Anal. Chem. 1988, 60,106R-113R (344) Dubiel, S. M.; Le Caw, G. Europhys. Lett. 1987, 4 , 487-491. (345) Perlow, G. J.; Potzel, W.; Koch, W. HypeMne Interac. 1987, 33, 293-313. (348) Brett, M. E.; Parkln, K. M.; Graham, M.J. J . Efectrochem. SOC.1986, 133, 2031-2035.
(347) Stevens, J. 0 . ; Li, 2.; Allen, L. Hyperfine Interac. 1986, 2 9 , 1495- 1497. (348) Taneja, S. P.; Harchand, K. S.; Raj, D. Proceedings of the SoM State f”slcs SYmpOSiUm ; Pantnagar , 1988 ; Department of Atomic Energy: Bombay, 1987; Vol. 29C, p 205.
Ion-Selective Electrodes Robert L. Solsky
E. I . du Pont de Nemours, Inc., Imaging Systems Department, New James Street, Towanda, Pennsylvania 18848
INTRODUCTION This review focuses on the more significant contributions to the understanding and use of ion-selective electrodes (ISEs).There is a strong interest in this field as over 1400 articles and abstracts were found during the writing of this review which covers the period from January 1986 through December 1987. The major analytical and electrochemical journals were read and a hand search of Chemical Abstracts uncovered the remaining articles. Unlike previous fundamental reviews, this paper will not attempt to list all the pertinent papers on ISEs. Rather, the more interesting works and applications are covered to illustrate examples of the general trends and directions of ISE interests.
BOOKS AND REVIEWS There have been a host of review papers and publications during the time period covered by this fundamental review. It is very useful to include bibliographies such as that provided by Moody and Thomas in 1986 (1)in that they can provide a much more comprehensive listing of the literature than is possible in this short space. A discussion of the history and analytical uses of ISEs has been prepared by Koryta (2)while Cammann reminds us of the pros and cons of potentiometric analysis (3). The more important developments of potentiometric methods, including theory and applications, have been reviewed (4) and comparisons are drawn between the potentiometric and amperometric methods (5,6). Four of the more recently developed sensors were reviewed by considering the fundamental processes that govern electrode response (7) while others focused on the methods that can be used to increase the accuracy and precision of potentiometric measurementa (8). The following paragraphs summarize the reviews that discuss topics found in the remaining five main sections of this fundamental review and are organized accordingly. The response mechanism of the chalcogenide glass electrodes and electrodes based on other oxide glasses has been reviewed in the areas of electron conduction (9) and analytical behavior of membrane materials (IO). The Ruzicka-type solid-state matrix electrodes were reviewed by considering which silver salts, salt mixtures, and substrates could be used for potentiometric analysis ( 1 1 ) . The development of rareearth ISE’s was outlined from construction and materials selection to analytical applications (12). An interesting aper documented the cases of response of solid-state electroles to quarternary ammonium ions (13). Liquid membrane and solvent polymeric ISE publications once again have represented the majority of papers published in this field. Increasingly, authors from the Peoples Republic of China are becoming involved in this area. Both a general review on electrodes based on ion associates and a review of liquid membrane anion-selective electrodes illustrate this (14, 15). Poly(viny1 chloride) remains the most significant support polymer of choice as described by Thomas (16, 17). Four different classes of polymer-based electrodes have been described for conventional ISE construction and use (18). The most frequently used mediators of the solvent polymeric electrode have been the neutral ion-sequestering agents. Crown ethers and other neutral complexin agents have been reviewed from their structurefunctional refationships to their 106 R
analytical applications in solvent polymeric electrodes (19-22). The desi of ligands suitable for ion-complexing agents was discusseEhile illustrat ’ the improved kinetic performance of modified crown etherxrivatives (23). Long carbon-chain ammonium compounds have also been studied and used as selective ion-sequestering agents where the relation of structure and selectivity were discussed (24). Coated-wire electrodes have been shown to be successful extensions of the conventional polymeric electrodes. Freiser and Cunningham have reviewed the principles of operation and construction techniques (25) while Freiser has summerized the practice and applications of coated wire electrodes (26-28). Specific reviews have been written that cover selected liquid membrane and polymeric electrodes for nitrate (29),lithium (30),and sulfate and phosphate (31). Buck and Cosofret discussed the principles and practice of drug sensors based on liquid membrane electrode structures (32). The combination of ion-selective and