Z.-X. J. Electroanal. Chem. 1997, 427, 7-14. (B70) Galvez, J. J. Electroanal. Chem. 1996, 401, 21-32. (B71) Speiser, B. J. Electroanal. Chem. 1996, 413, 67-79. (B72) Moharram, Y. I. Monatsh. Chem. 1997, 128, 1207-1217. (B73) Ramanathan, K.; Mehrotra, R.; Jayaram, B.; Murthy, A. S. N.; Malhotra, B. D. Anal. Lett. 1996, 29, 1477-1484. (B74) Cambiaso, A.; Delfino, L.; Grattarola, M.; Verreschi, G.; Ashworth, D.; Maines, A.; Vadgama, P. Sens. Actuators 1996, B33, 203-207. (B75) Sorochinskii, V. V.; Kurganov, B. I. Biosens. Bioelectron. 1996, 11, 709-718. (B76) Jobst, G.; Moser, I.; Urban, G. Biosens. Bioelectron. 1996, 11, 111-117. (B77) Ambari, A.; Tribollet, B.; Compere, C.; Festy, D.; L’hostis, E. Eur. Fed. Corros. Publ. 1995, 15 (BMicrobial Corrosion), 211222. (B78) Galceran, J.; Salvador, J.; Puy, J.; Cecilia, J.; Gavaghan, D. J. Analyst (Cambridge, U.K.) 1996, 121, 1863-1868. (B79) Sutton, L.; Gavaghan, D. J.; Hahn, C. E. W. J. Electroanal. Chem. 1996, 408, 21-31. (B80) Cassidy, J.; McCormac, T. Electroanalysis 1996, 8, 139-142. (B81) Wang, J.; Bell, J. M.; Skryabin, I. L. Proc. SPIE-Int. Soc. Opt. Eng. 1997, 3138 (Optical Materials Technology for Energy Efficiency and Solar Energy Conversion XV), 20-30. (B82) Morf, W. E. Anal. Chim. Acta 1997, 341, 121-127. (B83) Morf, W. E. Anal. Chim. Acta 1996, 330, 139-149. (B84) Cohen, R. R.; Radke, C. J. J. Electroanal. Chem. 1996, 405, 23-32. (B85) Jin, B.; Qian, W.; Zhang, Z.; Shi, H. J. Electroanal. Chem. 1996, 411, 29-36. (B86) Compton, R. G.; Gooding, J. J.; Sokirko, A. J. Appl. Electrochem. 1996, 26, 463-469. (B87) Tam, K. Y.; Larsen, J. P.; Coles, B. A.; Compton, R. G. J. Electroanal. Chem. 1996, 407, 23-35. (B88) Chen, J. S.; Diard, J.-P.; Durand, R.; Montella, C. J. Electroanal. Chem. 1996, 406, 1-13. (B89) Grafov, B. M.; Damaskin, B. B. Electrochim. Acta 1996, 41, 2707-2714. (B90) Martinusz, K.; Lang, G.; Inzelt, G. J. Electroanal. Chem. 1997, 433, 1-8. (B91) Blankenborg, S. G. J.; Sluyters-Rehbach, M.; Sluyters, J. H. J. Electroanal. Chem. 1996, 401, 3-19. (B92) Prieto, F.; Rueda, M.; Navarro, I.; Sluyters-Rehbach, M.; Sluyters, J. H. J. Electroanal. Chem. 1996, 405, 1-14. (B93) Koper, M. T. M. J. Electroanal. Chem. 1996, 409, 175-182. (B94) Calvente, J.-J.; Kovacova, Z.; Andreu, R.; Fawcett, W. R. J. Chem. Soc., Faraday Trans. 1996, 92, 3701-3708. (B95) Meunier-Prest, R.; Laviron, E. J. Electroanal. Chem. 1996, 410, 133-143. (B96) Georgiadou, M. J. Electrochem. Soc. 1997, 144, 2732-2739.

(B97) Bortels, L.; Deconinck, J.; Van Den Bossche, B. J. Electroanal. Chem. 1996, 404, 15-26. (B98) Oldham, K. B.; Cardwell, T. J.; Santos, J. H.; Bond, A. M. J. Electroanal. Chem. 1997, 430, 25-37. (B99) Oldham, K. B.; Cardwell, T. J.; Santos, J. H.; Bond, A. M. J. Electroanal. Chem. 1997, 430, 39-46. (B100) Oldham, K. B. Anal. Chem. 1996, 68, 4173-4179. (B101) Jaworski, A.; Donten, M.; Stojek, Z.; Osteryoung, J. G. Proc.Electrochem. Soc. 1997, 97-19 (Chemical and Biological Sensors and Analytical Electrochemical Methods), 481-484. (B102) Hyk, W.; Stojek, Z. Proc.-Electrochem. Soc. 1997, 97-19 (Chemical and Biological Sensors and Analytical Electrochemical Methods), 444-450. (B103) Hyk, W.; Palys, M.; Stojek, Z. J. Electroanal. Chem. 1996, 415, 13-22. (B104) Hyk, W.; Stojek, Z. J. Electroanal. Chem. 1997, 422, 179184. (B105) Strutwolf, J.; Schoeller, W. W. Electroanalysis 1996, 8, 10341039. (B106) Garcia-Jareno, J. J.; Navarro-Laboulais, J.; Vicente, F. Electrochim. Acta 1997, 42, 1473-1480. (B107) Coles, B. A.; Compton, R. G.; Larsen, J. P.; Spackman, R. A. Electroanalysis 1996, 8, 913-917. (B108) Yamada, K.; Kitamura, F.; Ohsaka, T.; Tokuda, K. J. Electrochem. Soc. 1996, 143, 4006-4012. (B109) Vazquez, L.; Salvarezza, R. C.; Arvia, A. J. Phys. Rev. Lett. 1997, 79, 709-712. (B110) Salvarezza, R. C.; Arvia, A. J. ACH-Models Chem. 1997, 134, 113-128. (B111) Tadano, A.; Aogaki, R. J. Chem. Phys. 1997, 106, 6126-6137. (B112) Tadano, A.; Aogaki, R. J. Chem. Phys. 1997, 106, 6146-6151. (B113) Nagy, G.; Sugimoto, Y.; Denuault, G. J. Electroanal. Chem. 1997, 433, 167-173. (B114) Nagy, G.; Denuault, G. J. Electroanal. Chem. 1997, 433, 175180. (B115) Huang, W.; Hibbert, D. B. Physica B (Amsterdam) 1996, 233 (B3-4, Pattern Formation, Fractals and Statistical Mechanics), 888-896. (B116) Harrington, D. A. J. Electroanal. Chem. 1997, 420, 101-109. (B117) Dezhkunov, N. V.; Kulak, A. I.; Francescutto, A. Ultrasonics 1996, 34, 551-553. (B118) Yamaguchi, F.; Huang, D.; Yamamoto, Y. Jpn. J. Appl. Phys. 1997, 36 (Part 1), 3799-3803. (B119) Green, N. G.; Morgan, H. J. Phys. D: Appl. Phys. 1997, 30, 2626-2633. (B120) Saltykov, Y. V.; Kornienko, V. L. Russ. J. Electrochem. (Transl. of Elektrokhimiya) 1996, 32, 1172-1174. (B121) Engelhardt, G. R.; Lvov, S. N.; Macdonald, D. D. J. Electroanal. Chem. 1997, 429, 193-201. ANALYTICAL VOLTAMMETRY (C1) Bund, A.; Dittmann, J.; Lordkipanidze, D.; Schwitzgebel, G. Fresenius’ J. Anal. Chem. 1996, 356, 27-30. (C2) Conte, E. D.; Miller, D. W. J. High Resolut. Chromatogr. 1996, 19, 294-297. (C3) Blum, D.; Leyffer, W.; Holze, R. Electroanalysis 1996, 8, 296297. (C4) Morita, M.; Niwa, O.; Horiuchi, T. Electrochim. Acta 1997, 42, 3177-3183. (C5) Kauffmann, J.-M.; Pekli-Novak, M.; Nagy, A. Acta Pharm. Hung. 1996, 66, 57-64. (C6) Trojanowicz, M.; Hitchman, M. TrAC, Trends Anal. Chem. 1996, 15, 38-45. (C7) Qu, Y. B. Analyst (Cambridge, U.K.) 1996, 121, 139-161. (C8) Walcarius, A. Electroanalysis 1996, 8, 971-986. (C9) Hietpas, P. B.; Gilman, S. D.; Lee, R. A.; Wood, M. R.; Winograd, N.; Ewing, A. G. In Nanofabrication and Biosystems; Hoch, H. C., Jelinski, L. W., Craighead, H. G., Eds.; Cambridge University Press: Cambridge, U.K., 1996; pp 139-158. (C10) Clark, R. A.; Ewing, A. G. Mol. Neurobiol. 1997, 15, 1-16. (C11) Budnikov, G. K. J. Anal. Chem. (Transl. of Zh. Anal. Khim.) 1996, 51, 143-148. (C12) Kissinger, P. T. J. Pharm. Biomed. Anal. 1996, 14, 871-880. (C13) Chen, J.-G.; Woltman, S. J.; Weber, S. G. Adv. Chromatogr. (N.Y). 1996, 36, 273-313. (C14) Davies, M. J.; Hounsell, E. F. Biomed. Chromatogr. 1996, 10, 285-289. (C15) Takata, Y. Methods Chromatogr. 1996, 1 (Advances in Liquid Chromatography), 43-74. (C16) Acworth, I. N.; Bowers, M. Prog. HPLC-HPCE 1997, 6 (Coulometric Electrode Array Detectors for HPLC), 3-50. (C17) Cullison, J. K.; Gamache, P. H. Prog. HPLC-HPCE 1997, 6 (Coulometric Electrode Array Detectors for HPLC), 51-74. (C18) Sontag, G.; Bernwieser, I.; Krach, C. Prog. HPLC-HPCE 1997, 6 (Coulometric Electrode Array Detectors for HPLC), 75-98. (C19) Deleted in proof. (C20) Largeaud, F.; Kokoh, K. B.; Beden, B.; Lamy, C. J. Electroanal. Chem. 1995, 397, 261-269. (C21) Yu, J. J.; Huang, W.; Hibbert, B. Electroanalysis 1997, 9, 544548.

(C22) Vogt, M.; Shoemaker, E.; Turner, T. Sens. Actuators 1996, B36, 370-376. (C23) Paras, C. D.; Kennedy, R. T. Electroanalysis 1997, 9, 203208. (C24) Hsueh, ChenC.; Bravo, R.; Jaramillo, A. J.; Brajter-Toth, A. Anal. Chim. Acta 1997, 349, 67-76. (C25) Dressman, S. F.; Simeone, A. M.; Michael, A. C. Anal. Chem. 1996, 68, 3121-3127. (C26) Parker, V. D.; Seefeldt, L. C. Anal. Biochem. 1997, 247, 152157. (C27) Takamura, K.; Fuse, T.; Kusu, F. J. Electroanal. Chem. 1995, 396, 507-510. (C28) Cullison, J. K.; Kuhr, W. G. Electroanalysis 1996, 8, 314-319. (C29) Tess, M. E.; Cox, J. A. Anal. Chem. 1998, 70, 187-190. (C30) Singhal, P.; Kawagoe, K. T.; Christian, C. N.; Kuhr, W. G. Anal. Chem. 1997, 69, 1662-1668. (C31) Singhal, P.; Kuhr, W. G. Anal. Chem. 1997, 69, 3552-3557. (C32) Vas, C. M. P.; Crestana, S.; Machado, S. A. S.; Mazo, L. H.; Avaca, L. A. Electroanalysis 1997, 9, 956-958. (C33) Berzas, J. J.; Rodriguez, J.; Castaneda, G. Anal. Chim. Acta 1997, 349, 303-311. (C34) Fang, H.; Chen, H.-y. Anal. Chim. Acta 1997, 346, 319-325. (C35) Hoekstra, J. C.; Johnson, D. C. Anal. Chem. 1998, 70, 8388. (C36) Elliott, P. T.; Olsen, S. A.; Tallman, D. E. Electroanalysis 1996, 8, 443-446. (C37) Weitzhandler, M.; Pohl, C.; Rohrer, J.; Narayanan, L.; Slingsby, R.; Avdalovic, N. Anal. Biochem. 1996, 241, 128-134. (C38) Roberts, R. E.; Johnson, D. C. Electroanalysis 1995, 7, 10151019. (C39) Dobberpuhl, D. A.; Hoekstra, J. C.; Johnson, D. C. Anal. Chim. Acta 1996, 322, 55-62. (C40) Doscotch, M. A.; Jones, J. A.; Welch, L. E. Anal. Chim. Acta 1997, 344, 55-64. (C41) Fung, Y.; Mo, S. Analyst (Cambridge, U.K.) 1996, 121, 369372. (C42) Chen, G. N.; Lin, R. E.; Zhao, Z. F.; Duan, J. P.; Zhang, L. Anal. Chim. Acta 1997, 341, 251-256. (C43) Armalis, S.; Pockeviciute, D.; Tatolyte, O. Fresenius’ J. Anal. Chem. 1996, 354, 696-698. (C44) Armalis, S.; Johansson, G. Anal. Chim. Acta 1997, 339, 155159. (C45) Lukaszewski, Z.; Zembrzuski, W.; Piela, A. Anal. Chim. Acta 1996, 318, 159-165. (C46) Sundd, S.; Prasad, B. B. Talanta 1995, 42, 1395-1409. (C47) Mikac, N.; Wang, Y.; Harrison, R. M. Anal. Chim. Acta 1996, 326, 57-66. (C48) Ivaska, A.; Kubiak, W. W. Talanta 1997, 44, 713-723. (C49) Zhou, F.; Aronson, J. T.; Ruegnitz, M. W. Anal. Chem. 1997, 69, 728-733. (C50) Belmont, C.; Tercier, M.-L.; Buffle, J.; Fiaccabrino, G. C.; Koudelka-Hep, M. Anal. Chim. Acta 1996, 329, 203-214. (C51) Lam, M. T.; Chakrabarti, C. L.; Cheng, J.; Pavski, V. Electroanalysis 1997, 9, 1018-1029. (C52) Zhou, M.; Myung, N.; Rajeshwar, K. Electroanalysis 1996, 8, 1140-1144. (C53) Brand, M.; Eshkenazi, I.; Kirowa-Eisner, E. Anal. Chem. 1997, 69, 4660-4664. (C54) Herdan, J.; Feeney, R.; Kounaves, S. P.; Flannery, A. F.; Storment, C. W.; Kovacs, G. T. A.; Darling, R. B. Environ. Sci. Technol. 1998, 32, 131-136. (C55) Reay, R. J.; Flannery, A. F.; Storment, C. W.; Kouvanes, S. P.; Kovacs, G. T. A. Sens. Actuators 1996, B34, 450-455. (C56) Brett, C. M. A.; Oliveira Brett, A. M.; Tugulea, L. Anal. Chim. Acta 1996, 322, 151-157. (C57) de Betono, S. F.; Moreda, J. M.; Arranz, A.; Arranz, J. F. Anal. Chim. Acta 1996, 329, 25-31. (C58) Daniel, A.; Baker, A. R.; Van den Berg, C. M. G. Fresenius’ J. Anal. Chem. 1997, 358, 703-710. (C59) Sander, S.; Wagner, W.; Henze, G. Anal. Chim. Acta 1997, 349, 93-99. (C60) Brett, C. M. A.; Garcia, M. B. Q.; Lima, J. L. F. C. Electroanalysis 1996, 8, 1169-1173. (C61) Rocha, M. M. G. S.; Neto, M. M. P. M.; Torres, M. O.; De Varennes, A. Electroanalysis 1997, 9, 145-149. (C62) Brett, C. M. A.; Brett, A. M. O.; Matysik, F.-M.; Matysik, S. Proc. - Electrochem. Soc. 1997, 97-19 (Chemical and Biological Sensors and Analytical Electrochemical Methods), 149154. (C63) Brett, C. M. A.; Brett, A. M. O.; Tugulea, L. Electroanalysis 1996, 8, 639-642. (C64) Morais, S.; Carvalho, G. S.; Sousa, J. P. Electroanalysis 1997, 9, 422-426. (C65) Zanoni, M. V. B.; Fogg, A. G.; Barek, J.; Zima, J. Anal. Chim. Acta 1997, 349, 101-109. (C66) Ishiyama, T.; Tanaka, T. Anal. Chem. 1996, 68, 3789-3792. (C67) Roitz, J. S.; Bruland, K. W. Anal. Chim. Acta 1997, 344, 175180. (C68) Al-Farawati, R.; van den Berg, C. M. G. Mar. Chem. 1997, 57, 277-286. (C69) Zen, J.-M.; Jeng, S.-H.; Chen, H.-J. Anal. Chem. 1996, 68, 498502.

Analytical Chemistry, Vol. 70, No. 12, June 15, 1998

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(C70) Kakizaki, T.; Hasebe, K. Fresenius’ J. Anal. Chem. 1998, 360, 175-178. (C71) Riso, R. D.; Monbet, P.; Corre, P. L. Analyst (Cambridge, U.K.) 1997, 122, 1593-1596. (C72) Hwang, T.-J.; Jiang, S.-J. J. Anal. At. Spectrom. 1996, 11, 353357. (C73) Zhou, F.; Van Berkel, G. J.; Morton, S. J.; Duckworth, D. C.; Adeniyi, W. K.; Keller, J. M. ASTM Spec. Technol. Publ. 1995, Stp 1291 (Applications of Inductively Coupled Plasma-Mass Spectrometry to Radionuclide Determinations), 82-98. (C74) Hissner, F.; Mattusch, J.; Werner, G. Fresenius’ J. Anal. Chem. 1996, 354, 718-721. (C75) Gorski, W.; Aspinwall, C. A.; Lakey, J. R. T.; Kennedy, R. T. J. Electroanal. Chem. 1997, 425, 191-199. (C76) Casella, I. G.; Guascito, M. R.; Salvi, A. M.; Desimoni, E. Anal. Chim. Acta 1997, 354, 333-341. (C77) Pamidi, P. V. A.; Wang, J. Electroanalysis 1996, 8, 244-247. (C78) Liu, J.; Zhou, W.; You, T.; Li, F.; Wang, E.; Dong, S. Anal. Chem. 1996, 68, 3350-3353. (C79) You, T.; Wu, M.; Wang, E. Anal. Lett. 1997, 30, 1025-1036. (C80) Jin, J. Y.; Takeuchi, T.; Miwa, T. Analusis 1997, 25, 207210. (C81) Luo, P. F.; Kuwana, T.; Paul, D. K.; Sherwood, P. M. A. Anal. Chem. 1996, 68, 3330-3337. (C82) Marioli, J. M.; Sereno, L. E. J. Liq. Chromatogr. Relat. Technol. 1996, 19, 2505-2515. (C83) Neuhold, C. G.; Kalcher, K.; Cai, X.; Raber, G. Anal. Lett. 1996, 29, 1685-1704. (C84) Fitsev, I. M.; Budnikov, G. K.; Anisimova, L. A.; Garifzyanov, A. R. J. Anal. Chem. (Transl. of Zh. Anal. Khim.) 1996, 51, 465-467. (C85) Walker, J. W.; Buttry, D. A. Proc.-Electrochem. Soc. 1996, 96-9 (New Directions in Electroanalytical Chemistry), 95-109. (C86) Zhao, S.; Luong, J. H. T. Anal. Chim. Acta 1996, 327, 235242. (C87) Niwa, O.; Horiuchi, T.; Morita, M.; Huang, T.; Kissinger, P. T. Anal. Chim. Acta 1996, 318, 167-173. (C88) Kasai, N.; Matsue, T.; Uchida, I.; Horiuchi, T.; Morita, M.; Niwa, O. Denki Kagaku oyobi Kogyo Butsuri Kagaku 1996, 64, 12691271. (C89) Jin, W. R.; Wei, H. Y.; Zhao, X. Electroanalysis 1997, 9, 770774. (C90) Jin, W.; Weng, Q.; Wu, J. Anal. Chim. Acta 1997, 342, 6774. (C91) Uhlig, A.; Schnakenberg, U.; Hintsche, R. Electroanalysis 1997, 9, 125-129. (C92) Williams, D. E.; Ellis, K.; Colville, A.; Dennison, S. J.; Laguillo, G.; Larsen, J. J. Electroanal. Chem. 1997, 432, 159-169. (C93) Zhang, H.-Q.; Lin, X.-Q. J. Electroanal. Chem. 1997, 434, 5559. (C94) Iwasaki, Y.; Niwa, O.; Morita, M.; Tabei, H.; Kissinger, P. T. Anal. Chem. 1996, 68, 3797-3800. (C95) Chao, M.-H.; Huang, H.-J. Anal. Chem. 1997, 69, 463-470. (C96) Paeschke, M.; Dietrich, F.; Uhlig, A.; Hintsche, R. Electroanalysis 1996, 8, 891-898. (C97) Gavin, P. F.; Ewing, A. G. J. Am. Chem. Soc. 1996, 118, 89328936. (C98) Gavin, P. F.; Ewing, A. G. Anal. Chem. 1997, 69, 3838-3845. (C99) Fritzen, M.; Schuhmann, W.; Lengeler, J. W.; Schmidt, H.-L. Prog. Biotechnol. 1996, 11 (Immobilized Cells), 821-827. (C100) John, R.; Ongarato, D. M.; Wallace, G. G. Electroanalysis 1996, 8, 623-629. (C101) Wehrens, R.; van der Linden, W. E. Anal. Chim. Acta 1996, 334, 93-101. (C102) Niwa, O.; Morita, M.; Solomon, B. P.; Kissinger, P. T. Electroanalysis 1996, 8, 427-433. (C103) Liang, X.-Z.; Palsmeier, R. K.; Lunte, C. E. J. Pharm. Biomed. Anal. 1995, 14, 113-119. (C104) Fung, Y.-S.; Mo, S.-Y. Anal. Sci. Technol. 1995, 8, 575-582. (C105) Zhong, M.; Zhou, J.; Lunte, S. M.; Zhao, G.; Giolando, D. M.; Kirchhoff, J. R. Anal. Chem. 1996, 68, 203-207. (C106) Morita, M.; Niwa, O. NTT Rev. 1996, 8, 77-80. (C107) Niwa, O.; Morita, M. Anal. Chem. 1996, 68, 355-359. (C108) Polonsky, J.; Rievaj, M.; Bustin, D. Chem. Anal. (Warsaw) 1997, 42, 445-450. (C109) Toda, K.; Hashiguchi, S.; Oguni, S.; Sanemasa, I. Anal. Sci. 1997, 13, 981-986. (C110) Cox, J. A.; Alber, K. S. J. Electrochem. Soc. 1996, 143, L126L128. (C111) Nakatani, K.; Terui, N.; Hasebe, K.; Kitamura, N. Chem. Lett. 1996, 6, 457-458. (C112) Smith, R. L.; Hsueh, Y.-T.; Collins, S. D.; Fiaccabrino, J.-C.; Koudelka, M. Proc. SPIE-Int. Soc. Opt. Eng. 1997, 2978 (Micro- and Nanofabricated Electrooptical Mechanical Systems for Biomedical and Environmental Applications), 64-68. (C113) Bustin, D.; Jursa, S.; Tomcik, P. Analyst (Cambridge, U.K.) 1996, 121, 1795-1799. (C114) Tomcik, P.; Jursa, S.; Mesaros, S.; Bustin, D. J. Electroanal. Chem. 1997, 423, 115-118. (C115) Jolley, S.; Koppang, M.; Jackson, T.; Swain, G. M. Anal. Chem. 1997, 69, 4099-4107. (C116) Horiuchi, T.; Torimitsu, K.; Yamamaoto, K.; Niwa, O. Electroanalysis 1997, 9, 912-916. 578R

Analytical Chemistry, Vol. 70, No. 12, June 15, 1998

(C117) Downard, A. J.; Lenihan, R. J.; Simpson, S. L.; O’Sullivan, B.; Powell, K. J. Anal. Chim. Acta 1997, 345, 5-15. (C118) Haghighi, B.; Safavi, A. Anal. Chim. Acta 1997, 354, 43-50. (C119) Karatani, H.; Kojima, M.; Minakuchi, H.; Soga, N.; Shizuki, T. Anal. Chim. Acta 1997, 337, 207-215. (C120) Ren, H.; Szpylka, J.; Anderson, L. B. Anal. Chem. 1996, 68, 243-249. (C121) Takamura, K.; Fuse, T.; Kusu, F. Proc.-Electrochem. Soc. 1997, 97-19 (Chemical and Biological Sensors and Analytical Electrochemical Methods), 568-576. (C122) Bocchi, C.; Careri, M.; Groppi, F.; Mangia, A.; Manini, P.; Mori, G. J. Chromatogr., A 1996, 753, 157-170. (C123) Stubauer, G.; Seppi, T.; Lukas, P.; Obendorf, D. Anal. Chem. 1997, 69, 4469-4475. (C124) Uto, Y.; Kondo, H.; Abe, M.; Suzuki, T.; Takenaka, S. Anal. Biochem. 1997, 250, 122-124. (C125) Pamidi, P. V. A.; Parrado, C.; Kane, S. A.; Wang, J.; Smyth, M. R.; Pingarron, J. Talanta 1997, 44, 1929-1934. (C126) Masuda, S.; Okano, T.; Kamao, M.; Kanedai, Y.; Kobayashi, T. J. Pharm. Biomed. Anal. 1997, 15 (9, 10), 1497-1502. (C127) McCabe, D. R.; Maher, T. J.; Acworth, I. N. J. Chromatogr., B: Biomed. Sci. Appl. 1997, 691, 23-32. (C128) Puig, D.; Barcelo, D. J. Chromatogr., A 1997, 778(1 + 2), 313319. (C129) Lewin, U.; Efer, J.; Engewald, W. J. Chromatogr., A 1996, 730(1 + 2), 161-167. (C130) Murayama, M.; Dasgupta, P. K. Anal. Chem. 1996, 68, 12261232. (C131) Iwahashi, H. J. Chromatogr., A 1996, 753, 235-242. (C132) Turner, A. Anal. Chim. Acta 1997, 337, 315-321. (C133) Khan, G. F. Biosens. Bioelectron. 1996, 11, 1221-1227. (C134) Rohm, I.; Genrich, M.; Collier, W.; Bilitewski, U. Analyst (Cambridge, U.K.) 1996, 121, 877-881. HETEROGENEOUS/HOMOGENEOUS KINETICS (D1) Shao, H.-B.; Yu, H.-Z.; Zhao, J.-W.; Zhang, H.-L.; Liu, Z.-F. Chem. Lett. 1997, 8, 749-750. (D2) Wang, Y.-Q.; Yu, H.-Z.; Cheng, J.-Z.; Zhao, J.-W.; Cai, S.-M.; Liu, Z.-F. Langmuir 1996, 12, 5466-5471. (D3) Yu, H.-Z.; Wang, Y.-Q.; Cheng, J.-Z.; Zhao, J.-W.; Cai, S.-M.; Inokuchi, H.; Fujishima, A.; Liu, Z.-F. Langmuir 1996, 12, 2843-2848. (D4) Shen, Y.; Yashiro, A.; Sato, Y.; Uosaki, K. J. Chem. Soc. 1996, 92, 3813-3821. (D5) Li, J.; Cheng, G.; Dong, S. Thin Solid Films 1997, 293, 200205. (D6) Katz, E.; Willner, I. Langmuir 1997, 13, 3364-3373. (D7) Mukae, F.; Takemura, H.; Takehara, K. Bull. Chem. Soc. Jpn. 1996, 69, 2461-2464. (D8) Hong, H.-G. Electrochim. Acta 1997, 42, 2319-2326. (D9) Ingram, R. S.; Murray, R. W. J. Chem. Soc. 1996, 92, 39413946. (D10) Xu, J.-J.; Fang, H.-Q.; Chen, H.-Y. J. Electroanal. Chem. 1997, 426, 139-143. (D11) Finklea, H. O.; Liu, L.; Ravenscroft, M. S.; Punturi, S. J. Phys. Chem. 1996, 100, 18852-18858. (D12) Bretz, R. L.; Abrun ˜a, H. D. J. Electroanal. Chem. 1996, 408, 199-211. (D13) Tirado, J. D.; Abrun ˜a, H. D. J. Phys. Chem. 1996, 100, 45564563. (D14) Hatchett, D. W.; Stevenson, K. J.; Lacy, W. B.; Harris, J. M.; White, H. S. J. Am. Chem. Soc. 1997, 119, 6596-6606. (D15) Forster, R. J. Inorg. Chem. 1996, 35, 3394-3403. (D16) Forster, R. J.; O’Kelly, J. P. J. Phys. Chem. 1996, 100, 36953704. (D17) Forster, R. J. J. Electrochem. Soc. 1997, 144, 1165-1173. (D18) Herrero, R.; Rosa Moncelli, M.; Becucci, L.; Guidelli, R. J. Electroanal. Chem. 1997, 425, 87-95. (D19) Johnson, B. J.; Park, S,-M. J. Electrochem. Soc. 1996, 143, 1269-1276. (D20) Mu, S.; Chen, C.; Wang, J. Synth. Met. 1997, 88, 249-254. (D21) Iroh, J. O.; Wood, G. A. Eur. Polym. J. 1997, 33, 107-114. (D22) Guyard, L.; Hapiot, P.; Neta, P. J. Phys. Chem. B 1997, 101, 5698-5706. (D23) Fabre, B.; Michelet, K.; Simonet, N.; Simonet, J. J. Electroanal. Chem. 1997, 425, 67-75. (D24) Cameron, C. G.; Pickup, P. G. Chem. Commun. (Cambridge) 1997, 3, 303-304. (D25) Clarke, A. P.; Vos, J. G.; Bandey, H. L.; Hillman, A. R. J. Phys. Chem. 1995, 99, 15973-15980. (D26) Krysinski, P.; Brzostowska-Smolska, M. J. Electroanal. Chem. 1997, 424, 61-67. (D27) Zehner, R. W.; Sita, L. R. Langmuir 1997, 13, 2973-2979. (D28) Martin, T. D.; Monheit, S. A.; Niichel, R. J.; Peterson, S. C.; Campbell, C. H.; Zapien, D. C. J. Electroanal. Chem. 1997, 420, 279-290. (D29) Feng, Z. Q.; Imabayashi, S.; Kakiuchi, T.; Niki, K. J. Electroanal. Chem. 1996, 408, 15-20. (D30) Wong, L. S.; Vilker, V. L.; Yap, W. T.; Reipa, V. Langmuir 1995, 11, 4818-4822. (D31) Bobacka, J.; Grzeszczuk, M.; Ivaska, A. J. Electroanal. Chem. 1997, 427, 63-69.

(D32) Fedurco, M.; Sestakova, I.; Vesela, V. Langmuir 1996, 12, 2316-2322. (D33) Lovric, M.; Mlakar, M. Electroanalysis 1995, 7, 1121-1125. (D34) Xuan, H. T.; Maksymiuk, K.; Stroka, J.; Galus, Z. Electroanalysis 1996, 8, 34-39. (D35) Saba, J. Electrochim. Acta 1996, 41, 297-306. (D36) Bhugun, I.; Save´ant, J.-M. J. Electroanal. Chem. 1995, 395, 127-131. (D37) Dabo, P.; Menard, H.; Brossard, L. Int. J. Hydrogen Energy 1997, 22, 763-770. (D38) Valand, T. Int. J. Hydrogen Energy 1997, 22, 669-673. (D39) Simpraga, R.; Tremiliosi-Filho, G.; Qian, S. Y.; Conway, B. E. J. Electroanal. Chem. 1997, 424, 141-151. (D40) Kirk, D. W.; Thorpe, S. J.; Suzuki, H. Int. J. Hydrogen Energy 1997, 22, 493-500. (D41) Shhervedani, R. K.; Lasia, A. J. Electrochem. Soc. 1997, 144, 511-519. (D42) Castro, E. B.; de Giz, M. J.; Bonzalez, E. R.; Vilche, J. R. Electrochim. Acta 1997, 42, 951-959. (D43) Paseka, I.; Velicka, J. Electrochim. Acta 1996, 42, 237-242. (D44) Mahdavi, B.; Miousse, D.; Fournier, J.; Menard, H.; Lessard, J. Can. J. Chem. 1996, 74, 380-388. (D45) Martin, H. B.; Argoitia, A.; Landau, U.; Anderson, A. B.; Angus, J. C. J. Electrochem. Soc. 1996, 143, L133-L136. (D46) Chen, L.; Guay, D.; Lasia, A. J. Electrochem. Soc. 1996, 143, 3576-3584. (D47) Yang, T.-H.; Pyun, S.-I. J. Electroanal. Chem. 1996, 414, 127133. (D48) Green, T.; Britz, D. J. Electroanal. Chem. 1996, 412, 59-66. (D49) Markovic, N. M.; Grgur, B. N.; Ross, Jr., P. N. J. Phys. Chem. B 1997, 101, 5405-5413. (D50) Markovic, N. M.; Sarraf, S. T.; Gasteiger, H. A.; Ross, P. N., Jr. J. Chem. Soc. 1996, 92, 3719-3725. (D51) Jerkiewicz, G.; Borodzinski, J. J.; Chrzanowski, W.; Conway, B. E. J. Electrochem. Soc. 1995, 142, 3755-3763. (D52) Barber, J. H.; Conway, B. E. J. Chem. Soc. 1996, 92, 37093717. (D53) Daniele, S.; Baldo, M. A.; Simonetto, F. Anal. Chim. Acta 1996, 331, 117-123. (D54) Mello, R. M. Q.; Ticianelli, E. A. Electrochim. Acta 1997, 42, 1031-1039. (D55) Gasteiger, H. A.; Markovic, N. M.; Ross, P. N., Jr. J. Phys. Chem. 1995, 99, 16757-16767. (D56) Kurin-Csoergei, K.; Orban, M. J. Phys. Chem. 1996, 100, 19141-19147. (D57) Tammeveski, K.; Arulepp, M.; Tenno, T.; Ferrater, C.; Claret, J. Electrochim. Acta 1997, 42, 2961-2967. (D58) Ahlberg, E.; Broo, A. E. J. Electrochem. Soc. 1997, 144, 12811286. (D59) Heller-Ling, N.; Prestat, M.; Gautier, J.-L.; Koenig, J.-F.; Poillerat, G.; Chartier, P. Electrochim. Acta 1996, 42, 197202. (D60) Chang, C.-C.; Wen, T.-C. J. Electrochem. Soc. 1996, 143, 14851491. (D61) Gojkovic, S. Lj.; Zecevic, S. K.; Drazic, D. M. J. Electroanal. Chem. 1995, 399, 127-133. (D62) Tammeveski, K.; Tenno, T.; Claret, J.; Ferrater, C. Electrochim. Acta 1996, 42, 893-897. (D63) Ye, S.; Vijh, A. K.; Dao, L. H. J. Electroanal. Chem. 1996, 415, 115-121. (D64) Golabi, S. M.; Raoof, J. B. J. Electroanal. Chem. 1996, 416, 75-82. (D65) Biallozor, S.; Zalewska, T.; Lisowska-Oleksiak, A. J. Appl. Electrochem. 1996, 26, 1053-1057. (D66) Markovic, N. M.; Gasteiger, H. A.; Ross, Jr., P. N. J. Phys. Chem. 1996, 100, 6715-6721. (D67) Markovic, N. M.; Gasteiger, H. A.; Ross, P. N., Jr. J. Electrochem. Soc. 1997, 144, 1591-1597. (D68) Bowyer, W. J.; Xie, J.; Engstrom, R. C. Anal. Chem. 1996, 68, 2005-2009. (D69) Fu, Y.; Swaddle, T. W. J. Am. Chem. Soc. 1997, 119, 71377144. (D70) Marczak, S.; Wrona, P. K.; Galus, Z. J. Electroanal. Chem. 1995, 396, 419-429. (D71) Orlik, M.; Gritzner, G. J. Electroanal. Chem. 1997, 421, 121128. (D72) Hecht, M.; Fawcett, W. R. J. Electroanal. Chem. 1995, 396, 473-483. (D73) Pyati, R.; Murray, R. W. J. Am. Chem. Soc. 1996, 118, 17431749. (D74) Isaev, N.; Osteryoung, J. G. J. Electrochem. Soc. 1995, 142, 4103-4107. (D75) Shim, Y. B.; Jin, C. S.; Feng, Z. Q.; Niki, K. Electroanalysis 1996, 8, 1023-1028. (D76) Mlakar, M.; Culjak, I. Electroanalysis 1997, 9, 390-394. (D77) Kisova, L.; Gritzner, G. J. Electroanal. Chem. 1997, 428, 7379. (D78) Kirowa-Eisner, E.; Rosenblum, M.; Schwarz, M.; Gileadi, E. J. Electroanal. Chem. 1996, 410, 189-197. (D79) Gil, A. F.; Galicia, L.; Gonzalez, I. J. Electroanal. Chem. 1996, 417, 129-134. (D80) Horvat-Radosevic, V.; Kvastek, K.; Krizekar, D. Croat. Chem. Acta 1997, 70, 537-561.

(D81) Pillai, K. C.; Thangamuthu, R.; Ilangovan, G. Electroanalysis 1995, 7, 1182-1188. (D82) Zhou, H.; Dong, S. J. Electroanal. Chem. 1997, 425, 55-59. (D83) Zhou, H.; Dong, S. Electrochim. Acta 1997, 42, 1801-1807. (D84) Xu, J.; Farrington, G. C. J. Electrochem. Soc. 1995, 142, 33033309. (D85) Winkler, K.; Baranski, A. S.; Fawcett, W. R. J. Chem. Soc. 1996, 92, 3899-3904. (D86) Kravtsov, V. I.; Ivanov, V. D.; Nikiforova, T. G.; Russkikh, Y. V. Electrochim. Acta 1996, 42, 887-891. (D87) Chen, P.; McCreery, R. L. Anal. Chem. 1996, 68, 3958-3965. (D88) Koene, L.; Sluyters-Rehbach, M.; Sluyters, J. H. J. Electroanal. Chem. 1996, 402, 57-72. (D89) Diao, G.; Zhang, Z. J. Electroanal. Chem. 1996, 414, 177181. (D90) Li, M. X.; Li, N. Q.; Gu, Z. N.; Zhou, X. H.; Sun, Y. L.; Wu, Y. Q. Electroanalysis 1997, 9, 490-493. (D91) Scherer, M. M.; Westall, J. C.; Ziomek-Moroz, M.; Tratnyek, P. G. Environ. Sci. Technol. 1997, 31, 2385-2391. (D92) Hori, Y.; Takahashi, R.; Yoshinami, Y.; Murata, A. J. Phys. Chem. B 1997, 101, 7075-7081. (D93) Hu, K.; Evans, D. H. J. Electroanal. Chem. 1997, 423, 29-35. (D94) Jackowska, K.; Skompska, M.; Przyluska, E. J. Electroanal. Chem. 1996, 418, 35-39. (D95) Rreedhar, N. Y.; Reddy, P. R.; Reddy, S. J. Bull. Electrochem. 1997, 13, 88-91. (D96) Babaei, A.; McQuillan, A. J. J. Phys. Chem. B 1997, 101, 74437447. (D97) Hoon, M.; Fawcett, W. R. J. Phys. Chem. A 1997, 101, 37263730. (D98) Bhugun, I.; Lexa, D.; Save´ant, J.-M. J. Am. Chem. Soc. 1996, 118, 3982-3983. (D99) Grass, V.; Lexa, D.; Save´ant, J.-M. J. Am. Chem. Soc. 1997, 119, 7526. (D100) Bhugun, I.; Lexa, D.; Save´ant, J.-M. J. Am. Chem. Soc. 1996, 118, 1769. (D101) Save´ant, J.-M.; Bhugun, I.; Lexa, D. J. Phys. Chem. 1996, 100, 19981. (D102) Gennaro, A.; Isse, A. A.; Save´ant, J.-M.; Severin, M.-G.; Vianello, E. J. Am. Chem. Soc. 1996, 118, 7190-7196. (D103) Bourdillon, C.; Demaille, C.; Save´ant, J.-M. J. Am. Chem. Soc. 1995, 117, 11499. (D104) Anicet, N.; Bourdillon, C.; Save´ant, J.-M. J. Electroanal. Chem. 1996, 410, 199. (D105) Alzari, P.; Moiroux, J.; Save´ant, J.-M. J. Am. Chem. Soc. 1996, 118, 6788. (D106) Murthy, A. S.; Sharma, J. Electroanalysis 1997, 9, 726-729. (D107) Jaworki, J. S.; Leszczynski, P. Tetrahedron Lett. 1996, 37, 3553-3556. (D108) Mostafa-Hossain, A. G. M.; Nagaoka, T.; Ogura, K. Electrochim. Acta 1997, 42, 2577-2585. (D109) Shao, Y.; Mirkin, M. V.; Rusling, J. F. J. Phys. Chem. B 1997, 101, 3202-3208. (D110) Dahm, C. E.; Peters, D. G. J. Electroanal. Chem. 1996, 406, 119-129. (D111) Hui, T.; Wong, K.; Shiu, K. Electroanalysis 1996, 8, 597-601. (D112) Bartlett, P. N.; Pratt, K. F. E. J. Electroanal. Chem. 1995, 397, 53-60. (D113) Limoges, B.; Degrand, C. J. Electroanal. Chem. 1997, 422, 7-12. (D114) Tong, J.; Dang, X. J.; Li, H. L. Electroanalysis 1997, 9, 165168. (D115) Shi, C.; Anson, F. C. Inorg. Chem. 1995, 34, 4554-61. (D116) Mu, L.; Bu, X.; Zhou, Y.; Huang, J.; Hu, X.; Shen, P. J. Coord. Chem. 1996, 39, 161-168. (D117) Tsionsky, M.; Bard, A. J.; Mirkin, M. V. J. Phys. Chem. 1996, 100, 17881-17888. (D118) Dalmata, G. Electrochim. Acta 1997, 42, 1307-1314. (D119) Ge, J.; Johnson, D. C. J. Electrochem. Soc. 1995, 142, 34203423. (D120) Yu, A. M.; Zhang, H. L.; Chen, H. Y. Electroanalysis 1997, 9, 788-790. (D121) Che, G.; Dong, S. Electrochim. Acta 1996, 41, 381-388. (D122) Bhugun, I.; Anson, F. C. Inorg. Chem. 1996, 35, 7253-7259. (D123) Choi, Y.; Jeon, S.; Park, J.; Chjo, K. Electrochim. Acta 1997, 42, 1287-1293. (D124) Zhou, D.; Ju, H.; Chen, H. J. Electroanal. Chem. 1996, 408, 219-223. (D125) Kamau, G. N.; Rusling, J. F. Langmuir 1996, 12, 2645-2649. (D126) Nassar, A. F.; Bobbitt, J. M.; Stuart, J. D.; Rusling, J. F. J. Am. Chem. Soc. 1995, 117, 10986-10993. (D127) Sun, W. L.; Kong, J. L.; Deng, J. Q. Electroanalysis 1997, 9, 115-119. (D128) Scharf, U.; Grabner, E. W. Electrochim. Acta 1996, 41, 233239. (D129) Ciszewski, A.; Milczarek, G. J. Electroanal. Chem. 1997, 426, 125-130. (D130) Ma, L.; Li, H. Electroanalysis 1995, 7, 756-758. (D131) Komura, T.; Kobayashi, T.; Yamaguti, T.; Takahasi, K. Bull. Chem. Soc. Jpn. 1997, 70, 1061-1067. (D132) Shi, C.; Anson, F. C. Inorg. Chem. 1995, 34, 4554-4561. (D133) Castrillejo, Y.; Martinez, A. M.; Vega, M.; Sanchez Batanero, P. J. Appl. Electrochem. 1996, 26, 1279-1285.