gas-selective electrodes with nature’s enzymes has proven to be one of the more fruitful areas of academic research as well for analytical applications. Rechnitz has summarized some of the recent developments and outlined the future prospects for their biocatalytic sensors (33, 34). Another extensive review in this ever-developing biosensor area describes potentiometric biosensors as well as these biosensors based on other modes of detection (35)as do two additional works which extend the realm of biosensors to immunochemistry (36, 37). Enzyme electrodes have been reviewed extensively and include discussions of general principles through analytical applications (38-48). The obvious evolution of enzyme electrodes to include designs that are based on the microbes and tissues that yielded the enzymes has been developed (49, 50). Koryta further describes these strategies and reviews the biological principles that govern these electrode’s behavior (51). As more attention is focussed on the development of immunologically sensitive sensors, the establishment of potential differences at both blocked and unblocked interfaces must be understood as Buck describes (52). The use of potentiometric electrodes as detectors for immunoassays was surveyed by Monroe (53, 54) while Rechnitz looks to the future with several strategies for the creation of more novel biosensors (55). Clinical applications of ISEs have always been the crown jewel for analytical chemists. The potential difficulties have led to several setbacks in the commercial acceptance of these devices in routine use (56). However, ISE-based ap lications do continue to gain acceptance through the intro uction of better and more appropriate analyzers (57,58). Progress in the acceptance of these devices will continue and future applications are being discussed (59, 60). Biosensors are especially suited for use in clinical chemistry (61-65)while many of the basic electrodes find use as well (66-69).Ion-selective microelectrodes have found great utility in physiology and biomedical research. There remains certain fundamental obstacles as a discussion of 30 years of microelectrode use attests (70). The specific design of ionophores for liquid membrane rnicroelectrodea was extensivelyreviewed by Simon et al. and describes the requirements for the desired functional properties (71). Many other reviews discuss principles and design while others focus on specific applications (72-77). Finally, I a m recognizing the dissertations that were published during the time period covered by this fundamental
0003-2700/88/0360-106R$O1.50/00 1988 American Chemical Society
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ION-SELECTIVE ELECTRODES
Iating confidence intervals for the unknowns measured.
SOLID-STATE AND GLASS ELECTRODES
review. They include fundamental studies of ISE behavior (78).enzyme and hiocatalytic electrode studies (79-80, potentiometric immunosensor studies (82),and developments that further the clinical applications of ISEs (83, 84).
GENERAL TOPICS The unique feature of ISEs is their ability to sense and respond to changes in ion activities. That they are able to do this in a matter of seconds to minutes bas led a number of researchers to study their dynamic response (85,86). A versatile means to measure response times was described by Lindner et al. (87). A microprocessor-controlledswitched wall jet cell allowed for precise solution changes while monitoring the dynamic response of the membrane under test. Others have shown that the response mechanism can be related to two relaxation effects (SS),electronic energy transfer and ionic energy transfer. Bipolar pulse conductivity measurements and measurements taken after the application of potential pulses have further defined the nature of the potentiometric response mechanism of ISEs (89,W). The determination of transferance numbers of membranes using anion- and cation-selective electrodes has also aided in understanding the behavior of typical electrodes (91). In addition to the electrical phenomenon that govern the response of ISEs, the effects of temperature compensation on the linear response of electrode system must be acknowledged. Midgley describes both the theory of temperature compensation and the analytical performance of electrodes whose response is inherently nonlinear with temperature (92, 93). The inclusion of a reference electrode in the electrochemical circuit typified by the use of ISEs is a required element but often a troublesome bother. This arisea from the need to hold the potential of a half-cell electrode constant so as to allow the sensing electrode dominance in the overall response of the potentiometric circuit to external variations of the ion of interest. The free-flowing,free-diffusiondesign for a reference electrode junction has always been a favorite for trouble-free operation (94). The performance of these freeflowing liquid junctions has been studied by varying the flow rate, turbulence, and geometries to optimize electrode function (95,W). A specific example that illustrates the need for such reference junctions is the determination of pH of poorly buffered, natural waters (97). Another area of difficulty arises from the so-called "suspension effect" when making potentiometric measurements in particle-laden samples (98). More will he said about this later in the Clinical section and the discussion of whole-blood measurements. A variety of novel reference electrode elements have been described that include stainless steel wire in HCI (B), a solid polymer electrolytewith a porous zirconia junction ( Z O O ) , a planar Ag/AgCI reference electrode (IOl), reference electrodes based on ISEs for use in hot, alkaline sulfide solutions (102,103),and a reference element that is useful to -30 "C (104). The various calibration techniques and analytical methods for the application of ISEs have heen discussed thoroughly in many publications. The advent of computer applications in the laboratory have made some of these potentiometric methods even simpler. The standard addition and subtraction methods were emphasized in a discussion of a computer-assisted, iterative solution to lead determinations (105). Nonlinear regression techniques have also been applied when measurements are taken outside the Nemstian response (1%). When work was done outside the linear response region, more data were required and the results were confirmed by calcu-
Much of the literature that has been published over the last two years that deals with solid-state and glass electrodes has been application oriented. As such, only the more significant developments will be discwed here with some examples given of the trends in this area. A theoretical analysis of the response mechanism of solidstate electrodes was developed by using the iodide electrode as a test esse (107). The principles of the diffusion-layer model were explained in relation to two mechanisms of equilibration of the electrode system. Other studies focus on the impedance characteristics of pressed pellet solid-state electrodes (108). Mixtures of silver sulfide and silver iodide were prepared by varying the pressure and temperature during membrane preparation followed by impedance investigation of the hulk membrane. The transport number of silver ion in the silver sulfide membrane electrode also can be shown to he extremely sensitive to the memhrane composition (109). Surface studies of metal sulfide membranes have revealed the nature and extent of interference (110,111). This was accomplished by monitoring the recrystallization of interferent metal sulfides on the grains of silver sulfide that constitute the sensing membrane. I t has also been shown that the anomalous behavior of the silver sulfide electrode a t low concentrations is governed by the excess of silver ion at the membrane surface (112). The conductivity of doped, single crystals of silver halides decreases with increasing numben of vacancies in the cationic sublattice (113). This is a direct result of increasing doping levels of cadmium or mercury and leads to shorter response times. Glass electrodes for sodium and pH have been shown to exhibit poor selectivity immediately after a cation activity change at the electrode surface (114). The selectivity appears to improve as the electrode reaches its equilibrium potential. Further studies pointed to the loss of selectivity as the electrode operated under non-steady-state conditions (115). These conditions are most prevalent for electrode systems used in automated flow instruments where rapid activity changes occur in the presence of interfering cations. Alternate sensing systems have often been discussed to displace electrochemical pH measurement with optical pH measurement. An excellent comparison of the theoretical differences between the optical and electrochemical pH sensors was recently provided by Janata (116). He concludes with detailed discussion and examples that the electrochemical sensors are more suitable for the practical measurement of pH than would the optical-based sensors. A number of chalcogenide glasses have been described for the detection of copper (117, 118). heavy metals (119).and bromide ion (120). Aside from their compositional uniqueness is their resistance to acidic and corrosive media. Most glass electrodes can be severely etched in fluoride solutions. However, corrosion studies of heavy-metal fluoride glasses have identified certain glass compositions that show anion exchange between fluoride ion on the glass surface and hydroxyl ion in contacting solutions (121). This suggests that glass fluoride electrodes are feasible. The single crystal fluoride ISE was examined as to its response time as a function of the membrane wnductivity (122). Increasing levels of calcium fluoride were incorporated into lanthanum fluoride single crystah and the response times were measured and related to the bulk conductivity of the crystal. The fluoride electrode has been