Analytical Chemistry, Vol. 70, No. 12, June 15, 1998

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(D134) Castrillejo, Y.; Martinez, A. M.; Vega, M.; Barrado, E.; Picard, G. J. Electroanal. Chem. 1995, 397, 139-147. (D135) Castrillejo, Y.; Abejon, C.; Vega, M.; Pardo, R.; Barrado, E. Electrochim. Acta 1997, 42, 1495-1506. (D136) Castrillejo, Y.; Palmero, S.; Garcia, M. A.; Deban, L.; Sanchez Batanero, P. Electrochim. Acta 1996, 41, 2461-2468. (D137) Castrillejo, Y.; Garcia, M. A.; Barrado, E.; Pasquier, P.; Picard, G. Electrochim. Acta 1995, 40, 2731-2738. (D138) Castrillejo, Y.; Martinez, A. M.; Pardo, R.; Haarberg, G. M. Electrochim. Acta 1997, 42, 1869-1876. (D139) Kisza, A.; Kazmierczak, J.; Borresen, B.; Haarberg, G. M.; Tunold, R. J. Electrochem. Soc. 1997, 144, 1646-1651. (D140) Boerresen, B.; Haarberg, G. M.; Tunold, R. Electrochim. Acta 1997, 42, 1613-1622. (D141) Nishina, T.; Ohuchi, S.; Yamada, K.; Uchida, I. J. Electroanal. Chem. 1996, 408, 181-187. (D142) Arurault, L.; Bouteillon, J.; Poignet, J. C. J. Electrochem. Soc. 1995, 142, 3351-3356. (D143) Liu, J. S.-Y.; Chen, P.-Y.; Sun, I.-W.; Hussey, C. L. J. Electrochem. Soc. 1997, 144, 2388-2392. (D144) Gau, W.-J.; Sun, I.-W. J. Electrochem. Soc. 1996, 143, 914919. (D145) Carlin, R. T.; Trulove, P. C.; Mantz, R. A.; O’Dea, J. J.; Osteryoung, R. A. J. Chem. Soc. 1996, 92, 3969-3973. (D146) Williams, M. E.; Masui, H.; Long, J. W.; Malik, J.; Murray, R. W. J. Am. Chem. Soc. 1997, 119, 1997-2005. (D147) Marken, F.; Eklund, J. C.; Compton, R. G. J. Electroanal. Chem. 1995, 395, 335-338. (D148) Jung, C. G.; Chapelle, F.; Fontana, A. Ultrason. Sonochem. 1997, 4, 117-120. (D149) Madigan, N. A.; Coury, L. A., Jr. Anal. Chem. 1997, 69, 5-15. (D150) Madigan, N. A. Electrochem. Soc. Interface 1996, 5, 56-57. (D151) Birkin, P. R.; Silva-Martinez, S. Anal. Chem. 1997, 69, 20552062. (D152) Dezhkunov, N. V.; Kulak, A. I.; Francescutto, A. Ultrasonics 1996, 34, 551-553. (D153) Walton, D. J.; Burke, L. D.; Murphy, M. M. Electrochim. Acta 1996, 41, 2747-2751. (D154) Reisse, J.; Caulier, T.; Deckerkheer, C.; Fabre, O.; Vandercammen, J.; Delplancke, J. L.; Winand, R. Ultrason. Sonochem. 1996, 3, S147-S151. (D155) Compton, R. G.; Marken, F.; Rebbitt, T. O. Chem. Commun. (Cambridge) 1996, 9, 1017-1018. (D156) Pomykal, K. E.; Lewis, N. S. J. Phys. Chem. B 1997, 101, 2476-2484. (D157) Tan, M. X.; Lewis, N. S. Inorg. Chim. Acta 1996, 242, 311321. (D158) Pomykal, K. E.; Fajardo, A. M.; Lewis, N. S. J. Phys. Chem. 1996, 100, 3652-3664. (D159) Groner, M. D.; Watts, D. K.; Koval, C. A. J. Electrochem. Soc. 1997, 144, 1690-1696. (D160) Bergmann, F.; Handschuh, M.; Lorenz, W. Chem. Phys. 1997, 215, 157-166. (D161) Lu, H. P.; Xie, X. S. J. Phys. Chem. B 1997, 101, 2753-2757. (D162) Yan, S. G.; Hupp, J. T. J. Phys. Chem. 1996, 100, 6867-6870. (D163) Reis, J. C. R. J. Electrochem. Soc. 1997, 144, 2404-2409. (D164) Koper, M. T. M. J. Phys. Chem. B 1997, 101, 3168-3173. (D165) Matthews, D. Aust. J. Chem. 1995, 48, 1843-1852. (D166) Schmickler, W. Electrochim. Acta 1996, 41, 2329-2338. (D167) Gao, Y.-D.; Lipkowitz, K. B.; Schultz, F. A. J. Am. Chem. Soc. 1995, 117, 11932-11938. (D168) Selmarten, D. C.; Hupp, J. T. J. Chem. Soc. 1996, 92, 39093916. (D169) Bieniasz, L. K. J. Electroanal. Chem. 1996, 406, 33-43. (D170) Bieniasz, L. K. J. Electroanal. Chem. 1996, 406, 45-52. (D171) Feldberg, S. W.; Goldstein, C. I. J. Electroanal. Chem. 1995, 397, 1-10. (D172) Bott, A. W.; Feldberg, S. W.; Rudolph, M. Curr. Sep. 1996, 15, 67-71. (D173) Alden, J. A.; Hutchinson, F.; Compton, R. G. J. Phys. Chem. B 1997, 101, 949-958. (D174) O’Dea, J. J.; Osteryoung, J. G. Anal. Chem. 1997, 69, 650658. (D175) Xie, Y.; Anson, F. C. J. Electroanal. Chem. 1996, 404, 209213. SURFACE ELECTROCHEMISTRY (E1) Jerkiewicz, G. ACS Symp. Ser. 1997, No. 656 (Solid-Liquid Electrochemical Interfaces), 1-12. (E2) Weaver, M. J. J. Phys. Chem. 1996, 100, 13079-13089. (E3) Schmickler, W. Chem. Rev. 1996, 96, 3177-3200. (E4) Dakkouri, A. S.; Dietterle, M.; Kolb, D. M. Festkoerperprobleme 1997, 36, 1-31. (E5) Ward, M. D.; White, H. S. Chem. Anal. (N.Y.) 1996, 139 (Modern Techniques in Electroanalysis), 107-149. (E6) Andersen, J. E. T.; Kornyshev, A.; Kuznetsov, A. M.; Moeller, P.; Ulstrup, J. In Ladungsspeicherung Doppelschicht, Tagungsband, Ulmer Elektrochem. Tage, 2nd, Meeting Date 1994; Schmickler, W., Ed.; Universitaetsverlag Ulm: Ulm, Germany, 1995; pp 101-111. (E7) Soriaga, M. P.; Harrington, D. A.; Stickney, J. L.; Wieckowski, A. Mod. Aspects Electrochem. 1996, 28, 1-60. 580R

Analytical Chemistry, Vol. 70, No. 12, June 15, 1998

(E8) Special Issue. Double Layer Modeling. Electrochim. Acta 1996, 41, 2071-2338. (E9) Saradha, R.; Sangaranarayanan, M. V. Langmuir 1997, 13, 5470-5475. (E10) Emets, V. V.; Damaskin, B. B.; Kazarinov, V. E. Russ. J. Electrochem. (Transl. of Elektrokhimiya) 1996, 32, 1313-1319. (E11) Grafov, B. M.; Damaskin, B. B. Electrochim. Acta 1996, 41, 2707-2714. (E12) Brodsky, A. Electrochim. Acta 1996, 41 (14, Double Layer Modeling), 2071-2078. (E13) Amokrane, S. Electrochim. Acta 1996, 41 (14, Double Layer Modeling), 2097-2105. (E14) Ennis, J.; Marcelja, S.; Kjellander, R. Electrochim. Acta 1996, 41 (14, Double Layer Modeling), 2115-2124. (E15) Andreu, R.; Molero, M.; Calvente, J. J.; Outhwaite, C. W.; Bhuiyan, L. B. Electrochim. Acta 1996, 41 (14, Double Layer Modeling), 2125-2130. (E16) Nazmutdinov, R. R.; Shapnik, M. S. Electrochim. Acta 1996, 41 (14, Double Layer Modeling), 2253-2265. (E17) Nazmutdinov, R. R.; Tsirlina, G. A.; Kharkats, Y. I.; Petrii, O. A.; Probst, M. J. Phys. Chem. B 1998, 102, 677-686. (E18) Kuklin, R. N. Russ. J. Electrochem. (Transl. of Elektrokhimiya) 1996, 32, 613-617. (E19) (a) Ponomarev, E. A.; Peter, L. M. J. Electroanal. Chem. 1995, 396, 219-226. (b) Pomykal, K. E.; Fajardo, A. M.; Lewis, N. S. J. Phys. Chem. 1996, 100, 3652-3664. (E20) Villegas, I.; Weaver, M. J. Electrochim. Acta 1996, 41, 661673. (E21) Villegas, I.; Weaver, M. J. J. Phys. Chem. 1996, 100, 1950219511. (E22) Villegas, I.; Weaver, M. J. J. Am. Chem. Soc. 1996, 118, 458466. (E23) Weaver, M. J.; Villegas, I. Langmuir 1997, 13, 6836-6844. (E24) Shingaya, Y.; Ito, M. Surf. Sci. 1997, 386, 34-47. (E25) Benedetti, L.; Fontanesi, C. Curr. Top. Electrochem. 1994, 3, 61-76. (E26) Yang, W.-h.; Hulteen, J.; Schatz, G. C.; Van Duyne, R. P. J. Chem. Phys. 1996, 104, 4313-4323. (E27) Retter, U.; Kant, W. Langmuir 1997, 13, 4716-4721. (E28) Pushpalatha, K.; Sangaranarayanan, M. V. J. Electroanal. Chem. 1997, 425, 39-48. (E29) Narumi, H. Bull. Chem. Soc. Jpn. 1997, 70, 1777-1785. (E30) Ignaczak, A.; Gomes, J. A. N. F. J. Electroanal. Chem. 1997, 420, 71-78. (E31) Zurita, S.; Rubio, J.; Illas, F. Electrochim. Acta 1996, 41 (14, Double Layer Modeling), 2275-2283. (E32) Lukowczyk, J.; Engler, C. Z. Phys. Chem. (Munich) 1998, 203, 159-182. (E33) Lambert, D. K. Electrochim. Acta 1996, 41, 623-630. (E34) Zou, S.; Weaver, M. J. J. Phys. Chem. 1996, 100, 4237-4242. (E35) (a) Schmidt, M. E.; Guyot-Sionnest, P. J. Chem. Phys. 1996, 104, 2438-2445. (b) Nart, F. C.; Iwasita, T. Electrochim. Acta 1996, 41, 631-636. (E36) Tadano, A.; Aogaki, R. J. Chem. Phys. 1997, 106, 6126-6137. (E37) Tadano, A.; Aogaki, R. J. Chem. Phys. 1997, 106, 6138-6145. (E38) Cohen, R. R.; Radke, C. J. J. Electroanal. Chem. 1996, 405, 23-32. (E39) Soper, M. T. M.; Schmickler, W. Chem. Phys. 1996, 211 (13), 123-133. (E40) Kim, S.; Wang, Z.; Scherson, D. A. J. Phys. Chem. B 1997, 101, 2735-2740. (E41) Brown, G. M.; Hope, G. A. J. Electroanal. Chem. 1995, 397, 293-300. (E42) Kreisig, S.; Tarazona, A.; Koglin, E. Electrochim. Acta 1997, 42, 3335-3344. (E43) Dobberpuhl, D. A.; Johnson, D. C. Electroanalysis 1996, 8, 726-731. (E44) Campbell, D. J.; Herr, B. R.; Hulteen, J. C.; Van Duyne, R. P.; Mirkin, C. A. J. Am. Chem. Soc. 1996, 118, 10211-10219. (E45) Sabapathy, R. C.; Bhattacharyya, S.; Leavy, M. C.; Cleland, W. E., Jr.; Hussey, C. L. Langmuir 1998, 14, 124-136. (E46) Yamada, T.; Ogaki, K.; Okubo, S.; Itaya, K. Surf. Sci. 1996, 369, 321-335. (E47) Mayer, T.; Pettenkofer, C.; Jaegermann, W. J. Phys. Chem. 1996, 100, 16966-16977. (E48) Tian, Z. Q.; Ren, B.; Mao, B. W. J. Phys. Chem. B 1997, 101, 1338-1346. (E49) Pastor, E.; Rodriguez, J. L.; Castro, C. M.; Gonzalez, S. J. Braz. Chem. Soc. 1997, 8, 107-112. (E50) Wu, S.; Shi, Z.; Lipkowski, J.; Hitchcock, A. P.; Tyliszczak, T. J. Phys. Chem. 1997, 101, 10310-10322. (E51) Yau, S.-L.; Kim, Y.-G.; Itaya, K. Anal. Sci. Technol. 1995, 8, 723-730. (E52) Staikov, G.; Lorenz, W. J. Proc.-Electrochem. Soc. 1997, 9619 (Electrochemically Deposited Thin Films), 3-20. (E53) Lovric, M.; Scholz, F. Electroanalysis 1997, 9, 1189-1196. (E54) Zhang, J.; Rikvold, P. A.; Sung, Y.-E.; Wieckowski, A. Springer Proc. Phys. 1995, 80 (Computer Simulation Studies in Condensed-Matter Physics VIII), 122-128. (E55) Legault, M.; Blum, L.; Huckaby, D. A. J. Electroanal. Chem. 1996, 409, 79-86.

(E56) Blum, L.; Huckaby, D. A.; Legault, M. Electrochim. Acta 1996, 41 (14, Double Layer Modeling), 2207-2227. MODIFIED ELECTRODES (F1) Durst, R. A.; Baumner, A. J.; Murray, R. W.; Buck, R. P.; Andrieux, C. P. Pure Appl. Chem. 1997, 69, 1317-1323. (F2) Cox, J. A.; Tess, M. E.; Cummings, T. E. Rev. Anal. Chem. 1996, 15, 173-223. (F3) Mallouk, T. E.; Kim, H.-N.; Ollivier, P. J.; Keller, S. W. In Comprehensive Supramolecular Chemistry; Alberti, G., Bein, T., Eds.; Elsevier: Oxford, U.K.; 1996; pp 189-217. (F4) Buck, R. P.; Mundt, C. J. Chem. Soc., Faraday Trans. 1996, 92, 4987-4992. (F5) Nikitas, P. Electrochim. Acta 1996, 41, 2159-2170. (F6) Calvente, J.-J.; Kovacova, Z.; Andreu, R.; Fawcett, W. R. J. Chem. Soc., Faraday Trans. 1996, 92, 3701-3708. (F7) Cassidy, J.; McCormac, T. Electroanalysis 1996, 8, 139-42. (F8) Vorotyntsev, M. A.; Badiali, J. P.; Vieil, E. Electrochim. Acta 1996, 41, 1375-1381. (F9) Pater, E.; Bruckenstein, S.; Hillman, A. R. J. Chem. Soc., Faraday Trans. 1996, 92, 4087-4092. (F10) Hillman, A. R.; Bandey, H. L.; Gonsalves, M.; Bruckenstein, S.; Pater, E. Ann. Chim. 1997, 87, 177-186. (F11) Aldrin Denny, R.; Sangaranarayanan, M. V. Chem. Phys. Lett. 1995, 239, 131-135. (F12) Lyons, M. E. G.; Greer, J. C.; Fitzgerald, C. A.; Bannon, T.; Barlett, P. N. Analyst 1996, 121, 715-731. (F13) Desprez, V.; Labbe, P. J. Electroanal. Chem. 1996, 415, 191195. (F14) Sorochinskii, V. V.; Kurganov, B. I. J. Chem. Biochem. Kinet. 1992, 2, 247-51. (F15) Vorotyntsev, M. A.; Vieil, E.; Heinze, J. Electrochim. Acta 1996, 41, 1913-1920. (F16) Bhugun, I.; Save´ant, J.-M. J. Electroanal. Chem. 1995, 395, 127-131. (F17) Alleman, K. S.; Weber, K.; Creager, S. E. J. Phys. Chem. 1996, 100, 17050-17058. (F18) Ohtani, M.; Kuwabata, S.; Yoneyama, H. Anal. Chem. 1997, 69, 1045-1053. (F19) Andreu, R.; Calvente, J. J.; Fawcett, W. R.; Molero, M. J. Phys. Chem. B 1997, 101, 2884-2894. (F20) Lovell, M. R.; Roser, S. J. Langmuir 1996, 12, 2765-2773. (F21) Gould, S.; Leasure, R. M.; Meyer, T. J. Chem. Br. 1995, 31, 891-893. (F22) Schanze, K. S.; Bergstedt, T. S.; Hauser, B. T. Adv. Mater. 1996, 8, 531-534. (F23) Harima, Y.; Matsumoto, K.; Wang, Y.-D.; Yamashita, K. Thin Solid Films 1997, 301, 95-104. (F24) Hoyer, B.; Sorensen, G.; Jensen, N.; Nielsen, D. B.; Larsen, B. Anal. Chem. 1996, 68, 3840-3844. (F25) Wittstock, G.; Hesse, R.; Schuhmann, W. Electroanalysis 1997, 9, 746-750. (F26) Tender, L. M.; Worley, R. L.; Fan, H.; Lopez, G. P. Langmuir 1996, 12, 5515-5518. (F27) Nyffenegger, R. M.; Penner, R. M. J. Phys. Chem. 1996, 100, 17041-17049. (F28) Zhou, J.; Wipf, D. J. Electrochem. Soc. 1997, 144, 1202-1207. (F29) MacDiarmid, A. G.; Zhang, W. J.; Wang, H. P. C.; Huang, F.; Xie, S. Polym. Prepr. (Am. Chem. Soc., Div. Polym. Chem.) 1997, 38, 333-334. (F30) Gardner, T. J.; Frisbie, C. D.; Wrighton, M. S. J. Am. Chem. Soc. 1995, 117, 6927-933. (F31) Moss, J. A.; Argazzi, R.; Bignozzi, C. A.; Meyer, T. J. Inorg. Chem. 1997, 36, 762-763. (F32) Sun, F.; Castner, D. G.; Mao, G.; Wang, W.; McKeown, P.; Grainger, D. W. J. Am. Chem. Soc. 1996, 118, 1856-66. (F33) Jennings, G. K.; Laibinis, P. E. Langmuir 1996, 12, 61736175. (F34) Andrieux, C. P.; Gonzalez, F.; Save´ant, J.-M. J. Am. Chem. Soc. 1997, 119, 4292-4300. (F35) Allongue, P.; Delamar, M.; Desbat, B.; Fagebaume, O.; Hitmi, R.; Pinson, J.; Save´ant, J.-M. J. Am. Chem. Soc. 1997, 119, 201-207. (F36) Gabrielli, C. In Physical Electrochemistry; Rubinstein, I., Ed.; Dekker: New York, 1995; pp 243-292. (F37) Ugo, P.; Moretto, L. M. Electroanalysis 1995, 7, 1105-1113. (F38) Armstrong, F. A.; Heering, H. A.; Hirst, J. Chem. Soc. Rev. 1997, 26, 169-179. (F39) Stratmann, M.; Furbeth, W. Comm. Eur. Communities, [Rep.] EUR 1997, 16490, 59-90. (F40) Bruckenstein, S.; Hillman, A. R. Handbook of Surface Imaging; Hubbard, A. T., Ed.; CRC Press: Boca Raton, FL, 1995; pp 101-103. (F41) Oyama, N.; Ohsaka, T. Prog. Polym. Sci. 1995, 20, 761-818. (F42) Ward, M. D. In Physical Electrochemistry; Rubinstein, I., Ed.; Dekker: New York, 1995; pp 292-338. (F43) Horanyi, G. Rev. Anal. Chem. 1995, 14, 1-58. (F44) Inzelt, G. Electroanalysis 1995, 7, 895-903. (F45) Bard, A. J.; Fan, F.-R.; Mirkin, M. In Physical Electrochemistry; Rubinstein, I., Ed.; Dekker: New York, 1995; pp 209-242. (F46) Borgwarth, K.; Ricken, C.; Ebling, D. G.; Heinze, J. Ber. GunsenGes. 1995, 99, 1421-1426.