used below its linear response region by estimating the background with multiple standard additions ( 2 2 3 ) . The nonlinear portion of the normal response curve is linearized and fluoride can be determined by interpolation, regardless of interferent level or type. The fluoride electrode can also be used for organic analysis by coupling reactions that liberate fluoride ion (124). In this case, fluorodinitrobenzene reacts with amino acids and the kinetic formation of fluoride ion is used to quantitate those amino acids. There have been some unusual and interesting developments in the fabrication of solid-state sensors. Tungsten bronze membrane electrodes display complex response characteristics and respond to cations with greater or lesser selectivities, depending on the solution conditions (125,126). Solid-state electrodes for pH measurements have been deANALYTICAL CHEMISTRY. VOL. 60, NO. 12, JUNE 15, 1988
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ION-SELECTIVE ELECTRODES
T a b l e I. N e u t r a l C a r r i e r s Designed f o r Common Cations ion Li+
H+ Na+
eaZ'
K+
neutral carrier studied ionomycin substituted 14-crown-4 dioxaazelaamides
1,3-bis(8-quinolyloxy)propanederivatives dioxanonane diamide derivatives several polyether amides decylamine derivatives several nonensin derivatives several alkyl calixaryl acetates ETH 129 o-phenylene derivatives 18-crown-6 derivatives
ref 140 141, 142 143 144 145 146 147 148 149
150 151 152 153 154 155
veloped by using single a-zirconium hydrogen phosphate crystals (127) or palladium hydride (128). A phosphate-selective electrode has been constructed by modifying glassy carbon electrodes with bismuth phosphate (129, 130). The electrode predominantly responds to biphosphate anion and at high pH values hydroxide ion interferes. Common anions such as chloride, nitrate, and sulfate also interfere significantly.
POLY(V1NYL CHLORIDE), LIQUID MEMBRANE, AND COATED-WIRE ELECTRODES Liquid membrane electrodes owe their relatively poor utilization to their short lifetimes and deficiencies in the support matrixes that have been used. The introduction of plasticized poly(viny1chloride) (PVC) as a matrix material changed all that. The traditional liquid support matrixes were macroscopic in nature in that they relied on gross wicking action, similar to absorbent paper towels, to present the ion exchanger dissolved in solvent to the external, analytical sample. PVC, on the other hand, acta in a microscopic manner by forming a molecular network into which the exchangerladen solvent permiates. The PVC swells in the presence of these solvents and releases the solvent to the external sample reluctantly, thus presenting us with an attractive ISE configuration. Moody, Saad, and Thomas provide a detailed comparison of various PVCs with other polymeric materials in their glass transition temperature profiles and their response characteristics (131). The electronic properties of PVC have been studied in as much detail as well. Buck and other described high-frequency membrane resistance and dielectric properties and also low-frequency surface-rate and Warburg impedance characteristics of plasticized PVC electrodes (132,133). These studies further clarified the response mechanism of PVC membrane electrodes and revealed dissociated fixed exchange sites within the PVC matrix that contribute to the electrode's response and selectivity. Additional impedance studies also confirm these findings and help to explain the effects of organic salt additives on resistance, dielectric constant, and
selectivity (134,135). The response mechanism of neutralcarrier-based PVC membrane electrodes was confirmed through the use of voltammetric, potentiometric, chronoamperometric, ion transport, and extraction procedures (136). The fixed sites were shown to lead to a Donnan exclusion of anions from the PVC membrane facilitating the cationic selectivity. X-ray fluorescence and radiotracer studies have further defined the relation between the exchange material, solvent, and PVC matrix, as was demonstrated for bariumselective membranes (137). The relationship of plasticizers and ionophoric structures can also be explained by studying the selectivities of a series of electrode membranes using varying combinations of the solvent and plasticizer (138). If there were any disadvantage of using PVC as a support matrix, it would be in its poor adhesion to certain materials that are desired for commercial applications. A series of chemically modified PVCs has been prepared by incorporating increasing levels of functional groups within the PVC itself (139). These modified PVCs display improved adhesion to silicas while retaining their essential selectivity and response characteristics. There have been many stuudies of neutral carriers used for ISE's. Some of the more common ion applications are listed in Table I along with the neutral carrier used. The solvent is the vehicle which allows the neutral carrier mobility within the PVC