(F47) Bard, A. J.; Fan, F.-R. F.; Mirkin, M. V. In Handbook of Surface Imaging; Hubbard, A. T., Ed.; CRC Press: Boca Raton, FL, 1995; pp 667-679. (F48) Berger, R.; Gerber, C.; Lang, H. P.; Gimzewski, J. K. Microelectron. Eng. 1997, 35, 373-379. (F49) Bottomley, L. A.; Coury, J. E.; First, P. N. Anal. Chem. 1996, 68, 185-230. (F50) Majkrzak, C. F. Mater. Res. Soc. Symp. Proc. 1995, 376, 14356. (F51) Gottesfeld, S.; Kim, Y.-T.; Redondo, A. In Physical Electrochemistry; Rubinstein, I., Ed.; Dekker: New York, 1995; pp 393467. (F52) Aoki, K.; Cao, J. J. Electroanal. Chem. 1997, 428, 97-103. (F53) Bernard, P.; Keddam, M.; Takenouti, H. J. Electroanal. Chem. 1995, 396, 325-332. (F54) Jeffcoate, C. S.; Li, J.; Bierwagen, G. P. Proc.-Electrochem. Soc. 1997, 95-16, 60-71. (F55) Kubiak, W. W.; Wang, J. Anal. Chim. Acta 1996, 329, 181189. (F56) Zhang, J.; Yagi, M.; Hou, X.; Kaneko, M. J. Electroanal. Chem. 1996, 412, 159-164. (F57) Daniele, S.; Ugo, P.; Bragato, C.; Mazzocchin, G. A. J. Electroanal. Chem. 1996, 418, 29-34. (F58) Snyder, S. R.; White, H. S. J. Electroanal. Chem. 1995, 394, 177-185. (F59) James, P.; Casillas, N.; Smyrl, W. H. J. Electrochem. Soc. 1996, 143, 3853-3865. (F60) Fantini, J.; Fournier, D.; Boccara, A. C.; Plichon, V. Electrochim. Acta 1997, 42, 937-944. (F61) Zwickl, T.; Schneider, B.; Federer, B.; Sokalski, T.; Lindner, E.; Schaller, U.; Cimerman, Z.; Pretsch, E. Proc.-Electrochem. Soc. 1997, 97-19, 1080-1089. (F62) Hudson, J. E.; Abrun ˜a, H. D. J. Am. Chem. Soc. 1996, 118, 6303-6304. (F63) Schindler, W.; Kirschner, J. Rev. Sci. Instrum. 1996, 67, 35783582. (F64) Hillman, A. R. Solid State Ionics 1997, 94, 151-160. (F65) Lau, O.-W.; Shao, B. Anal. Chim. Acta 1997, 343, 85-92. (F66) Slaterbeck, A. F.; Shi, Y.; Seliskar, C. J.; Ridgway, T. H.; Heineman, W. R. Proc.-Electrochem. Soc. 1997, 97-19, 5060. (F67) Dunphy, D. R.; Mendes, S. B.; Saavedra, S. S.; Armstrong, N. R. Anal. Chem. 1997, 69, 3086-3094. (F68) Rosenmund, J.; Doblhofer, K. J. Electroanal. Chem. 1995, 396, 77-83. (F69) Shultz, L. L.; Stoyanoff, J. S.; Nieman, T. A. Anal. Chem. 1996, 68, 349-354. (F70) Chamberlain, J. R.; Pemberton, J. E. Langmuir 1997, 13, 3074-3079. (F71) Deng, Z.; Spear, J. D.; Rudnicki, J. D.; McLarnon, F. R.; Cairns, E. J. J. Electrochem. Soc. 1996, 143, 1514-1521. (F72) Zimmermann, A.; Dunsch, L. J. Mol. Struct. 1997, 410-411, 165-171. (F73) Ping, Z.; Nauer, G. E.; Neugebauer, H.; Theiner, J. J. Electroanal. Chem. 1997, 420, 301-306. (F74) Bae, I. T.; Sandifer, M.; Lee, Y. W.; Tryk, D. A.; Sukenik, C. N.; Scherson, D. A. Anal. Chem. 1995, 67, 4508-4513. (F75) Bonazzola, C.; Brust, M.; Calvo, E. J. J. Electroanal. Chem. 1996, 407, 203-207. (F76) Hanken, D. G.; Corn, R. M. Anal. Chem. 1997, 69, 36653673. (F77) Barnes, A.; Despotakis, A.; Wong, T. C. P.; Anderson, A. P.; Chambers, B.; Wright, P. V. Proc. SPIE-Int. Soc. Opt. Eng. 1997, 3039, 704-714. (F78) Bizzotto, D.; Lipkowski, J. Prog. Surf. Sci. 1995, 50, 237246. (F79) Cruanes, M. T.; Drickamer, H. G.; Faulkner, L. R. J. Phys. Chem. 1996, 100, 16613-16620. (F80) Koetz, J.; Koepke, H.; Schmidt-Naake, G.; Zarras, P.; Vogl, O. Polymer 1996, 37, 2775-2781. (F81) Joerissen, J. Electrochim. Acta 1996, 41, 553-62. (F82) Harth, R.; Ozer, D.; Hayon, J.; Ydgar, R.; Bettelheim, A. Curr. Top. Electrochem. 1994, 3, 531-543. (F83) Bontempelli, G.; Comisso, N.; Toniolo, R.; Schiavon, G. Electroanalysis 1997, 9, 433-443. (F84) Rusling, J. F. Prog. Colloid Polym. Sci. 1997, 103, 170-180. (F85) Simonet, J. Curr. Top. Electrochem. 1994, 3, 227-264. (F86) Alberti, G.; Casciola, M. Solid State Ionics 1997, 97, 177186. (F87) Mafe, S.; Ramirez, P. Acta Polym. 1997, 48, 234-250. (F88) Shi, M.; Anson, F. C. J. Electroanal. Chem. 1996, 415, 4146. (F89) Zook, L. A.; Leddy, J. Anal. Chem. 1996, 68, 3793-3796. (F90) Shao, Y.; Mirkin, M. V.; Fish, G.; Kokotov, S.; Palanker, D.; Lewis, A. Anal. Chem. 1997, 69, 1627-1634. (F91) Matysik, F.-M.; Matysik, S.; Brett, A. M. O.; Brett, C. M. A. Anal. Chem. 1997, 69, 1651-1656. (F92) Ugo, P.; Moretto, L. M.; Bellomi, S.; Menon, V. P.; Martin, C. R. Anal. Chem. 1996, 68, 4160-4165. (F93) Laurent, D.; Schlenoff, J. B. Langmuir 1997, 13, 1552-1557. (F94) Tasaka, M.; Kiyono, R.; Kodaka, H.; Niimi, Y.; Nagasawa, M. J. Membr. Sci. 1997, 126, 1-6.

Analytical Chemistry, Vol. 70, No. 12, June 15, 1998

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(F95) Pihel, K.; Walker, Q. D.; Wightman, R. M. Anal. Chem. 1996, 68, 2084-2089. (F96) Farrington, A. M.; Slater, J. M. Electroanalysis 1997, 9, 843847. (F97) Tamm, J.; Alumaa, A.; Hallik, A.; Silk, T.; Sammelselg, V. J. Electroanal. Chem. 1996, 414, 149-158. (F98) Ren, X.; Pickup, P. G. J. Electroanal. Chem. 1995, 396, 359364. (F99) Hepel, J.; Bruckenstein, S.; Hepel, M. Microchem. J. 1997, 55, 179-191. (F100) Hepel, M. Electrochim. Acta 1996, 41, 63-76. (F101) Kotov, S. V.; Pedersen, S. D.; Qiu, W.; Qiu, Z.-M.; Burton, D. J. J. Fluorine Chem. 1997, 82, 13-19. (F102) Kern, J.-M.; Sauvage, J.-P.; Bidan, G.; Billon, M.; DivisiaBlohorn, B. Adv. Mater. 1996, 8, 580-582. (F103) Abd El-Rahman, H. A.; Schultze, J. W. J. Electroanal. Chem. 1996, 416, 67-74. (F104) Bojanic, V.; Jovanovic, S.; Tabakovic, R.; Tabakovic, I. J. Appl. Polym. Sci. 1996, 60, 1719-1725. (F105) Palmore, G. T. R.; Smith, D. K.; Wrighton, M. S. J. Phys. Chem. B 1997, 101, 2437-2450. (F106) Kepley, L. J.; Bard, A. J. J. Electrochem. Soc. 1995, 142, 412938. (F107) Schlereth, D. D.; Karyakin, A. A. J. Electroanal. Chem. 1995, 395, 221-32. (F108) Chambers, J. Q.; Scaboo, K.; Evans, C. D. J. Electrochem. Soc. 1996, 143, 3039-3045. (F109) Persson, B.; Lee, H. S.; Gorton, L.; Skotheim, T.; Bartlett, P. Electroanalysis 1995, 7, 935-40. (F110) Karyakin, A. A.; Bobrova, O. A.; Karyakina, E. E. J. Electroanal. Chem. 1995, 399, 179-184. (F111) Cai, C.-X.; Xue, K.-H. J. Electroanal. Chem. 1997, 427, 147153. (F112) Cai, C. X.; Xue, K. H. Anal. Chim. Acta 1997, 343, 69-77. (F113) Kertesz, V.; Bacskai, J.; Inzelt, G. Electrochim. Acta 1996, 41, 2877-2881. (F114) Zhou, D. M.; Chen, H. Y. Electroanalysis 1997, 9, 399-402. (F115) Gao, G.; Wurm, D. B.; Kim, Y.-T.; Kispert, L. D. J. Phys. Chem. B 1997, 101, 2038-2045. (F116) Leitner, M. B.; Ruhmann, R.; Springer, J. Macromol. Chem. Phys. 1996, 197, 237-47. (F117) Wang, P.; Martin, B. D.; Parida, S.; Rethwisch, D. G.; Dordick, J. S. J. Am. Chem. Soc. 1995, 117, 12885-6. (F118) Lieder, M.; Schlaepfer, C. W. J. Appl. Electrochem. 1997, 27, 235-239. (F119) Davis, J.; Vaughan, D. H.; Cardosi, M. F. J. Electroanal. Chem. 1996, 403, 213-218. (F120) Pham, M. C.; Oulahyane, M.; Mostefai, M.; Lacaze, P. C. Synth. Met. 1997, 84, 411-412. (F121) Abdel Azzem, M. J. Electroanal. Chem. 1996, 417, 163-173. (F122) Balzani, V.; Juris, A.; Venturi, M.; Campagna, S.; Serroni, S. Chem. Rev. 1996, 96, 759-833. (F123) Ju, H.; Leech, D. J. Chem. Soc., Faraday Trans. 1997, 93, 13711375. (F124) Bandey, H. L.; Gonsalves, M.; Hillman, A. R.; Glidle, A.; Bruckenstein, S. J. Electroanal. Chem. 1996, 410, 219-227. (F125) Guelce, H.; Celebi, S. S.; Oezyoeruek, H.; Yildiz, A. Pure Appl. Chem. 1997, 69, 173-177. (F126) Rulkens, R.; Lough, A. J.; Manners, I.; Lovelace, S. R.; Grant, C.; Geiger, W. E. J. Am. Chem. Soc. 1996, 118, 12683-12695. (F127) Wang, K.; Munoz, S.; Zhang, L.; Castro, R.; Kaifer, A. E.; Gokel, G. W. J. Am. Chem. Soc. 1996, 118, 6707-6715. (F128) Yamamoto, T.; Morikita, T.; Maruyama, T.; Kubota, K.; Katada, M. Macromolecules 1997, 30, 5390-5396. (F129) Stanton, C. E.; Lee, T. R.; Grubbs, R. H.; Lewis, N. S.; Pudelski, J. K.; Callstrom, M. R.; Erickson, M. S.; McLaughlin, M. L. Macromolecules 1995, 28, 8713-8721. (F130) Bochmann, M.; Lu, J.; Cannon, R. D. J. Organomet. Chem. 1996, 518, 97-103. (F131) Pudelski, J. K.; Foucher, D. A.; Honeyman, C. H.; Macdonald, P. M.; Manners, I.; Barlow, S.; O’Hare, D. Macromolecules 1996, 29, 1894-1903. (F132) Kapoor, R. N.; Crawford, G. M.; Mahmoud, J.; Dementiev, V. V.; Nguyen, M. T.; Diaz, A. F.; Pannell, K. H. Organometallics 1995, 14, 4944-4947. (F133) Peckham, T. J.; Massey, J. A.; Edwards, M.; Manners, I.; Foucher, D. A. Macromolecules 1996, 29, 2396-2403. (F134) Gollas, B.; Speiser, B.; Sieglen, J.; Straehle, J. Organometallics 1996, 15, 260-271. (F135) Caix, C.; Chardon-Noblat, S.; Deronzier, A.; Ziessel, R. J. Electroanal. Chem. 1996, 403, 189-202. (F136) Hoefer, E.; Steckhan, E.; Ramos, B.; Heineman, W. R. J. Electroanal. Chem. 1996, 402, 115-122. (F137) Dostal, A.; Hermes, M.; Scholz, F. J. Electroanal. Chem. 1996, 415, 133-141. (F138) Chen, S.-M. J. Electroanal. Chem. 1996, 417, 145-153. (F139) Vlcek, A., Jr. Chemtracts 1997, 10, 385-390. (F140) Sato, O.; Gu, Z.; Etoh, H.; Ichiyanagi, J.-i.; Iyoda, T.; Fujishima, A.; Hashimoto, K. Chem. Lett. 1997, 37-38. (F141) Czirok, E.; Bacskai, J.; Kulesza, P. J.; Inzelt, G.; Wolkiewicz, A.; Miecznikowski, K.; Malik, M. A. J. Electroanal. Chem. 1996, 405, 205-209. (F142) Liu, C. W.; Dong, S. J. Electroanalysis 1997, 9, 838-842. 582R

Analytical Chemistry, Vol. 70, No. 12, June 15, 1998

(F143) Liu, S.; Li, H.; Jiang, M.; Li, P. J. Electroanal. Chem. 1997, 426, 27-30. (F144) Nechitayilo, V. B.; Styopkin, V. I.; Tkachenko, Z. A.; Goltsov, Y. G.; Sherstyuk, V. P.; Zhilinskaya, V. V. Electrochim. Acta 1995, 40, 2501-4. (F145) Zhang, H.-T.; Yan, S. G.; Subramanian, P.; Skeens-Jones, L. M.; Stern, C.; Hupp, J. T. J. Electroanal. Chem. 1996, 414, 2329. (F146) Yan, S. G.; Hupp, J. T. Polym. Mater. Sci. Eng. 1994, 71, 4923. (F147) Chen, S.-M. J. Electroanal. Chem. 1996, 401, 147-154. (F148) Billon, M.; Divisia-Blohorn, B.; Kern, J.-M.; Sauvage, J.-P. J. Mater. Chem. 1997, 7, 1169-1173. (F149) Bachas, L. G.; Cullen, L.; Hutchins, R. S.; Scott, D. L. J. Chem. Soc., Dalton Trans. 1997, 1571-1577. (F150) Wu, Q.; Maskus, M.; Pariente, F.; Tobalina, F.; Fernandez, V. M.; Lorenzo, E.; Abrun ˜a, H. D. Anal. Chem. 1996, 68, 36883696. (F151) Kelly, D. M.; Vos, J. G. In Electroactive Polymer Chemistry; Lyons, M. E. G., Ed.; Plenum: New York; 1994; pp 173-232. (F152) Lopez, C.; Moutet, J.-C.; Saint-Aman, E. J. Chem. Soc., Faraday Trans. 1996, 92, 1527-1532. (F153) Leasure, R. M.; Ou, W.; Moss, J. A.; Linton, R. W.; Meyer, T. J. Chem. Mater. 1996, 8, 264-273. (F154) Hauser, B. T.; Bergstedt, T. S.; Schanze, K. S. J. Chem. Soc., Chem. Commun. 1995, 1945-1946. (F155) Gould, S.; Gray, K. H.; Linton, R. W.; Meyer, T. J. J. Phys. Chem. 1995, 99, 16052-16058. (F156) Lyon, E. A.; Ratner, M. A.; Hupp, J. T. Polym. Mater. Sci. Eng. 1994, 71, 588-589. (F157) Cameron, C. G.; Pickup, P. G. Chem. Commun. 1997, 303304. (F158) Bakir, M.; Sullivan, B. P.; MacKay, S. G.; Linton, R. W.; Meyer, T. J. Chem. Mater. 1996, 8, 2461-2467. (F159) Caix, C.; Chardon-Noblat, S.; Deronzier, A.; Moutet, J.-C.; Tingry, S. J. Organomet. Chem. 1997, 540, 105-111. (F160) Ramos Sende, J. A.; Arana, C. R.; Hernandez, L.; Potts, K. T.; Keshevarz-K, M.; Abrun ˜a, H. D. Inorg. Chem. 1995, 34, 333948. (F161) Wilde, C. P.; Pisharodi, D. J. Electroanal. Chem. 1995, 398, 143-150. (F162) Chardon-Noblat, S.; Deronzier, A.; Zsoldos, D.; Ziessel, R.; Haukka, M.; Pakkanen, T.; Venalainen, T. J. Chem. Soc., Dalton Trans. 1996, 2581-2583. (F163) Grosshenny, V.; Harriman, A.; Gisselbrecht, J.-P.; Ziessel, R. J. Am. Chem. Soc. 1996, 118, 10315-10316. (F164) Paula, M. M. S.; Franco, C. V. J. Coord. Chem. 1996, 40, 7182. (F165) Lindall, C. M.; Crayston, J. A.; Cole-Hamilton, D. J.; Glidle, A.; Peacock, R. D. J. Mater. Chem. 1996, 6, 1259-1269. (F166) Crayston, J. A.; Iraqi, A.; Morrison, J. J.; Walton, J. C. Synth. Met. 1997, 84, 441-442. (F167) Storrier, G. D.; Colbran, S. B. Polyhedron 1997, 16, 27052710. (F168) Nallas, G. N. A.; Brewer, K. J. Inorg. Chim. Acta 1997, 257, 27-35. (F169) Maruyama, T.; Yamamoto, T. Inorg. Chim. Acta 1995, 238, 9-13. (F170) Maskus, M.; Abrun ˜a, H. D. Langmuir 1996, 12, 4455-4462. (F171) Storrier, G. D.; Colbran, S. B. J. Chem. Soc., Dalton Trans. 1996, 2185-2186. (F172) Ju, H.; Leech, D. Anal. Chim. Acta 1997, 345, 51-58. (F173) Bedioui, F.; Devynck, J.; Bied-Charreton, C. J. Mol. Catal. A: Chem. 1996, 113, 3-11. (F174) Dobson, D. J.; Saini, S. Anal. Chem. 1997, 69, 3532-3538. (F175) Araki, K.; Angnes, L.; Azevedo, C. M. N.; Toma, H. E. J. Electroanal. Chem. 1995, 397, 205-210. (F176) Araki, K.; Angnes, L.; Toma, H. E. Adv. Mater. 1995, 7, 554559. (F177) Hutchison, J. E.; Postlethwaite, T. A.; Chen, C.-h.; Hathcock, K. W.; Ingram, R. S.; Ou, W.; Linton, R. W.; Murray, R. W.; Tyvoll, D. A.; Chng, L. L.; Collman, J. P. Langmuir 1997, 13, 2143-2148. (F178) Choi, Y.-K.; Jeon, S.; Park, J.-K.; Chjo, K.-H. Electrochim. Acta 1997, 42, 1287-1293. (F179) Ciszewski, A.; Milczarek, G. J. Electroanal. Chem. 1997, 426, 125-130. (F180) Trevin, S.; Bedioui, F.; Villegas, M. G. G.; Bied-Charreton, C. J. Mater. Chem. 1997, 7, 923-928. (F181) Bedioui, F.; Trevin, S.; Albin, V.; Gomez Villegas, M. G.; Devynck, J. Anal. Chim. Acta 1997, 341, 177-185. (F182) Trevin, S.; Bedioui, F.; Devynck, J. J. Electroanal. Chem. 1996, 408, 261-265. (F183) Orti, E.; Crespo, R.; Piqueras, M. C.; Tomas, F. J. Mater. Chem. 1996, 6, 1751-1761. (F184) Chebotareva, N.; Nyokong, T. J. Appl. Electrochem. 1997, 27, 975-981. (F185) Qi, X.; Baldwin, R. P. J. Electrochem. Soc. 1996, 143, 12831287. (F186) Allen, J. R.; Florido, A.; Young, S. D.; Daunert, S.; Bachas, L. G. Electroanalysis 1995, 7, 710-713. (F187) Zhu, S. S.; Carroll, P. J.; Swager, T. M. J. Am. Chem. Soc. 1996, 118, 8713-8714.