matrix and both influences and allows the selectivity process to occur. These solvents, or plasticizers, perform their function best when they display high lipophilicity and viscosity (156). Very often, the addition of lipophilic additives accentuates the effect of the solvent alone. This was shown for both carbonate-selective (157) and lithium-selective (158) electrodes when lipophilic salts were added to the solvent. PVC membrane electrodes have also been prepared by using other than conventional electrode components. Namely, plasticized PVC membranes have been cast directly on graphite or carbon using no internal electrolyte solution. Electrodes selective for potassium (159), silver (160), and ionic surfactants (161) were prepared in this manner and represent the technique that others have employed. The coated-wire electrodes are completely analogous in construction technique except that the PVC membrane is cast directly on a thin, metallic conductor. Examples of this type of sensor have been shown for a nitrate eledrode (162),thallium (163),and a sensor using an aluminum wire for cationic dyes (164). There has been a continued growth in the numbers of PVC membrane electrodes that have been prepared for a variety of substances. These electrodes can be prepared by incorporating any of the many ion-exchange or neutral-sequestering agents within a plasticized PVC matrix. Many of these are of natural origin as in the case for the ever-increasingnumbers of antibiotics that which are being isolated. A list representing these sensors is presented in Table I1 which includes the exchanger used and whether the sensor is capable of direct measurement or is used indirectly, i.e., by titration.
GAS-BASED ELECTRODES AND BIOSENSORS Ion-selective electrodes are immensely useful devices in their own right. However, these basic sensors can find additional, exciting applications when coupled with additionally selective
T a b l e 11. Applications of P V C a n d Liquid M e m b r a n e Electrodes species sensed
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exchanger
Mn2+ nitrite
sulfide, borate, or dibenzyldithiocarbamate aquocyanocobalt(II1) hepta(2-phenylethy1)cobyrinate
Hg2+ Hg2+,Ag+
N-(0,O-diisopropylthiophosphory1)thiobenzamide 1,4-dithia-12-crown-4 or 1,4-dithia-15-crown-5
periodate lidocaine phenytoin diquat and paraquat atropine salicylate trimellitic acid thiamine diphenhydramine amino acid enantiomers cimetidine & ranitidine
nitron periodate salts lidocaine reineckate salt tricaprylmethylammonium chloride complex dibenzo-30-crown-10 or tetraphenylborate complex atropinium 5-nitrobarbiturate or atropinium picrolonate ferrimycobactin hexadecyltrimethylammonium trimellitate thiamine tetraphenylborate diphenhydramine tetraphenylborate chiral crown ethers tetrakis(m-chloropheny1)boratesalts
ANALYTICAL CHEMISTRY, VOL. 60, NO. 12, JUNE 15, 1988
mode direct direct direct and titration titration direct direct direct direct direct direct direct direct direct & titration direct direct
ref 165 166 167
168 169 170 171 172 173 174, 175 176 177 178 179 180
ION-SELECTIVE ELECTRODES
agents. These agents can take the form of chemical barriers to screen out or allow only certain molecules to pass. They can also take the form of catalytic materials which convert otherwise undetectable analytes into chemical species that can be sensed. These approaches are often taken singly or in multiple combinations to create unique sensors capable of measuring the most unusual substances. Gas-SensingElectrodes. The analytical applications of gas-sensing membrane electrodes have been recently discussed (181). The most often encountered difficulty in using gas electrodes is their relatively long response times. An interesting aid in the reduction of response times involves the use of an electrical circuit which is designed for the linearization of the frequency response (182).When applied to the operation of a carbon dioxide gas electrode, the response time was said to have decreased by a factor of 33. The dynamic response of this electrode has been described by a differential equation which models the pH changes that occur within the internal filling solution of the gas electrode (183). The more recent applications of the ammonia-selectivegas electrode concept involve the use of acceptor buffer streams which collect the ammonia gas by protonation with ultimate detection by an ammonium ion internal sensor (184). The selection of the gas-permeable membrane and the receiving buffer composition and pH results in optimum sensitivity and selectivity for ammonia gas detection. A study which is also of interest is the determination of response characteristics of the ammonia-gas-sensing electrode in deuterium oxide solutions (185). There were only minor differences seen in response times while overall dynamic response was unaffected. There have been other, more novel gas-sensing electrodes that have been discussed in the recent literature. This first of these is