(F188) Reddinger, J. L.; Reynolds, J. R. Macromolecules 1997, 30, 673-675. (F189) Lev, O.; Tsionsky, M.; Rabinovich, L.; Glezer, V.; Sampath, S.; Pankratov, I.; Gun, J. Anal. Chem. 1995, 67, 22A-30A. (F190) Aegerter, M. A.; Avellaneda, C. O. Ceram. Trans. 1995, 55, 223-234. (F191) Aegerter, M. A.; Avellaneda, C. O.; Pawlicka, A.; Atik, M. J. Sol-Gel Sci. Technol. 1997, 8, 689-696. (F192) Hsueh, C.; Collinson, M. M. J. Electroanal. Chem. 1997, 420, 243-249. (F193) Cox, J. A.; Alber, K. S.; Tess, M. E.; Cummings, T. E.; Gorski, W. J. Electroanal. Chem. 1995, 396, 485-490. (F194) Livage, J.; Guzman, G.; Beteille, F.; Davidson, P. J. Sol-Gel Sci. Technol. 1997, 8, 857-865. (F195) Tavcar, G.; Ogorevc, B.; Cai, X.; Pihlar, B. Anal. Chim. Acta 1996, 329, 239-245. (F196) Gusmano, G.; Bianco, A.; Montesperelli, G.; Traversa, E. Electrochim. Acta 1996, 41, 1359-1368. (F197) Lee, K. D. Thin Solid Films 1997, 302, 84-88. (F198) Svegl, F.; Orel, B.; Bukovec, P.; Kalcher, K.; Hutchins, M. G. J. Electroanal. Chem. 1996, 418, 53-66. (F199) Spinolo, G.; Ardizzone, S.; Trasatti, S. J. Electroanal. Chem. 1997, 423, 49-57. (F200) Bay, N. T. B.; Tien, P. M.; Badilescu, S.; Djaoued, Y.; Bader, G.; Girouard, F. E.; Truong, V.-v.; Nguyen, L. Q. J. Appl. Phys. 1996, 80, 7041-7045. (F201) Singh, R. N.; Tiwari, S. K.; Singh, S. P.; Jain, A. N.; Singh, N. K. Int. J. Hydrogen Energy 1997, 22, 557-562. (F202) Singh, R. N.; Tiwari, S. K.; Singh, S. P.; Singh, N. K.; Poillerat, G.; Chartier, P. J. Chem. Soc., Faraday Trans. 1996, 92, 25932598. (F203) Lu, X.; Zhu, R.; He, Y. Surf. Coat. Technol. 1996, 79, 19-24. (F204) Gorski, W.; Aspinwall, C. A.; Lakey, J. R. T.; Kennedy, R. T. J. Electroanal. Chem. 1997, 425, 191-199. (F205) Lewinski, K.; Hu, Y.; Griffin, C. C.; Cox, J. A. Electroanalysis 1997, 9, 675-679. (F206) Cataldi, T. R. I.; Centonze, D.; Desimoni, E.; Forastiero, V. Anal. Chim. Acta 1995, 310, 257-262. (F207) He, L.; Anderson, J. R.; Franzen, H. F.; Johnson, D. C. Chem. Mater. 1997, 9, 715-722. (F208) Conway, B. E. Prog. Surf. Sci. 1995, 49, 331-452. (F209) Wang, B.; Dong, S. Electrochim. Acta 1996, 41, 895-902. (F210) Cataldi, T. R. I.; Salvi, A. M.; Centonze, D.; Sabbatini, L. J. Electroanal. Chem. 1996, 406, 91-99. (F211) Snover, J. L.; Byrd, H.; Suponeva, E. P.; Vicenzi, E.; Thompson, M. E. Chem. Mater. 1996, 8, 1490-1499. (F212) Walcarius, A. Electroanalysis 1996, 8, 971-986. (F213) Fitch, A.; Song, J.; Stein, J. Clays Clay Miner. 1996, 44, 370380. (F214) Park, S.; Fitch, A.; Wang, Y. J. Phys. Chem. B 1997, 101, 48894896. (F215) Fitch, A.; Du, J.; Gan, H.; Stucki, J. W. Clays Clay Miner. 1995, 43, 607-614. (F216) Stein, J. A.; Fitch, A. Clays Clay Miner. 1996, 44, 381-392. (F217) Porter, T. L.; Thompson, D.; Bradley, M. J. Vac. Sci. Technol., A 1997, 15, 500-504. (F218) Hotta, Y.; Taniguchi, M.; Inukai, K.; Yamagishi, A. Clay Miner. 1997, 32, 79-88. (F219) Joo, P.; Fitch, A.; Mellican, S.; Macha, S. NATO ASI Ser., Ser. 3 1996, 18, 529-541. (F220) Petridis, D.; Kaviratna, P. D. S.; Pinnavaia, T. J. J. Electroanal. Chem. 1996, 410, 93-99. (F221) Bessel, C. A.; Rolison, D. R. J. Phys. Chem. B 1997, 101, 11481157. (F222) Wang, J.; Walcarius, A. J. Electroanal. Chem. 1996, 407, 183187. (F223) Yuasa, M.; Nagaiwa, T.; Kato, M.; Sekine, I.; Hayashi, S. J. Electrochem. Soc. 1995, 142, 2612-2617. (F224) Zen, J.-M.; Jeng, S.-H.; Chen, H.-J. Anal. Chem. 1996, 68, 498502. (F225) Fitch, A.; Du, J. Environ. Sci. Technol. 1995, 30, 12-15. (F226) Joo, P.; Fitch, A.; Park, S.-H. Environ. Sci. Technol. 1997, 31, 2186-2192. (F227) Joo, P.; Fitch, A. Environ. Sci. Technol. 1996, 30, 2681-2686. (F228) Mandler, D.; Turyan, I. Electroanalysis 1996, 8, 207-213. (F229) Kaifer, A. E. Prog. Colloid Polym. Sci. 1997, 103, 193-200. (F230) Kaifer, A. E. Isr. J. Chem. 1997, 36, 389-397. (F231) Fox, M. A.; Wolf, M. O.; Reese, R. S. NATO ASI Ser., Ser. C 1996, 485, 143-162. (F232) Maskus, M.; Tirado, J.; Hudson, J.; Bretz, R.; Abrun ˜a, H. D. NATO ASI Ser., Ser. C 1996, 485, 337-353. (F233) DeArmond, M. K.; Fried, G. A. Prog. Inorg. Chem. 1997, 44, 97-142. (F234) Shimidzu, T.; Iyoda, T.; Segawa, H. Macromol. Symp. 1996, 101, 207-218. (F235) Tur’yan, Y. I. Talanta 1997, 44, 1-13. (F236) Rusling, J. F.; Zhou, D.-l.; Gao, J. Proc.-Electrochem. Soc. 1997, 97-6, 137-149. (F237) Rusling, J. F. Colloids Surf., A 1997, 123, 81-88. (F238) Slowinski, K.; Chamberlain, R. V., II.; Bilewicz, R.; Majda, M. J. Am. Chem. Soc. 1996, 118, 4709-4710. (F239) Bruchner-Lea, C.; Kimmel, R. J.; Janata, J.; Conroy, J. F. T.; Caldwell, K. Electrochim. Acta 1995, 40, 2897-2904.

(F240) Creager, S. E.; Rowe, G. K. J. Electroanal. Chem. 1997, 420, 291-299. (F241) Campbell, D. J.; Herr, B. R.; Hulteen, J. C.; Van Duyne, R. P.; Mirkin, C. A. J. Am. Chem. Soc. 1996, 118, 10211-10219. (F242) Yang, D. F.; Al-Maznai, H.; Morin, M. J. Phys. Chem. B 1997, 101, 1158-1166. (F243) Zhong, C.-J.; Zak, J.; Porter, M. D. J. Electroanal. Chem. 1997, 421, 9-13. (F244) Yang, D. F.; Wilde, C. P.; Morin, M. Langmuir 1997, 13, 243249. (F245) Bretz, R. L.; Abrun ˜a, H. D. J. Electroanal. Chem. 1996, 408, 199-211. (F246) Mo, Y.; Sandifer, M.; Sukenik, C.; Barriga, R. J.; Soriaga, M. P.; Scherson, D. Langmuir 1995, 11, 4626-4628. (F247) Marx-Tibbon, S.; Ben-Dov, I.; Willner, I. J. Am. Chem. Soc. 1996, 118, 4717-4718. (F248) Wolf, M. O.; Fox, M. A. Langmuir 1996, 12, 955-962. (F249) Gao, Z.; Siow, K. S. Electrochim. Acta 1996, 42, 315-321. (F250) Yonemura, H.; Ohishi, K.; Matsuo, T. Chem. Lett. 1996, 661662. (F251) Katz, E.; Lion-Dagan, M.; Willner, I. J. Electroanal. Chem. 1996, 408, 107-112. (F252) Ferrence, G. M.; Henderson, J. I.; Kurth, D. G.; Morgenstern, D. A.; Bein, T.; Kubiak, C. P. Langmuir 1996, 12, 3075-3081. (F253) Zhang, Y.; Li, Q.; Xie, Z.; Hua, B.; Mao, B.; Chen, Y.; Tian, Z. Thin Solid Films 1996, 274, 150-153. (F254) Cavalleri, O.; Gilbert, S. E.; Kern, K. Surf. Sci. 1997, 377, 931936. (F255) Cavalleri, O.; Gilbert, S. E.; Kern, K. Chem. Phys. Lett. 1997, 269, 479-484. (F256) Gilbert, S. E.; Cavalleri, O.; Kern, K. J. Phys. Chem. 1996, 100, 12123-12130. (F257) Green, S. J.; Stokes, J. J.; Hostetler, M. J.; Pietron, J.; Murray, R. W. J. Phys. Chem. B 1997, 101, 2663-2668. (F258) Hostetler, M. J.; Green, S. J.; Stokes, J. J.; Murray, R. W. J. Am. Chem. Soc. 1996, 118, 4212-4213. (F259) Wurm, D. B.; Brittain, S. T.; Kim, Y.-T. Langmuir 1996, 12, 3756-3758. (F260) Willicut, R. J.; McCarley, R. L. Adv. Mater. 1995, 7, 759-762. (F261) Sayre, C. N.; Collard, D. M. Langmuir 1997, 13, 714-722. (F262) Rozsnyai, L. F.; Wrighton, M. S. Langmuir 1995, 11, 39133920. (F263) Kim, T.; Ye, Q.; Sun, L.; Chan, K. C.; Crooks, R. M. Langmuir 1996, 12, 6065-6073. (F264) Dhanabalan, A.; Dabke, R. B.; Kumar, N. P.; Talwar, S. S.; Major, S.; Lal, R.; Contractor, A. Q. Langmuir 1997, 13, 43954400. (F265) Xu, J.-J.; Fang, H.-Q.; Chen, H.-Y. J. Electroanal. Chem. 1997, 426, 139-143. (F266) Thoden van Velzen, E. U.; Engbersen, J. F. J.; de Lange, P. J.; Mahy, J. W. G.; Reinhoudt, D. N. J. Am. Chem. Soc. 1995, 117, 6853-6862. (F267) Taniguchi, T.; Yokoyama, Y.; Miyashita, T. Macromolecules 1997, 30, 3646-3649. (F268) Marsella, M. J.; Carroll, P. J.; Swager, T. M. J. Am. Chem. Soc. 1995, 117, 9832-41. (F269) Kim, T.; Chan, K. C.; Crooks, R. M. J. Am. Chem. Soc. 1997, 119, 189-193. (F270) Goldenberg, L. M.; Andreu, R.; Saviron, M.; Moore, A. J.; Garin, J.; Bryce, M. R.; Petty, M. C. J. Mater. Chem. 1995, 5, 15931599. (F271) Zhang, C.-R.; Yang, K.-Z.; Jin, W.-R. Thin Solid Films 1996, 284-285, 533-536. (F272) Morigaki, K.; Liu, Z.-F.; Hashimoto, K.; Fujishima, A. J. Phys. Chem. 1995, 99, 14771-14777. (F273) Inose, Y.; Moniwa, S.; Aramata, A.; Yamagishi, A.; Kyaw, N. Chem. Commun. 1997, 111-112. (F274) de Villeneuve, C. H.; Pinson, J.; Bernard, M. C.; Allongue, P. J. Phys. Chem. B 1997, 101, 2415-2420. (F275) Bandyopadhyay, K.; Sastry, M.; Paul, V.; Vijayamohanan, K. Langmuir 1997, 13, 866-869. BIOELECTROCHEMISTRY (G1) Malinski, T.; Kubaszewski, E.; Kiechle, F. Methods Neurosci. 1996, 31, 14-33. (G2) Malinski, T.; Mesaros, S.; Tomboulian, P. Methods Enzymol. 1996, 268A, 58-69. (G3) Christodoulou, D.; Kudo, S.; Cook, J. A.; Krishna, M. C.; Miles, A.; Grisham, M. B.; Murugesan, R.; Ford, P. C.; Wink, D. A. Methods Enzymol. 1996, 268A, 69-83. (G4) Gow, A. J.; Thom, S. R.; Brass, C.; Ischiropoulos, H. Microchem. J. 1997, 56, 146-154. (G5) Trevin, S.; Bedioui, F.; Devynck, J. Talanta 1996, 43, 303311. (G6) Ciszewski, A.; Kubaszewski, E.; Lozynski, M. Electroanalysis 1996, 8, 293-295. (G7) Bedioui, F.; Trevin, S.; Albin, V.; Gomez Villegas, M. G.; Devynck, J. Anal. Chim. Acta 1997, 341, 177-185. (G8) Privat, C.; Lantoine, F.; Bedioui, F.; Van Brussel, E. M.; Devynck, J.; Devynck, M. Life Sci. 1997, 61, 1193-1202. (G9) Trevin, S.; Andre, S.; Devynck, J.; Boucher, J. L.; Bedioui, F. Anal. Commun. 1997, 34, 69-71.

Analytical Chemistry, Vol. 70, No. 12, June 15, 1998

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(G10) Yu, A.; Zhang, H.; Chen, H. Anal. Lett. 1997, 30, 1013-1023. (G11) Maskus, M.; Abrun ˜a, H. D. Langmuir 1996, 12, 4455-4462. (G12) Friedemann, M. N.; Robinson, S. W.; Gerhardt, G. A. Anal. Chem. 1996, 68, 2621-2628. (G13) Preik-Steinhoff, H.; Kelm, M. J. Chromatogr. 1996, 685, 348352. (G14) Strauss, J. M.; Krohn, S.; Suempelmann, R.; Schroeder, D.; Barnert, R. Anaesthesia 1996, 51, 151-154. (G15) Nelin, L. D.; Christman, N. T.; Morrisey, J. F.; Dawson, C. A. J. Appl. Physiol. 1996, 81, 1423-1429. (G16) Suzuki, S.; Nakato, T.; Hattori, H.; Kita, H. J. Electroanal. Chem. 1995, 396, 143-150. (G17) Gomez, R.; Rodes, A.; Orts, J. M.; Feliu, J. M.; Perez, J. M. Surf. Sci. 1995, 342, L1104-L1110. (G18) Gomez, R.; Rodes, A.; Perez, J. M.; Feliu, J. M. J. Electroanal. Chem. 1995, 393, 123-129. (G19) Gootzen, J. F. E.; van Hardeveld, R. M.; Visscher, W.; van Santen, R. A.; van Veen, J. A. R. Recl. Trav. Chim. Pays-Bas 1996, 115, 480-485. (G20) Cahill, P. S.; Walker, Q. D.; Finnegan, J. M.; Mickelson, G. E.; Travis, E. R.; Wightman, R. M. Anal. Chem. 1996, 68, 31803186. (G21) Schroeder, T. J.; Borges, R.; Finnegan, J. M.; Pihel, K.; Amatore, C.; Wightman, R. M. Biophys. J. 1996, 70, 10611068. (G22) Welch, S. M.; Justice, J. B., Jr. Neurosci. Lett. 1996, 217, 184188. (G23) Ghindilis, A. L.; Michael, N.; Makower, A. Pharmazie 1995, 50, 599-600. (G24) Zhong, M.; Lunte, S. M. Anal. Chem. 1996, 68, 2488-2493. (G25) Gavin, P. F.; Ewing, A. G. J. Am. Chem. Soc. 1996, 118, 89328936. (G26) Pravda, M.; Bogaert, L.; Sarre, S.; Ebinger, G.; Kauffmann, J.; Michotte, Y. Anal. Chem. 1997, 69, 2354-2361. (G27) Thorre, K.; Pravda, M.; Sarre, S.; Ebinger, G.; Michotte, Y. J. Chromatogr. 1997, 694, 297-303. (G28) Pihel, K.; Walker, Q. D.; Wightman, R. M. Anal. Chem. 1996, 68, 2084-2089. (G29) Liu, Z.; Li, J.; Dong, S.; Wang, E. Anal. Chem. 1996, 68, 24322436. (G30) Pihel, K.; Hsieh, S.; Jorgenson, J. W.; Wightman, R. M. Anal. Chem. 1995, 67, 4514-4521. (G31) Takeuchi, Y.; Matsuo, S.; Nishimura, A.; Yamazoe, I.; Kawase, S.; Sawada, T. Prog. HPLC-HPCE 1997, 6, 247-258. (G32) Simonian, A. L.; Rainina, E. I.; Fitzpatrick, P. F.; Wild, J. R. Biosens. Bioelectron. 1997, 12, 363-371. (G33) Pan, S.; Arnold, M. A. Talanta 1996, 43, 1157-1162. (G34) Cosnier, S.; Innocent, C.; Allien, L.; Poitry, S.; Tsacopoulos, M. Anal. Chem. 1997, 69, 968-971. (G35) Niwa, O.; Torimitsu, K.; Morita, M.; Osborne, P.; Yamamoto, K. Anal. Chem. 1996, 68, 1865-1870. (G36) Sugawara, M.; Hirano, A.; Rehak, M.; Nakanishi, J.; Kawai, K.; Sato, H.; Umezawa, Y. Biosens. Bioelectron. 1997, 12, 425439. (G37) Woodward, J. R.; Spokane, R. B. Am. Biotechnol. Lab. 1997, 15, 82-84. (G38) Mazzei, F.; Botre, F.; Lorenti, G.; Porcelli, F. Anal. Chim. Acta 1996, 328, 41-46. (G39) Xin, Q.; Wightman, R. M. Brain Res. 1997, 776, 126-132. (G40) Niwa, O.; Horiuchi, T.; Morita, M.; Huang, T.; Kissinger, P. T. Anal. Chim. Acta 1996, 318, 167-173. (G41) Kataky, R.; Parker, D. Analyst (Cambridge) 1996, 121, 18291834. (G42) Reynolds, N. C., Jr.; Kissela, B. M.; Fleming, L. H. Electroanalysis 1995, 7, 1177-1181. (G43) Shen, H.; Lada, M. W.; Kennedy, R. T. J. Chromatogr. B 1997, 704, 43. (G44) Ranta, V.; Urtti, A.; Auriola, S. J. Chromatogr. 1997, 766, 8597. (G45) Kilts, C. D.; Knight, D. L.; Nemeroff, C. B. Life Sci. 1996, 59, 911-920. (G46) Khan, G. F. Electroanalysis 1997, 9, 533-536. (G47) Losada, J.; Cuadrado, I.; Moran, M.; Casado, C. M.; Alonso, B.; Barranco, M. Anal. Chim. Acta 1997, 338, 191-198. (G48) Shin, M.-C.; Kim, H.-S. Biosens. Bioelectron. 1996, 11, 161169. (G49) Kenausis, G.; Chen, Q.; Heller, A. Anal. Chem. 1997, 69, 1054-1060. (G50) McGrath, M. J.; Iwuoha, E. I.; Diamond, D.; Smyth, M. R. Biosens. Bioelectron. 1995, 10, 937-943. (G51) Thome-Duret, V.; Reach, G.; Gangnerau, M. N.; Lemonnier, F.; Klein, J. C.; Zhang, Y.; Hu, Yibai; Wilson, G. S. Anal. Chem. 1996, 68, 3822-3826. (G52) Jin, Wen; Bier, F.; Wollenberger, U.; Scheller, F. Biosens. Bioelectron. 1995, 10, 823-829. (G53) Silber, A.; Hampp, N.; Schuhmann, W. Biosens. Bioelectron. 1996, 11, 215-223. (G54) Hedenmo, M.; Narvaez, A.; Dominguez, E.; Katakis, I. Analyst (Cambridge) 1996, 121, 1891-1895. (G55) Sugawara, K.; Yamamoto, F.; Tanaka, S.; Nakamura, H. J. Electroanal. Chem. 1995, 394, 263-265. (G56) Gorski, W.; Kennedy, R. T. J. Electroanal. Chem. 1997, 424, 43. 584R

Analytical Chemistry, Vol. 70, No. 12, June 15, 1998

(G57) Baker, D. A.; Gough, D. A. Anal. Chem. 1996, 68, 12921297. (G58) Cambiaso, A.; Delfino, L.; Grattarola, M.; Verreschi, G.; Ashworth, D.; Maines, A.; Vadgama, P. Sens. Actuators 1996, B33, 203-207. (G59) Hitzmann, B.; Ritzka, A.; Ulber, R.; Scheper, T.; Schuegerl, K. Anal. Chim. Acta 1997, 348, 135-141. (G60) Pariente, F.; Lorenzo, E.; Tobalina, F.; Abrun ˜a, H. D. Anal. Chem. 1995, 67, 3936-3944. (G61) Male, K. B.; Bouvrette, P.; Luong, J. H. T.; Gibbs, B. F. J. Food Sci. 1996, 61, 1012-1016. (G62) Chen, J.; Weber, S. G. Anal. Chem. 1995, 67, 3596-3604. (G63) Marconi, E.; Panfili, G.; Messia, M. C.; Cubadda, R.; Compagnone, D.; Palleschi, G. Anal. Lett. 1996, 29, 1125-1137. (G64) Liu, B.; Cui, Y.; Deng, J. Anal. Lett. 1996, 29, 1497-1515. (G65) Yang, Y.; Mu, S. J. Electroanal. Chem. 1996, 415, 71-77. (G66) Hedenmo, M.; Narvaez, A.; Dominguez, E.; Katakis, I. J. Electroanal. Chem. 1997, 425, 1-11. (G67) Uchiyama, S.; Hasebe, Y.; Tanaka, M. Electroanalysis 1997, 9, 176-178. (G68) Doherty, A. P.; Stanley, M. A.; Vos, J. G. Analyst (Cambridge) 1995, 120, 2371-2376. (G69) Daigle, F.; Leech, D. Anal. Chem. 1997, 69, 4108-4112. (G70) Campanella, L.; Crescentini, G.; D’Onorio, M. G.; Favero, G.; Tomassetti, M. Ann. Chim. (Rome) 1996, 86, 527-538. (G71) Deng, Q.; Dong, S. Analyst (Cambridge) 1996, 121, 19791982. (G72) Bala, C.; Radu, G. L.; Gheorghe, D. E.; Magearu, V. J. Med. Biochem. 1997, 1, 47-54. (G73) Ramanavicius, A.; Laurinavicius, V.; Bimbiris, A.; Meskys, R.; Rudomanskis, R. Biologija 1997, 77-80. (G74) Madaras, M. B.; Buck, R. P. Anal. Chem. 1996, 68, 38323839. (G75) Pariente, F.; Tobalina, F.; Moreno, G.; Hernandez, L.; Lorenzo, E.; Abrun ˜a, H. D. Anal. Chem. 1997, 69, 4065-4075. (G76) Dennison, M. J.; Hall, J. M.; Turner, A. P. F. Analyst (Cambridge) 1996, 121, 1769-1773. (G77) Nikolelis, D.; Siontorou, C. C. Electroanalysis 1996, 8, 907912. (G78) Rathbone, D. A.; Holt, P.; Bruce, N. C.; Lowe, C. R. Ann. N.Y. Acad. Sci. 1996, 782, 534-543. (G79) Zhang, Z.; Lei, C.; Sun, W.; Liu, H.; Deng, J. J. Electroanal. Chem. 1996, 419, 85-91. (G80) Ortiz, G.; Gonzalez, M. C.; Reviejo, A. J.; Pingarron, J. M. Anal. Chem. 1997, 69, 3521-3526. (G81) Ikebukuro, K.; Honda, M.; Nakanishi, K.; Nomura, Y.; Masuda, Y.; Yokohama, K.; Yamauchi, Y.; Karube, I. Electroanalysis 1996, 8, 876-879. (G82) Damgaard, L. R.; Revsbech, N. P. Anal. Chem. 1997, 69, 2262-2267. (G83) Larsen, L. H.; Kjr, T.; Revsbech, N. P. Anal. Chem. 1997, 69, 3527-3531. (G84) Braha, O.; Walker, B.; Cheley, S.; Kasianowicz, J. J.; Song, L.; Gouaux, J. E.; Bayley, H. Chem. Biol. 1997, 4, 497-505. (G85) Hasebe, Y.; Oshima, K.; Takise, O.; Uchiyama, S. Talanta 1995, 42, 2079-2085. (G86) Marzouk, S. A. M.; Cosofret, V. V.; Buck, R. P.; Yang, H.; Cascio, W. E.; Hassan, S. S. M. Anal. Chem. 1997, 69, 26462652. (G87) Yang, L.; Overdorf, G.; Kissinger, P. Curr. Sep. 1997, 16, 1518. (G88) Tatsuma, T.; Tani, K.; Oyama, N.; Yeoh, H. Anal. Chem. 1996, 68, 2946-2950. (G89) Gajovic, N.; Warsinke, A.; Scheller, F. W. J. Chem. Technol. Biotechnol. 1997, 68, 31-36. (G90) Lobo, M. J.; Miranda, A. J.; Lopez-Fonseca, J. M.; Tunon, P. Anal. Chim. Acta 1996, 325, 33-42. (G91) Li, Q.; Zhang, S.; Yu, J. Microchem. J. 1995, 52, 166-173. (G92) Palchetti, I.; Cagnini, A.; Del Carlo, M.; Coppi, C.; Mascini, M.; Turner, A. P. F. Anal. Chim. Acta 1997, 337, 315-321. (G93) Deng, Q.; Guo, Y.; Dong, S. Anal. Chim. Acta 1996, 319, 7177. (G94) Parellada, J.; Dominguez, E.; Fernandez, V. M. Anal. Chim. Acta 1996, 330, 71-77. (G95) Huang, X.; Kok, W. T. J. Chromatogr. 1995, 707, 335-342. (G96) Laurinavicius, V.; Kurtinaitiene, B.; Gureviciene, V.; Boguslavsky, L.; Geng, L.; Skotheim, T. Anal. Chim. Acta 1996, 330, 159-166. (G97) Shen, L.; Yang, L.; Peng, T. J. Sci. Food Agric. 1996, 70, 298302. (G98) Adeloju, S. B.; Shaw, S. J.; Wallace, G. G. Anal. Chim. Acta 1997, 341, 155-160. (G99) Bonazzola, C.; Brust, M.; Calvo, E. J. J. Electroanal. Chem. 1996, 407, 203-207. (G100) Niemz, A.; Imbriglio, J.; Rotello, V. M. J. Am. Chem. Soc. 1997, 119, 887-892. (G101) Birss, V. I.; Guha-Thakurta, S.; McGarvey, C. E.; Quach, S.; Vany´sek, P. J. Electroanal. Chem. 1997, 423, 13-21. (G102) Hirst, J.; Sucheta, A.; Ackrell, B. A. C.; Armstrong, F. A. J. Am. Chem. Soc. 1996, 118, 5031-5038. (G103) Rusling, J. F. Electrochem. Soc. Interface 1997, 6(4), 26-31. (G104) Taniguchi, I. Electrochem. Soc. Interface 1997, 6(4), 34-37. (G105) Bowden, E. F. Electrochem. Soc. Interface 1997, 6(4), 40-44.

(G106) Mabrouk, P. A. Anal. Chem. 1996, 68, 189-191. (G107) Loetzbeyer, T.; Schuhmann, W.; Schmidt, H.-L. Bioelectrochem. Bioenerg. 1997, 42, 1-6. (G108) Zhu, Y.; Li, J.; Dong, S. Chem. Commun. (Cambridge) 1996, (1), 51-52. (G109) Brown, K. R.; Fox, A. P.; Natan, M. J. J. Am. Chem. Soc. 1996, 118, 1154-1157. (G110) Li, G.; Chen, H.; Zhu, D. Anal. Chim. Acta 1996, 319, 275276. (G111) Huang, Z.-X.; Feng, M.; Wang, Y.-H.; Cui, J.; Zou, D.-S. J. Electroanal. Chem. 1996, 416, 31-40. (G112) Terrettaz, S.; Cheng, J.; Miller, C. J.; Guiles, R. D. J. Am. Chem. Soc. 1996, 118, 7857-7858. (G113) Cheng, J.; Miller, C. J. J. Phys. Chem. B 1997, 101, 10581062. (G114) Hanrahan, K.-L.; MacDonald, S. M.; Roscoe, S. G. Electrochim. Acta 1996, 41, 2469-2479. (G115) Battistuzzi, G.; Borsari, M.; Dallari, D.; Lancelotti, I.; Sola, M. Eur. J. Biochem. 1996, 241, 208-214. (G116) Ferri, T.; Poscia, A.; Ascoli, F.; Santucci, R. Biochim. Biophys. Acta 1996, 1298, 102-108. (G117) DeSanctis, G.; Maranesi, A.; Ferri, T.; Poscia, A.; Ascoli, F.; Santucci, R. J. Protein Chem. 1996, 15, 599-606. (G118) Razumas, V.; Larsson, K.; Miezis, Y.; Nylander, T. J. Phys. Chem. 1996, 100, 11766-11774. (G119) Kurusu, F.; Kawahara, N. Y.; Ohno, H. Solid State Ionics 1996, 86-88 (Pt. 1), 337-340. (G120) Ohno, H.; Kurusu, F. Chem. Lett. 1996, 8, 693-694. (G121) Kohzuma, T.; Suzuki, S. Mol. Cryst. Liq. Cryst. Sci. Technol. 1996, 286, 417-422. (G122) Battistuzzi, G.; Bosari, M.; Ferretti, S.; Sola, M.; Soliani, E. Eur. J. Biochem. 1995, 232, 206-213. (G123) Bianco, P.; Haladjian, J. Electrochim. Acta 1996, 42, 587594. (G124) Karlsson, J.-J.; Nielsen, M. F.; Thuesen, M. H.; Ulstrup, J. J. Phys. Chem. B 1997, 101, 2430-2436. (G125) Bianco, P.; Haladjian, J. Electroanalysis 1996, 8, 190-194. (G126) Glenn, J. D. H.; Bowden, E. F. Chem. Lett. 1996, 5, 399-400. (G127) Wang, Y.-H.; Cui, J.; Sun, Y.-L.; Yao, P.; Zhuang, J.-H.; Xie, Y.; Huang, Z.-X. J. Electroanal. Chem. 1997, 428, 39-45. (G128) Seetharaman, R.; White, S. P.; Rivera, M. Biochemistry 1996, 35, 12455-12463. (G129) Sarma, S.; DiGate, R. J.; Goodin, D. B.; Miller, C. J.; Guiles, R. D. Biochemistry 1997, 36, 5658-5668. (G130) Barker, P. D.; Butler, J. L.; de Oliveira, P.; Hill, H. A. O.; Hunt, N. I. Inorg. Chim. Acta 1996, 252, 71-77. (G131) Barker, P. D.; Nerou, E. P.; Cheesman, M. R.; Thomson, A. J.; de Oliveira, P.; Hill, H. A. O. Biochemistry 1996, 35, 1361813626. (G132) Kazlauskaite, J.; Westlake, A. C. G.; Wong, L.-L.; Hill, H. A. O. Chem. Commun. (Cambridge) 1996, 18, 2189-2190. (G133) Estabrook, R. W.; Shet, M. S.; Fisher, C. W.; Jenkins, C. M.; Waterman, M. R. Arch. Biochem. Biophys. 1996, 333, 308315. (G134) Zhang, Z.; Nassar, A.-E. F.; Lu, Z.; Schenkman, J. B.; Rusling, J. F. J. Chem. Soc. 1997, 93, 1769-1774. (G135) Hu, N.; Rusling, J. F. Langmuir, 1997, 13, 4119-4125. (G136) Niu, J.; Guo, Y.; Dong, S. J. Electroanal. Chem. 1995, 399, 41-46. (G137) Huang, Q.; Lu, Z.; Rusling, J. F. Langmuir 1996, 12, 54725480. (G138) Sakurai, T.; Nose, F.; Fujiki, T.; Suzuki, S. Bull. Chem. Soc. Jpn. 1996, 69, 2855-2862. (G139) Kuznetsov, B. A.; Byzova, N. A.; Shumakovich, G. P.; Mazhorova, L. E.; Mutuskin, A. A. Bioelectrochem. Bioenerg. 1996, 40, 249-255. (G140) Kohzuma, T.; Dennison, C.; McFarlane, W.; Nakashima, S.; Kitagawa, T.; Inoue, T.; Kai, Y.; Nishio, N.; Shidara, S.; et al. J. Biol. Chem. 1995, 270, 25733-25738. (G141) Zeng, Q.; Kurtz, D. M.; Scott, R. A. Curr. Sep. 1996, 14, 9092. (G142) Nassar, A.-E. F.; Rusling, J. F.; Tominaga, M.; Yanagimoto, J.; Nakashima, N. J. Electroanal. Chem. 1996, 416, 183-185. (G143) Heering, H. A.; Bulsink, Y. B. M.; Hagen, W. R.; Meyer, T. E. Eur. J. Biochem. 1995, 232, 811-817. (G144) Butt, J. N.; Filipiak, M.; Hagen, W. R. Eur. J. Biochem. 1997, 245, 116-122. (G145) Li, J.; Cheng, G.; Dong, S. J. Electroanal. Chem. 1996, 416, 97-104. (G146) Wang, J.; Cai, X.; Fernandes, J. R.; Grant, D. H.; Ozsoz, M. Anal. Chem. 1997, 69, 4056-4059. (G147) Wang, J.; Cai, X.; Rivas, G.; Shiraishi, H.; Farias, P. A. M.; Dontha, N. Anal. Chem. 1996, 68, 2629-2634. (G148) Wang, J.; Rivas, G.; Cai, X.; Dontha, N.; Shiraishi, H.; Luo, D.; Valera, F. S. Anal. Chim. Acta 1997, 337, 41-48. (G149) Wang, J.; Rivas, G.; Cai, X. Electroanalysis 1997, 9, 395-398. (G150) Wang, J.; Palecek, E.; Nielsen, P. E.; Rivas, G.; Cai, X.; Shiraishi, H.; Dontha, N.; Luo, D.; Farias, P. A. M. J. Am. Chem. Soc. 1996, 118, 7667-7670. (G151) Wang, J.; Rivas, G.; Cai, X.; Chicharro, M.; Parrado, C.; Dontha, N.; Begleiter, A.; Mowat, M.; Palecek, E.; Nielsen, P. E. Anal. Chim. Acta 1997, 334, 111-118.

(G152) Wang, J.; Cai, X.; Tian, B.; Shiraishi, H. Analyst 1996, 121, 965-970. (G153) Cai, X.; Rivas, G.; Shiraishi, H.; Farias, P.; Wang, J.; Tomschik, M.; Jelen, F.; Palecek, E. Anal. Chim. Acta 1997, 344, 6576. (G154) Wang, J.; Rivas, G.; Ozsoz, M.; Grant, D. H.; Cai, X.; Parrado, C. Anal. Chem. 1997, 69, 1457-1460. (G155) Siontorou, C. G.; Brett, A.-M. O.; Nikolelis, D. P. Talanta 1996, 43, 1137-1144. (G156) Ihara, T.; Maruo, Y.; Takenaka, S.; Takagi, M. Nucleic Acids Res. 1996, 24, 4273-4280. (G157) Uto, Y.; Kondo, H.; Abe, M.; Suzuki, T.; Takenaka, S. Anal. Biochem. 1997, 250, 122-124. (G158) Singhal, P.; Kuhr, W. Anal. Chem. 1997, 69, 3552-3557. (G159) Bauer, C. G.; Eremenko, A. V.; Ehrentreich-Foerster, E.; Bier, F. F.; Makower, A.; Halsall, H. B.; Heineman, W. R.; Scheller, F. W. Anal. Chem. 1996, 68, 2453-2458. (G160) Jiang, T.; Halsall, H. B.; Heineman, W. R.; Giersch, T.; Hock, B. J. Agric. Food Chem. 1995, 43, 1098-1104. (G161) Jarbawi, T. B.; Halsall, H. B.; Heineman, W. R. Anal. Chem. 1997, 69, 544A-549A. (G162) Stiene, M.; Bilitewski, U. Analyst (Cambridge)) 1997, 122, 155-159. (G163) DelCarlo, M.; Lionti, I.; Taccini, M.; Cagnini, A.; Mascini, M. Anal. Chim. Acta 1997, 342, 189-197. (G164) Chen, S.-F.; Xu, Y.; Ip, M. P.-C. Clin. Chem. (Washington) 1997, 43, 1459-1461. (G165) Limoges, B.; Degrand, C. Anal. Chem. 1996, 68, 4141-4148. (G166) Rapicault, S.; Limoges, B.; Degrand, C. Anal. Chem. 1996, 68, 930-935. (G167) Rickert, J.; Goepel, W.; Beck, W.; Jung, G.; Heiduschka, P. Biosens. Bioelectron. 1996, 11, 757-768. (G168) Maupas, H.; Soldatkin, A. P.; Martelet, C.; Jaffrezic-Renault, N.; Mandrand, B. J. Electroanal. Chem. 1997, 421, 165-172. (G169) Nikolelis, D. P.; Siontorou, C. G.; Andreou, V. G.; Viras, K. G.; Krull, U. J. Electroanalysis 1995, 7, 1082-1089. (G170) Andreou, V. G.; Nikolelis, D. P.; Tarus, B. Anal. Chim. Acta 1997, 350, 121-127. (G171) Cornell, B. A.; Braach-Maksvytis, V. L. B.; King, L. G.; Osman, P. D. J.; Raguse, B.; Wieczorek, L.; Pace, R. J. Nature 1997, 387, 580-583. CHARACTERIZATION OF REDOX REACTIONS (H1) Ahbala, M.; Hapiot, P.; Houmam, A.; Jouini, M.; Pinson, J.; Save´ant, J.-M. J. Am. Chem. Soc. 1995, 117, 11488-11498. (H2) Medebielle, M.; Oturan, M. A.; Pinson, J.; Save´ant, J.-M. J. Org. Chem. 1996, 61, 1331-1340. (H3) Medebielle, M.; Pinson, J.; Save´ant, J.-M. Electrochim. Acta 1997, 42, 2049-2055. (H4) Andrieux, C. P.; Save´ant, J.-M.; Tallec, A.; Tardivel, R.; Tardy, C. J. Am. Chem. Soc. 1996, 118, 9788-9789. (H5) Andrieux, C. P.; Save´ant, J.-M.; Tallec, A.; Tardivel, R.; Tardy, C. J. Am. Chem. Soc. 1997, 119, 2420-2429. (H6) Andrieux, C. P.; Save´ant, J.-M.; Tardy, C. J. Am. Chem. Soc. 1997, 119, 11546-11547. (H7) Anne, A.; Fraoua, S.; Moiroux, J.; Save´ant, J.-M. J. Am. Chem. Soc. 1996, 118, 3938-3945. (H8) Save´ant, J.-M.; Severin, M.-G.; Isse, A. A. J. Electroanal. Chem. 1995, 399, 157-162. (H9) Save´ant, J.-M.; Severin, M.-G.; Isse, A. A. J. Electroanal. Chem. 1996, 402, 195-201. (H10) Grass, V.; Lexa, D.; Momenteau, M.; Save´ant, J.-M. J. Am. Chem. Soc. 1997, 119, 3536-3542. (H11) Gennaro, A.; Isse, A. A.; Severin, M.; Vianello, E.; Bhugun, I.; Save´ant, J.-M. J. Chem. Soc. A 1996, 92, 3963-3968. (H12) Andersen, M. L.; Wayner, D. D. M. J. Electroanal. Chem. 1996, 412, 53-58. (H13) Andersen, M. L.; Long, W.; Wayner, D. D. M. J. Am. Chem. Soc. 1997, 119, 6590-6595. (H14) Andersen, M. L.; Mathivanan, N.; Wayner, D. D. M. J. Am. Chem. Soc. 1996, 118, 4871-4879. (H15) Mubarak, M. S.; Peters, D. G. J. Electroanal. Chem. 1997, 435, 47. (H16) Mubarak, M. S.; Peters, D. G. J. Electroanal. Chem. 1997, 425, 13. (H17) Mubarak, M. S.; Peters, D. G. J. Electrochem. Soc. 1996, 143, 3833. (H18) Butler, A. L.; Peters, D. G. J. Electrochem. Soc. 1997, 144, 4212. (H19) Dahm, C. E.; Peters, D. G. J. Electroanal. Chem. 1997, 410, 163. (H20) Dahm, C. E.; Peters, D. G. J. Electroanal. Chem. 1997, 402, 91. (H21) Vandeputte, S.; Verboom, E.; Hubin, A.; Vereecken, J. J. Electroanal. Chem. 1995, 397, 249-260. (H22) Gooding, J. J.; Compton, R. G.; Brennan, C. M.; Atherton, J. H. Electroanalysis 1996, 8, 519-523. (H23) Correia dos Santos, M. M.; Simoes Goncalves, M. L.; Romao, J. C. J. Electroanal. Chem. 1996, 413, 97-103. (H24) Martin, R. D.; Unwin, P. R. J. Electroanal. Chem. 1995, 397, 325-329.

Analytical Chemistry, Vol. 70, No. 12, June 15, 1998

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(H25) Steponavicius, A.; Radziuniene, B.; Ivaskevic, E.; Girdauskas, B. Chemija 1996, 2, 48-54. (H26) Lever, A. B. P.; Tse, Y.; Manivannan, V.; Strelets, V. V.; Persaud, L. S. Inorg. Chem. 1996, 35, 725-734. (H27) Kontturi, A.; Kontturi, K.; Murtomaeki, L.; Schiffrin, D. J. J. Electroanal. Chem. 1996, 418, 131-137. (H28) Maletin, Y. A.; Strizhakova, N. G.; Kozachkov, S. G.; Cannon, R. D. J. Electroanal. Chem. 1995, 398, 131-137. (H29) Heyrovsky, M.; Prokopova, B. Collect. Czech. Chem. Commun. 1997, 62, 172-184. (H30) Wittrig, R. E.; Kubiak, C. P. J. Electroanal. Chem. 1995, 393, 75-86. (H31) El-Hallg, I. S.; Ghoneim, M. M. Monatsh. Chem. 1996, 127, 487-494. (H32) Koeslag, M. A.; Baird, M. C.; Lovelace, S.; Geiger, W. E. Organometallics 1996, 15, 3289-3302. (H33) Liu, M.; Su, Y. O. J. Electroanal. Chem. 1997, 426, 197-203. (H34) Cheng, S. C.; Blaine, C. A.; Hill, M. G.; Mann, K. R. Inorg. Chem. 1996, 35, 7704-7708. (H35) D’Souza, F.; Hsieh, Y.; Deviprasad, G. R. J. Electroanal. Chem. 1997, 426, 17-21. (H36) Ahmed, S.; Saha, S. K. Can. J. Chem. 1996, 74, 1896-1902. (H37) Eklund, J. C.; Waller, D. N.; Rebbitt, T. O.; Marken, F.; Compton, R. G. J. Chem. Soc. 1995, 1981-1984. (H38) Guedes da Silva, M. F.; da Silva, J. A.; Frausto da Silva, J. J. R.; Pombeiro, A. J. L.; Amatore, C.; Verpeaux, J. Port. Electrochim. Acta 1995, 13, 315-318. (H39) Crawford, P. W.; Carlos, E.; Ellegood, J. C.; Cheng, C. C.; Dong, Q.; Liu, D. F.; Luo, Y. L. Electrochim. Acta 1996, 41, 23992403. (H40) Oliver, E. W.; Evans, D. H.; Caspar, J. V. J. Electroanal. Chem. 1996, 403, 153-158. (H41) Mueller, R.; Lamberts, L.; Evers, M. J. Electroanal. Chem. 1996, 401, 183-189. (H42) Rossenaar, B. D.; Hartl, F.; Stufkens, D. J.; Amatore, C.; Maisonhaute, E.; Verpeaux, J. Organometallics 1997, 16, 4675-4685. (H43) Prieto, I.; Angulo, M.; Mellado, J. M. R. J. Electroanal. Chem. 1995, 399, 135-139. (H44) Prieto, F.; Rueda, M.; Navarro, I.; Sluyters-Rehbach, M.; Sluyters, J. H. J. Electroanal. Chem. 1996, 405, 1-14. (H45) Amatore, C.; Jutand, A.; Medeiros, M. J.; Mottier, L. J. Electroanal. Chem. 1997, 422, 125-132. (H46) Amatore, C.; Jutand, A.; Mottier, L.; Medeiros, M. J. Port. Electrochim. Acta 1995, 13, 383-387. (H47) Aarnts, M. P.; Hartl, F.; Peelen, K.; Stufkens, D. J.; Amatore, C.; Verpeaux, J. Organometallics 1997, 16, 4686-4695. (H48) Le Floch, P.; Mansuy, S.; Ricard, L.; Mathey, F.; Jutand, A.; Amatore, C. Organometallics 1996, 15, 3267-3274. (H49) Levillain, E.; Gaillard, F.; Leghie, P.; Demortier, A.; Lelieur, J. P. J. Electroanal. Chem. 1997, 420, 167-177. (H50) Ruiz Montoya, M.; Rodriguez Mellado, J. M. J. Electroanal. Chem. 1996, 417, 113-118. (H51) Cservenyak, I.; Kelsall, G. H.; Wang, W. Electrochim. Acta 1996, 41, 573-582. (H52) Demaille, C.; Unwin, P. R.; Bard, A. J. J. Phys. Chem. 1996, 100, 14137-14143. (H53) Hapiot, P.; Neudeck, A.; Pinson, J.; Fulcrand, H.; Neta, P.; Rolando, C. J. Electroanal. Chem. 1996, 405, 169-176. (H54) Ortiz, J. L.; Delgado, J.; Baeza, A.; Gonzalez, I.; Sanabria, R.; Miranda, R. J. Electroanal. Chem. 1996, 411, 103-108. (H55) Preigh, M. J.; Stauffer, M. T.; Lin, F.; Weber, S. G. J. Chem. Soc. 1996, 92, 3991-3996. (H56) Muller, R.; Lamberts, L.; Evers, M. J. Electroanal. Chem. 1996, 417, 35-43. (H57) Abdel-Hamid, R. J. Chem. Soc. 1996, 691-696. (H58) Hecht, M.; Schultz, F. A.; Speiser, B. Inorg. Chem. 1996, 35, 5555-5563. (H59) Eichhorn, E.; Rieker, A.; Speiser, B.; Stahl, H. Inorg. Chem. 1997, 36, 3307-3317. (H60) Villeneuve, N. M.; Schroeder, R. R.; Ochrymowycz, L. A.; Rorabacher, D. B. Inorg. Chem. 1997, 36, 4475-4483. (H61) Meunier-Prest, R.; Gaspard, C.; Laviron, E. J. Electroanal. Chem. 1996, 410, 145-154. (H62) Debad, J. D.; Morris, J. C.; Magnus, P.; Bard, A. J. J. Org. Chem. 1997, 62, 530-537. (H63) Bianchini, C.; Peruzzini, M.; Ceccanti, A.; Laschi, F.; Zanello, P. Inorg. Chim. Acta 1997, 259, 61-70. (H64) Dion, D.; Meunier-Prest, R.; Laviron, E. Acta Chem. Scand. 1997, 51 (Suppl.), 411-417. (H65) Galvin, R. M.; Angulo, M.; Mellado, J. M. R. Electroanalysis 1997, 9, 653-654. (H66) Forlano, P.; Olabe, J. A.; Magallanes, J. F.; Blesa, M. A. Can. J. Chem. 1997, 75, 9-13. (H67) Mathieu, E.; Meunier-Prest, R.; Laviron, E. Electrochim. Acta 1997, 42, 2419-2426. (H68) Kappen, T. G. M. M.; van der Linden, J. G. M.; Roelofsen, A. M.; Bour, J. J.; Schlebos, P. P. J.; Steggerda, J. J. Inorg. Chim. Acta 1996, 245, 133-141. (H69) Bottomley, L. A.; Wojciechowski, P. E.; Holder, G. N. Inorg. Chim. Acta 1997, 255, 149-155. 586R

Analytical Chemistry, Vol. 70, No. 12, June 15, 1998

(H70) Ooyama, D.; Nagao, H.; Kuroda, H.; Satoh, U.; Howell, F. S.; Mukaida, M.; Nagao, H.; Tanaka, K. Bull. Chem. Soc. Jpn. 1996, 69, 1593-1598. (H71) Osella, D.; Ravera, M.; Floriani, C.; Solari, E. J. Organomet. Chem. 1996, 510, 45-50. SPECTROELECTROCHEMISTRY (I1) Niu, J.; Dong, S. Rev. Anal. Chem. 1996, 15, 1-171. (I2) Niki, K.; Vrana, O.; Brabec, V. Bioelectrochem.: Princ. Pract. 1996, 3 (Experimental Techniques in Bioelectrochemistry), 251-286. (I3) Beden, B. Mater. Sci. Forum 1995, 192-194 (Pt. 1, Electrochemical Methods in Corrosion Research V1), 277-290. (I4) Bockris, J. O’M.; Fletcher, S.; Gale, R. J.; Khan, S. U. M.; Mazur, D. J.; Uosaki, K.; Weinberg, N. L. Annu. Rep. Prog. Chem., Sect. C: Phys. Chem. 1996, 92, 23-73. (I5) Korzeniewski, C. Crit. Rev. Anal. Chem. 1997, 27, 81-102. (I6) Iwasita, T., Ed. Electrochim. Acta 1996, 41(5), 160. (I7) Higgins, S. J.; Christensen, P. A.; Hamnett, A. In Electroactive Polymer Electrochemistry; Lyons, M. E. G., Ed.; Plenum: New York, 1996; Vol. 2, Chapter 3. (I8) Lopes, M. I. S.; Proenca, L. Port. Electrochim. Acta 1997, 15, 81-111. (I9) Tadjeddine, A.; Peremans, A. Surf. Sci. 1996, 368, 377-383. (I10) Kautek, W.; Geuss, M.; Sahre, M.; Zhao, P.; Mirwald, S. Surf. Interface Anal. 1997, 25, 548-560. (I11) Mulvaney, P. Langmuir 1996, 12, 788-800. (I12) Balzani, V.; Juris, A.; Venturi, M.; Campagna, S.; Serroni, S. Chem. Rev. 1996, 96, 759-833. (I13) Fujikawa, K.; Feng, L. Dianhuaxue 1996, 2, 241-249. (I14) Fujikawa, K.; Feng, L. Dianhuaxue 1996, 2, 357-362. (I15) Wu, J.; Day, J. B.; Franaszczuk, K.; Montez, B.; Oldfield, E.; Wieckowski, A.; Vuissoz, P.-A.; Ansermet, J.-P. J. Chem. Soc., Faraday Trans. 1997, 93, 1017-1026. (I16) Washington, J.; Kubiak, C. P. Can. J. Chem. 1996, 74, 25032508. (I17) Jones, D. H.; Hinman, A. S. Can. J. Chem. 1996, 74, 14031408. (I18) Ding, Z.; Brevet, P. F. Chem. Commun. (Cambridge) 1997, 2059-2060. (I19) Choy de Martinez, M.; Marquez, O. P.; Marquez, J.; Hahn, F.; Beden, B.; Crouigneau, P.; Rakotondrainibe, A.; Lamy, C. Synth. Met. 1997, 88, 187-196. (I20) Kim, S.; Wang, Z.; Scherson, D. A. J. Phys. Chem. B 1997, 101, 2735-2740. (I21) Gutierrez, C. Mod. Aspects Electrochem. 1996, 28, 61-105. (I22) Feng, Z. Q.; Imabayashi, S.; Kakiuchi, T.; Niki, K. J. Electroanal. Chem. 1996, 408, 15-20. (I23) Wang, R.; Iyoda, T.; Tryk, D. A.; Hashimoto, K.; Fujishima, A. Langmuir 1997, 13, 4644-4651. (I24) Enomoto, T.; Hagiwara, H.; Tryk, D. A.; Liu, Z.-F.; Hashimoto, K.; Fujishima, A. J. Phys. Chem. B 1997, 101, 7422-7427. (I25) Babaei, A.; McQuillan, A. J. J. Phys. Chem. B 1997, 101, 74437447. (I26) Flowers, P. A.; Callender, S.-A. Anal. Chem. 1996, 68, 199202. (I27) Dodson, E. D.; Zhao, X.-J.; Caughey, W. S.; Elliott, C. M. Biochemistry 1996, 35, 444-452. (I28) Gaillard, F.; Levillain, E. J. Electroanal. Chem. 1995, 398, 7787. (I29) Gaillard, F.; Levillain, E.; Dhamelincourt, M.-C.; Dhamelincourt, P.; Lelieur, J. P. J. Raman Spectrosc. 1997, 28, 511-517. (I30) Tam, K. Y.; Wang, R. L.; Lee, C. W.; Compton, R. G. Electroanalysis 1997, 9, 219-224. (I31) Wang, R. L.; Tam, K. Y.; Marken, F.; Compton, R. G. Electroanalysis 1997, 9, 284-287. (I32) Wang, R. L.; Tam, K. Y.; Compton, R. G. J. Electroanal. Chem. 1997, 434, 105-115. (I33) Yan, S. G.; Hupp, J. T. Proc.-Electrochem. Soc. 1996, 96-9 (New Directions in Electroanalytical Chemistry), 53-64. (I34) Yan, S. G.; Hupp, J. T. J. Phys. Chem. 1996, 100, 6867-6870. (I35) Kazanskaya, I.; Lexa, D.; Bruschi, M.; Chottard, G. Biochemistry 1996, 35, 13411-13418. (I36) Malinauskas, A.; Holze, R. Ber. Gunsen-Ges. 1997, 101, 18591864. (I37) Zheng, G. D.; Yan, Y.; Gao, S.; Tong, S. L.; Gao, D.; Zhen, K., Jr. Electrochim. Acta 1996, 41, 177-182. (I38) Zhang, H.-Q.; Lin, X.-Q. Talanta 1997, 44, 2069-2073. (I39) Sawtschenko, L.; Jobst, K.; Neudeck, A.; Dunsch, L. Electrochim. Acta 1996, 41, 123-131. (I40) Sato, Y.; Ye, S.; Haba, T.; Uosaki, K. Langmuir 1996, 12, 27262736. (I41) Best, S. P.; Ciniawsky, S. A.; Humphrey, D. G. J. Chem. Soc., Dalton Trans. 1996, 2945-2949. (I42) Beden, B.; Largeaud, F.; Kokoh, K. B.; Lamy, C. Electrochim. Acta 1996, 41, 701-709. (I43) Marinkovic, N. S.; Calvente, J. J.; Kovacova, Z.; Fawcettt, W. R. J. Electrochem. Soc. 1996, 143, L171-L173. (I44) Zhang, H.-Q.; Lin, X.-Q. J. Electroanal. Chem. 1997, 434, 5559. (I45) Pharr, C. M.; Griffiths, P. R. Anal. Chem. 1997, 69, 46654672.

(I46) Pharr, C. M.; Griffiths, P. R. Anal. Chem. 1997, 69, 46734679. (I47) Osawa, M.; Yoshii, K.; Hibino, Y.-ichi; Nakano, T.; Noda, I. J. Electroanal. Chem. 1997, 426, 11-16. (I48) Dunphy, D. R.; Mendes, S. B.; Saavedra, S.; Armstrong, N. R. Anal. Chem. 1997, 69, 3086-3094. (I49) Kulesza, P. J.; Zamponi, S.; Malik, M. A.; Miecznikowski, K.; Berrettoni, M.; Marassi, R. J. Solid State Electrochem. 1997, 1, 88-93. (I50) Kulesza, P. J.; Malik, M. A.; Denca, A.; Strojek, J. Anal. Chem. 1996, 68, 2442-2446. (I51) Campbell, D. J.; Herr, B. R.; Hulteen, J. C.; Van Duyne, R. P.; Mirkin, C. A. J. Am. Chem. Soc. 1996, 118, 10211-10219. (I52) Wu, L.-L.; Luo, J.; Lin, Z.-H. J. Electroanal. Chem. 1996, 417, 53-58. (I53) Vitols, S. E.; Kumble, R.; Blackwood, M. E., Jr.; Roman, J. S.; Spiro, T. G. J. Phys. Chem. 1996, 100, 4180-4187. (I54) Lin, C.-Y.; Spiro, T. G. Inorg. Chem. 1996, 35, 5237-5243. (I55) Trznadel, M.; Zagorska, M.; Lapkowski, M.; Louarn, G.; Lefrant, S.; Pron, A. J. Chem. Soc., Faraday Trans. 1996, 92, 13871393. (I56) Mosier-Boss, P. A.; Newbery, R.; Szpak, S.; Lieberman, S. H.; Rovang, J. W. Anal. Chem. 1996, 68, 3277-3282. (I57) Brown, G. M.; Hope, G. A. J. Electroanal. Chem. 1995, 397, 293-300. (I58) Luczak, T.; Beltowska-Brzezinska, M.; Bron, M.; Holze, R. Vib. Spectrosc. 1997, 15, 17-25. (I59) Xiao, Y.-J.; Markwell, J. P. Langmuir 1997, 13, 7068-7074. (I60) Tian, Z. Q.; Li, W. H.; Gao, J. S. Appl. Spectrosc. 1996, 50, 1569-1577. (I61) Simpson, L. J.; Melendres, C. A. Electrochim. Acta 1996, 41, 1727-1730. (I62) Simpson, L. J.; Melendres, C. A. J. Electrochem. Soc. 1996, 143, 2146-2152. (I63) Zou, S.; Gomez, R.; Weaver, M. J. Langmuir 1997, 13, 67136721. (I64) Lezna, R. O.; Centeno, S. A. Langmuir 1996, 12, 591-593. (I65) Lezna, R. O.; Centeno, S. A. Langmuir 1996, 12, 4905-4908. (I66) Lee, C.-W.; Eklund, J. C.; Dryfe, R. A. W.; Compton, R. G. Bull. Korean Chem. Soc. 1996, 17, 162-167. (I67) Webster, R. D.; Dryfe, R. A. W.; Eklund, J. C.; Lee, C.-W.; Compton, R. G. J. Electroanal. Chem. 1996, 402, 167-174. (I68) Alden, J. A.; Cooper, J. A.; Hutchinson, F.; Prieto, F.; Compton, R. G. J. Electroanal. Chem. 1997, 432, 63-70. (I69) Kepley, L. J.; Bard, A. J. J. Electrochem. Soc. 1995, 142, 41294138. (I70) Lee, C.; Lee, Y. M.; Moon, M. S.; Park, S. H.; Park, J. W.; Kim, K. G.; Jeon, S.-J. J. Electroanal. Chem. 1996, 416, 139-144. (I71) Lee, C.; Moon, M. S.; Park, J. W. J. Electroanal. Chem. 1996, 407, 161-167. (I72) Mortimer, R. J.; Dillingham, J. L. Proc.-Electrochem. Soc. 1997, 96-24, 3-13. (I73) Lever, A. B. P.; Tse, Y.; Manivannan, V.; Strelets, V. V.; Persaud, L. S. Inorg. Chem. 1996, 35, 725-734. (I74) Hill, M. G.; Bailey, J. A.; Miskowski, V. M.; Gray, H. B. Inorg. Chem. 1996, 35, 4585-4590. (I75) Tolmachev, Y. V.; Wang, Z.; Scherson, D. A. J. Electrochem. Soc. 1996, 143, 3160-3166. (I76) Abrantes, L. M.; Oliveira, M. C.; Correia, J. P.; Bewick, A.; Kalaji, M. J. Chem. Soc., Faraday Trans. 1997, 93, 1119-1125. (I77) Slaterbeck, A. F.; Shi, Y.; Seliskar, C. J.; Ridgway, T. H.; Heineman, W. R. Proc.-Electrochem. Soc. 1997, 97-19 (Chemical and Biological Sensors and Analytical Electrochemical Methods), 50-60. (I78) Shi, Y.; Seliskar, C. J.; Heineman, W. R. Anal. Chem. 1997, 69, 4819-4827. (I79) Johnson, B. J.; Park, S.-M. J. Electrochem. Soc. 1996, 143, 1277-1282. (I80) Malinauskas, A.; Holze, R. Ber. Gunsen-Ges. 1997, 101, 18511858. (I81) Tezuka, Y.; Aoki, K.; Yajima, H.; Ishii, T. J. Electroanal. Chem. 1997, 425, 167-172. (I82) Li, Y. Electrochim. Acta 1996, 41, 203-210. (I83) Simmons, N. J.; Porter, M. D. Anal. Chem. 1997, 69, 28662869. (I84) Niu, J.; Dong, S. Electroanalysis 1995, 7, 1059-1062. (I85) Kirchhoff, J. R. Curr. Sep. 1997, 16, 11-14. (I86) Xie, Q.-J.; Nie, L.-H.; Yao, S.-Z. Anal. Sci. 1997, 13, 453-456. (I87) Fang, Y.-Zhi; Long, D.; Ye, J. Anal. Chim. Acta 1997, 342, 1321. (I88) Shen, Q.; Harata, A.; Sawada, T. Jpn. J. Appl. Phys. Part 1 1996, 35, 2339-2349. (I89) Maness, K. M.; Terrill, R. H.; Meyer, T. J.; Murray, R. W.; Wightman, R. M. J. Am. Chem. Soc. 1996, 118, 10609-10616. (I90) Hanken, D. G.; Corn, R. M. Anal. Chem. 1997, 69, 3665-3673. (I91) Lee, Y. F.; Kirchhoff, J. R.; Berger, R. M.; Gosztola, D. J. Chem. Soc., Dalton Trans. 1995, 3677-3682. (I92) Ding, Z.; Wellington, R. G.; Brevet, P. F.; Girault, H. H. J. Phys. Chem. 1996, 100, 10658-10663. (I93) Knapp, C.; Lecomte, J.-P.; Mesmaeker, A. K.-D.; Orellana, G. J. Photochem. Photobiol., B 1996, 36, 67-76. (I94) Curtis, C. L.; Wightman, R. M. Proc.-Electrochem. Soc. 1996, 96-9 (New Directions in Electroanalytical Chemistry), 26-40.

(I95) Rosenmund, J.; Doblhofer, K. J. Electroanal. Chem. 1995, 396, 77-83. (I96) Pastore, P.; Magno, F.; Collinson, M. M.; Wightman, R. M. J. Electroanal. Chem. 1995, 397, 19-26. (I97) Cooper, E. L.; Madigan, N. A.; Hagan, C. R. S.; Coury, L. A., Jr. Proc.-Electrochem. Soc. 1996, 96-9 (New Directions in Electroanalytical Chemistry), 338-349. (I98) Preston, J. P.; Nieman, T. A. Anal. Chem. 1996, 68, 966-970. (I99) Wilson, R.; Barker, M. H.; Schiffrin, D. J.; Abuknesha, R. Biosens. Bioelectron. 1997, 12, 277-286. (I100) Karatani, H.; Kojima, M.; Minakuchi, H.; Soga, N.; Shizuki, T. Anal. Chim. Acta 1997, 337, 207-215. (I101) Bard, A. J.; Xu, X.-H. Wo Patent 9606946, 1996. (I102) Belash, E. M.; Rozhitskii, N. N. Russ. J. Electrochem. (Transl. of Elektrokhimiya) 1996, 32, 1263-1272. (I103) Debad, J. D.; Morris, J. C.; Magnus, P.; Bard, A. J. J. Org. Chem. 1997, 62, 530-537. (I104) Clark, C. D.; Debad, J. D.; Yonemoto, E. H.; Mallouk, T. E.; Bard, A. J. J. Am. Chem. Soc. 1997, 119, 10525-10531. (I105) Boher, P.; Defranoux, C.; Piel, J. P.; Stehle, J. L.; Suzuki, Y. Proc. SPIE-Int. Soc. Opt. Eng. 1996, 2873 (Polarization Analysis and Applications to Device Technology), 297-300. (I106) de Souza, L. M. M.; Kong, F. P.; McLarnon, F. R.; Muller, R. H. Electrochim. Acta 1997, 42, 1253-1267. (I107) Reipa, V.; Gaigalas, A. K.; Vilker, V. L. Langmuir 1997, 13, 3508-3514. (I108) Chandrasekaran, K.; Hill, M. J.; Hamilton, W. L.; Nguyen, H. V.; Collins, R. W. Polym. Mater. Sci. Eng. 1996, 74, 381-382. (I109) Granito, C. C.; Goldenberg, L. M.; Bryce, M. R.; Monkman, A. P.; Troisi, L.; Pasimeni, L.; Petty, M. C. Langmuir 1996, 12, 472-476. (I110) Noble, B.; Peacock, R. D. Inorg. Chem. 1996, 35, 1616-1620. (I111) Porsch, M.; Sigl-Seifert, G.; Daub, J. Adv. Mater. (Weinheim, Ger.) 1997, 9, 635-639. (I112) Link, T. A.; Hatzfeld, O. M.; Unalkat, P.; Shergill, J. K.; Cammack, R.; Mason, J. R. Biochemistry 1996, 35, 7546-7552. (I113) Yagi, I.; Nakabayashi, S.; Uosaki, K. J. Phys. Chem. B 1997, 101, 7414-7421. (I114) Tadjeddine, A.; Peremans, A.; Le Rille, A.; Zheng, W. Q.; Tadjeddine, M.; Flament, J.-P. J. Chem. Soc., Faraday Trans. 1996, 92, 3823-3828. (I115) Jung, C. C. Proc. SPIE-Int. Soc. Opt. Eng. 1997, 3180 (Third Pacific Northwest Fiber Optic Sensor Workshop, 1997), 2-8. (I116) Jung, C. C.; Saban, S. B.; Yee, S. S.; Darling, R. B. Sens. Actuators 1996, B32, 143-147. (I117) Chinowsky, T. M.; Saban, S. B.; Yee, S. S. Sens. Actuators 1996, B35, 37-43. (I118) Pierrat, O.; Lechat, N.; Bourdillon, C.; Laval, J.-M. Langmuir 1997, 13, 4112-4118. (I119) Mittler-Neher, S.; Spinke, J.; Liley, M.; Nelles, G.; Weisser, M.; Back, R.; Wenz, G.; Knoll, W. Biosens. Bioelectron. 1995, 10, 903-916. (I120) Ung, T.; Giersig, M.; Dunstan, D.; Mulvaney, P. Langmuir 1997, 13, 1773-1782. (I121) Futamata, M. Surf. Sci. 1997, 386, 89-92. (I122) Pennarun, G. I.; Boxall, C.; O’hare, D. Proc.-Electrochem. Soc. 1997, 97-19 (Chemical and Biological Sensors and Analytical Electrochemical Methods), 1039-1051. (I123) Honda, Y.; Song, M.-B.; Ito, M. Chem. Phys. Lett. 1997, 273(3, 4), 141-146. (I124) Petr, A.; Dunsch, L.; Neudeck, A. J. Electroanal. Chem. 1996, 412, 153-158. (I125) Wilgocki, M.; Rybak, W. K. Port. Electrochim. Acta 1995, 13, 211-218. (I126) Kress, L.; Neudeck, A.; Petr, A.; Dunsch, L. J. Electroanal. Chem. 1996, 414, 31-40. (I127) Heilmann, O.; Hornung, F. M.; Kaim, W.; Fiedler, J. J. Chem. Soc., Faraday Trans. 1996, 92, 4233-4238. (I128) Spangler, N. J.; Lindahl, P. A.; Bandarian, V.; Ludden, P. W. J. Biol. Chem. 1996, 271, 7973-7977. (I129) Hilgers, F.; Bruns, W.; Fiedler, J.; Kaim, W. J. Organomet. Chem. 1996, 511, 273-280. (I130) Beden, L.; Crouigneau, P.; Beden, B.; Lamy, C. J. Electroanal. Chem. 1996, 405, 241-243. (I131) Yahnke, M. S.; Rush, B. M.; Reimer, J. A.; Cairns, E. J. J. Am. Chem. Soc. 1996, 118, 12250-12251. (I132) Day, J. B.; Vuissoz, P.-A.; Oldfield, E.; Wieckowski, A.; Ansermet, J.-P. J. Am. Chem. Soc. 1996, 118, 13046-13050. (I133) Terrill, R. H.; Postlethwaite, T. A.; Chen, C.-Hsien; Poon, C.D.; Terzis, A.; Chen, A.; Hutchison, J. E.; Clark, M. R.; Wignall, G.; et al. J. Am. Chem. Soc. 1995, 117, 12537-12548. (I134) Tong, YuY.; Belrose, C.; Wieckowski, A.; Oldfield, E. J. Am. Chem. Soc. 1997, 119, 11709-11710. (I135) Gootzen, J. F. E.; Visscher, W.; van Veen, J. A. R. Langmuir 1996, 12, 5076-5082. (I136) Gootzen, J. F. E.; Wonders, A. H.; Visscher, W.; van Veen, J. A. R. Langmuir 1997, 13, 1659-1667. (I137) Gootzen, J. F. E.; van Hardeveld, R. M.; Visscher, W.; van Santen, R. A.; van Veen, J. A. R. Recl. Trav. Chim. Pays-Bas 1996, 115, 480-485. (I138) Bae, I. T.; Barbour, R. L.; Scherson, D. A. Anal. Chem. 1997, 69, 249-252.

Analytical Chemistry, Vol. 70, No. 12, June 15, 1998

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(I139) Pastor, E.; Rodriguez, J. L.; Castro, C. M.; Gonzalez, S. Port. Electrochim. Acta 1995, 13, 519-523. (I140) Pastor, E.; Castro, C. M.; Rodriguez, J. L.; Gonzalez, S. J. Electroanal. Chem. 1996, 404, 77-88. (I141) Rodriguez, J. L.; Pastor, E.; Schmidt, V. M. J. Phys. Chem. B 1997, 101, 4565-4574. (I142) Schmidt, V. M.; Pastor, E. J. Electroanal. Chem. 1996, 401, 155-161. (I143) Kolbe, D.; Vielstich, W. Electrochim. Acta 1996, 41, 24572460. (I144) Dalmia, A.; Wasmus, S.; Savinell, R. F.; Liu, C. C. J. Electrochem. Soc. 1996, 143, 556-560. (I145) Wang, J.; Wasmus, S.; Savinell, R. F. J. Electrochem. Soc. 1995, 142, 4218-4224. (I146) Weber, M.; Wang, J.-T.; Wasmus, S.; Savinell, R. F. J. Electrochem. Soc. 1996, 143, L158-L160. (I147) Ren, H.; Szpylka, J.; Anderson, L. B. Anal. Chem. 1996, 68, 243-249. (I148) Iwahashi, H.; Ishii, T. J. Chromatogr., A 1997, 773(1 + 2), 2331. (I149) Xu, X.; Lu, W.; Cole, R. B. Anal. Chem. 1996, 68, 4244-4253. (I150) Lu, W.; Xu, X.; Cole, R. B. Anal. Chem. 1997, 69, 2478-2484. (I151) Van Berkel, G. J.; Zhou, F.; Aronson, J. T. Int. J. Mass Spectrom. Ion Processes 1997, 162, 55-67. (I152) Munk, J.; Christensen, P. A.; Hamnett, A.; Skou, E. J. Electroanal. Chem. 1996, 401, 215-222. (I153) Deng, H.; Mao, H.; Liang, B.; Shen, Y.; Lu, Z.; Xu, H. J. Photochem. Photobiol., A 1996, 99, 71-74. (I154) Daolio, S.; Kristof, J.; Mink, J.; De Battisti, A.; Mihaly, J.; Piccirillo, C. Rapid Commun. Mass Spectrom. 1996, 10, 18811886. (I155) El-Behaedi, E.; Buschmann, H. W.; Iwasita, T.; Vielstich, W.; Ghonein, M. M. Russ. J. Electrochem. (Transl. of Elektrokhimiya) 1995, 31, 111-118. (I156) Day, D. A.; Zook, A. L.; Barshick, C. M.; Hess, K. R. Microchem. J. 1997, 55, 208-221. (I157) Hwang, T.-J.; Jiang, S.-J. J. Anal. At. Spectrom. 1996, 11, 353357. (I158) Henke, C.; Steinem, C.; Janshoff, A.; Steffan, G.; Luftmann, H.; Sieber, M.; Galla, H.-J. Anal. Chem. 1996, 68, 3158-3165. INSTRUMENTATION (J1) Kissinger, P. T.; Yang, L.; Bott, A.; Falck, D.; Bruntlett, C. Proc.Electrochem. Soc. 1996, 96-9 (New Directions in Electroanalytical Chemistry), 350-356. (J2) Mueller-Simon, H.; Mergler, K. W. Glass Sci. Technol. (Frankfurt/ Main) 1995, 68, 273-277. (J3) Kneer, E. A.; Raghunath, C.; Mathew, V.; Raghavan, S.; Jeon, J. S. J. Electrochem. Soc. 1997, 144, 3041-3049. (J4) Hsueh, C. C.; Brajter-Toth, A. Anal. Chim. Acta 1996, 321, 209-214. (J5) Heredia-Lopez, F. J.; Gongora-Alfaro, J. L.; Alvarez-Cervera, F. J.; Bata-Garcia, J. L. Rev. Sci. Instrum. 1997, 68, 1879-1885. (J6) Desmond, D.; Lane, B.; Alderman, J.; Hall, G.; Alvarez-Icaza, M.; Garde, A.; Ryan, J.; Barry, L.; Svehla, G. Sens. Actuators 1996, B34, 466-470. (J7) Bund, A.; Dittmann, J.; Lordkipanidze, D.; Schwitzgebel, G. Fresenius’ J. Anal. Chem. 1996, 356, 27-30. (J8) Nawghare, P. M.; Singh, K.; Limaye, S. S. Solid State Ionics 1996, 90, 295-301. (J9) Stastny, M.; Nepozitek, J. Chem. Listy 1996, 90, 527-533. (J10) Bessant, C.; Saini, S. Electroanalysis 1997, 9, 926-931. (J11) Oduoza, C. F.; Fielden, P. R.; Miller, R. M. Lab. Autom. Inf. Manage. 1996, 32, 71-85. (J12) Stojanovic, R. S.; Greenhill, H. B.; Bond, A. M.; Anderson, J. E. Comput. Chem. 1996, 20, 209-218. (J13) Ruan, X.; Su, Y.; Zhou, Y.; Chang, H.; Feng, D. Talanta 1996, 43, 1657-1665. (J14) Ekkad, N.; Huber, C. O. Anal. Chim. Acta 1996, 332, 155160. (J15) Reay, R. J.; Flannery, A. F.; Storment, C. W.; Kouvanes, S. P.; Kovacs, G. T. A. Sens. Actuators 1996, B34, 450-455. (J16) Paeschke, M.; Dietrich, F.; Uhlig, A.; Hintsche, R. Electroanalysis 1996, 8, 891-898. (J17) Sturrock, P. E.; O’Brien, G. E. Anal. Chim. Acta 1996, 324, 135-145. (J18) Hissner, F.; Mattusch, J.; Werner, G. Fresenius’ J. Anal. Chem. 1996, 354, 718-721. (J19) Huang, Y. L.; Foellmer, T. J.; Ang, K. C.; Khoo, S. B.; Yap, M. G. S. Anal. Chim. Acta 1995, 317, 223-232. (J20) Hoffmann, W.; Rapp, R. Sens. Actuators 1996, B34, 471-475. (J21) Matysik, F.-M. J. Chromatogr., A 1996, 742(1+2), 229-234. (J22) Voegel, P. D.; Baldwin, R. P. Electrophoresis 1997, 18, 22672278. (J23) Yee, H.-J.; Park, J.-K.; Kim, S.-T. Sens. Actuators 1996, B34, 490-492. (J24) Yang, S.; Salehi, C.; Atanasov, P.; Wilkins, E. Anal. Lett. 1996, 29, 1081-1097. (J25) Black, J.; Wilkins, M.; Atanasov, P.; Wilkins, E. Sens. Actuators 1996, B31, 147-153. 588R

Analytical Chemistry, Vol. 70, No. 12, June 15, 1998

(J26) Mabuchi, K.; Chinzei, T.; Abe, Y.; Imanishi, K.; Isoyama, T.; Matsuura, H.; Tago, T.; Kouno, A.; Ono, T.; et al. Int. J. Artif. Organs 1997, 20, 37-42. (J27) Wang, J.; Foster, N.; Lu, J.; Larson, D.; Olsen, K.; Zirino, A. Field Screening Methods Hazard. Wastes Toxic Chem., Proc. Int. Symp.; Air and Waste Management Assoc.: Pittsburgh, PA, 1995; Vol. 2, 691-693. (J28) Wang, J. TrAC, Trends Anal. Chem. 1997, 16, 84-88. (J29) Herdan, J.; Feeney, R.; Kounaves, S. P.; Flannery, A. F.; Storment, C. W.; Kovacs, G. T. A.; Darling, R. B. Environ. Sci. Technol. 1998, 32, 131-136. (J30) Schmidt, J. C. Adv. Instrum. Control 1995, 50(Pt. 2), 47-56. (J31) Achterberg, E. P.; Van den Berg, C. M. G. Mar. Pollut. Bull. 1996, 32, 471-479. (J32) Kasatkin, E. V.; Neburchilova, E. B. Russ. J. Electrochem. (Transl. of Elektrokhimiya) 1996, 32, 843-853. (J33) Yoon, B. U.; Cho, K.; Kim, H. Anal. Sci. 1996, 12, 321-326. (J34) Tong, X. Q.; Aindow, M.; Farr, J. P. G. Microsc. Res. Technol. 1996, 34, 87-95. (J35) Bard, A. J.; Fan, F.-R. F.; Mirkin, M. V. In Handbook of Surface Imaging and Visualization; Hubbard, A. T., Ed.; CRC Press: Boca Raton, FL, 1995; pp 667-679. (J36) Schroder, U.; Scholz, F. J. Solid State Electrochem. 1997, 1, 62-67. (J37) Faguy, P. W.; Marinkovic, N. S. Appl. Spectrosc. 1996, 50, 394400. (J38) Zhuang, L.; Lu, J. Dianhuaxue 1996, 2, 250-253. (J39) Cumpson, P. J. J. Vac. Sci. Technol., A 1997, 15, 2407-2412. (J40) Jagner, D.; Wang, Y.; Ma, F. Electroanalysis 1996, 8, 862869. (J41) Easwarakhanthan, T.; Ravelet, S. Meas. Sci. Technol. 1996, 7, 768-775. (J42) Talaie, A.; Boger, Z.; Romagnoli, J. A.; Adeloju, S. B.; Yuan, Y. J. Synth. Met. 1996, 83, 21-26. (J43) Talaie, A.; Romagnoli, J. Iran. Polym. J. 1997, 6, 53-61. (J44) Defernez, M.; Wilson, R. H. Anal. Chem. 1997, 69, 1288-1294. (J45) Sun, B.; Fitch, P. G.; Johns, I. A.; Skyring, G. W. Water Res. 1997, 31, 362-365. (J46) Hesse, A.; Voss, H. Bioforum 1995, 18, 389-90, 393-4, 396. (J47) Voegel, P. D.; Zhou, W.; Baldwin, R. P. Anal. Chem. 1997, 69, 951-957. (J48) Fermier, A. M.; Gostkowski, M. L.; Colon, L. A. Anal. Chem. 1996, 68, 1661-1664. (J49) Colombo, C.; van den Berg, C. M. G.; Daniel, A. Anal. Chim. Acta 1997, 346, 101-111. (J50) Turyan, Y. Y.; Strochkov, E.; Kuselman, I. I.; Shenhar, A. Gb Patent 2296330, 1996. (J51) Iwasaki, Y.; Niwa, O.; Morita, M.; Tabei, H.; Kissinger, P. T. Anal. Chem. 1996, 68, 3797-3800. (J52) Jayaratna, H. G.; Bruntlett, C. S.; Kissinger, P. T. Anal. Chim. Acta 1996, 332, 165-171. (J53) Augelli, M.; Nascimento, V. B.; Pedrotti, J. J.; Gutz, I. G. R.; Angnes, L. Analyst (Cambridge, U.K.) 1997, 122, 843-847. (J54) Lindfors, T.; Lahdesmaki, I.; Ivaska, A. Anal. Lett. 1996, 29, 2257-2267. (J55) Soucaze-Guillous, B.; Kutner, W. Electroanalysis 1997, 9, 3239. (J56) Schroeder, U.; Meyer, B.; Scholz, F. Fresenius’ J. Anal. Chem. 1996, 356, 295-298. (J57) Madaras, M. B.; Popescu, I. C.; Ufer, S.; Buck, R. P. Anal. Chim. Acta 1996, 319, 335-345. (J58) Joseph, J. P.; Oh, S. US Patent 5554269, 1996. (J59) Johnson, K. A.; Kriz, D. Instrum. Sci. Technol. 1997, 25, 2938. (J60) Jaguiro, P. Proc.-Electrochem. Soc. 1997, 97-5 (Microstructures and Microfabricated Systems), 207-213. (J61) Gorecki, J.; Golas, J. Electroanalysis 1996, 8, 630-634. (J62) Yang, Q.; Atanasov, P.; Wilkins, E. Electroanalysis 1997, 9, 1252-1256. (J63) Schindler, W.; Kirschner, J. Rev. Sci. Instrum. 1996, 67, 35783582. (J64) Horiuchi, T.; Niwa, O.; Hoshino, S. Jp Patent 08190939, 1996. (J65) Bradley, P. E.; Landolt, D. J. Electrochem. Soc. 1997, 144, L145-L148. (J66) Bratten, C. D. T.; Cobbold, P. H.; Cooper, J. M. Anal. Chem. 1997, 69, 253-258. (J67) Wilgocki, M.; Rybak, W. K. Port. Electrochim. Acta 1995, 13, 211-218. (J68) Russell, A. E.; Rubasingham, L.; Hagans, P. L.; Ballinger, T. H. Electrochim. Acta 1996, 41, 637-640. (J69) Simmons, N. J.; Porter, M. D. Anal. Chem. 1997, 69, 28662869. (J70) Niu, J.; Dong, S. Electroanalysis 1995, 7, 1059-1062. (J71) Geskes, C.; Heinze, J. J. Electroanal. Chem. 1996, 418, 167173. (J72) Remmers, J. E.; Schultz, S. A.; Wallace, J.; Takeda, R.; Haji, A. Jpn. J. Pharmacol. 1997, 75, 161-169. (J73) Nascimento, V. B.; Augelli, M. A.; Pedrotti, J. J.; Gutz, I. G. R.; Angnes, L. Electroanalysis 1997, 9, 335-339. (J74) Ohtani, M.; Sunagawa, T.; Kuwabata, S.; Yoneyama, H. J. Electroanal. Chem. 1997, 429, 75-80. (J75) Padeste, C.; Kossek, S.; Lehmann, H. W.; Musil, C. R.; Gobrecht, J.; Tiefenauer, L. J. Electrochem. Soc. 1996, 143, 3890-3895.

(J76) Routkevitch, D.; Tager, A. A.; Haruyama, J.; Almawlawi, D.; Moskovits, M.; Xu, J. M. IEEE Trans. Electron Devices 1996, 43, 1646-1658. (J77) Sreenivas, G.; Ang, S. S.; Fritsch, I.; Brown, W. D.; Gerhardt, G. A.; Woodward, D. J. Anal. Chem. 1996, 68, 1858-1864. (J78) Morita, M.; Niwa, O.; Horiuchi, T. Electrochim. Acta 1997, 42, 3177-3183. (J79) Fiaccabrino, G. C.; Tang, X.-M.; Skinner, N.; Rooij, N. F. de; Koudelka-Hep, M. Sens. Actuators 1996, B35, 247-254. (J80) Belmont, C.; Tercier, M.-L.; Buffle, J.; Fiaccabrino, G. C.; Koudelka-Hep, M. Anal. Chim. Acta 1996, 329, 203-214. (J81) Gavin, P. F.; Ewing, A. G. Anal. Chem. 1997, 69, 3838-3845. (J82) Yang, Z.; Sasaki, S.; Karube, I.; Suzuki, H. Anal. Chim. Acta 1997, 357, 41-49. (J83) Bobkowski, R.; Li, Y.; Fedosejevs, R.; Broughton, J. N. Proc. SPIE-Int. Soc. Opt. Eng. 1996, 2723 (Electron-Beam, X-Ray, EUV, and Ion-Beam Submicrometer Lithographies for Manufacturing VI), 393-401. (J84) Bezryadin, A.; Dekker: C. J. Vac. Sci. Technol., B 1997, 15, 793-799. (J85) Tender, L. M.; Worley, R. L.; Fan, H.; Lopez, G. P. Langmuir 1996, 12, 5515-5518. (J86) Pamidi, P. V. A.; Park, D. S.; Wang, J. Polym. Mater. Sci. Eng. 1997, 76, 513-514. (J87) Sampath, S.; Lev, O. J. Electroanal. Chem. 1997, 426, 131137. (J88) Bogdanosvskaya, V. A.; Evstefeeva, Y.; Tarasevich, M. R. Russ. J. Electrochem. (Transl. of Elektrokhimiya) 1997, 33, 137-141. (J89) Kroeger, S.; Turner, A. P. F. Anal. Chim. Acta 1997, 347, 9-18. (J90) Kletenik, Y. B.; Aleksandrova, T. P. J. Anal. Chem. (Transl. of Zh. Anal. Khim.) 1997, 52, 248-252. (J91) Gun, J.; Lev, O. Anal. Lett. 1996, 29, 1933-1938. (J92) Gun, J.; Lev, O. Anal. Chim. Acta 1996, 336, 95-106. (J93) Hart, J. P.; Wring, S. A. TrAC, Trends Anal. Chem. 1997, 16, 89-103. (J94) Gilmartin, M. A. T.; Ewen, R. J.; Hart, J. P. J. Electroanal. Chem. 1996, 401, 127-137.

(J95) Koncki, R.; Mascini, M. Anal. Chim. Acta 1997, 351, 143149. (J96) Radu, C.; Blidaru, E.; Gheorghe, M. Rev. Roum. Chim. 1996, 41, 51-54. (J97) Yu, P.; Dong, S. Anal. Chim. Acta 1996, 330, 167-174. (J98) Khan, G. F. Electroanalysis 1997, 9, 533-536. (J99) Hyland, M.; Zhou, D. M.; Mclaughlin, J. A.; Mcadams, E. T.; Eggins, B. R. In Sens. Their Appl. VIII, Proc. Conf., 8th; Augousti, A. T.; White, N. M., Eds.; Institute of Physics Publishing: Bristol, U.K., 1997; pp 207-212. (J100) Khan, G. F.; Wernet, W. Anal. Chem. 1997, 69, 2682-2687. (J101) McRipley, M. A.; Linsenmeier, R. A. J. Electroanal. Chem. 1996, 414, 235-246. (J102) Cooper, J. B.; Pang, S.; Albin, S.; Zheng, J.; Johnson, R. M. Anal. Chem. 1998, 70, 464-467. (J103) Sun, J. J.; Fang, H. Q.; Chen, H. Y. Chin. Chem. Lett. 1996, 7, 1016-1018. (J104) Schulte, A.; Chow, R. H. Anal. Chem. 1998, 70, 985-990. (J105) Matysik, F.-M. Electrochim. Acta 1997, 42, 3113-3116. (J106) Di Fabrizio, E.; Grella, L.; Gentili, M.; Baciocchi, M.; Mastrogiacomo, L.; Morales, P. Jpn. J. Appl. Phys. Part 2 1997, 36, L70-L72. (J107) Miles, D. T.; Knedlik, A.; Wipf, D. O. Anal. Chem. 1997, 69, 1240-1243. (J108) Demaille, C.; Brust, M.; Tsionsky, M.; Bard, A. J. Anal. Chem. 1997, 69, 2323-2328. (J109) Pennarun, G. I.; Boxall, C.; O’hare, D. Proc.-Electrochem. Soc. 1997, 97-19 (Chemical and Biological Sensors and Analytical Electrochemical Methods), 1039-1051. (J110) Marzouk, S. A. M.; Cosofret, V. V.; Buck, R. P.; Yang, H.; Cascio, W. E.; Hassan, S. S. M. Talanta 1997, 44, 1527-1541. (J111) Tsirlina, G. A.; Petrii, O. A.; Vassiliev, S. Y. Electrochim. Acta 1996, 41, 1887-1890.

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