a unique cyanide sensor that operates as a gasselective electrode (186,187).The sample is acidified and the resultant HCN passes through a porous gas-permeable membrane into an aqueous internal filling solution. The internal filling solution is basic and contains silver nitrate. The influx of cyanide reduces the equilibrium concentration of free silver ion which is measured by the internal silver electrode. This change in potential is related to the amount of cyanide in the original sample. Another unusual gas-selective 8ensor responds to amines such as ethylamine, dimethylamine, and others (188). These electrodes were prepared by replacing the internal electrolyte solution of a normal ammonia electrode with the respective amine hydrochloride solution. Response times were long but recoveries were excellent for the determination of these amines. Enzyme Sensors. The diffusion and kinetic theory of the response of potentiometric enzymes electrodes have been studied (189). Michaelis-Menten kinetics were considered in the construction of the model which included effects of diffusion and the ratio of the thickness of the enzyme-active layer to the external membrane layer thickness. Others have proposed an analytical solution to the response of the enzyme-electrode in the presence of pH buffers (190). The design of enzyme electrodes that are based on pH sensors has been studied in terms of local pH effects at the electrode and enzyme interface (191).These effects are combined with the enzyme kinetics to form a model which can be used to predict the steady-state response of the enzyme sensor. The theories associated with enzyme-electrode response were put to the test in a study of urea-sensing electrodes (192).A model was used that incorporated all of the dependent variables and characteristics were calculated to produce optimum response dynamics. These parameters were tested by preparing and using urea enzyme-electrodesin a variety of pHs, buffer types, and electrode configurations. Urea has been measured by using several combinations of potentiometric sensors such as by differential pH (193,I%), hydrogen ion consumption (195), or ammonia production (196). There have been other unique enzyme sensors studied which utilize unusual catalytic agents or sensors. The fluoride electrode has been linked with the glucose oxidase/peroxidase system for the measurement of glucose using organofluorine compounds as the fluoride source (197).Serious interferents were present in the samples that were measured for glucose, thus limiting the usefulness in this particular a plication. An enzyme-electrodefor chloroform has also been Bescribed (198). A specific bacterium was cultured that degraded chloroform to chloride ion. Extraction of the enzyme and immobilization
to the chloride electrode produced a selective sensor for chloroform. As more “artificial” enzymes are created, it was only a matter of time before one was developed that was capable of converting a substrate into an byproduct that could be detected with a potentiometric sensor. An oxalacetate sensor was constructed by using such a synthetic enzyme with a carbon dioxide gas sensor (199). A polyethylenimine derivative catalyzes the decarboxylation of oxalacetate. The sensor displayed a remarkable lifetime of 6 months compared to the traditional oxalacetate decarboxylase based enzyme which had a lifetime of approximately 1 week. Bacterial, Tissue, and Immuno Sensors. There are many instances where the biocatalytic agent need not be isolated from the parent source to prepare a selective electrode. In fact, there are often benefits associated with leaving the enzyme in its natural state where the various cofactors and structures are present that nature intended. Bacterial electrodes have been prepared for a variety of substances using many different ISEs as base detectors. Biosensors for amino acids have been prepared by using the ammonia gas electrode coupled with whole bacteria where the individual enzymes are unstable (200). Sulfate has been determined by using a sulfide-selective electrode coupled with bacteria which converts sulfate into sulfide by a complex series of enzymatic degradations (201).The selectivity of these biosensors can often be modified by the use of enzyme inhibitors or transport inhibitors as was reported for the inhibition of glutamine response of an E. coli based biosensor (202). The use of potentiometric-based microbial sensors was compared with those sensors based on amperometric detection (203). The mode of operation was influenced by the conditions in the test sample (i.e. pH, oxygen content, substrate concentration) which affected the respective base sensor response. Tissues can be used instead of bacteria in an analogous manner to construct biosensors. In one study, oxalate was successfully determined by using a carbon dioxide gas sensing electrode which was coupled with banana skin pulp (204). The most interesting development in this area was the coupling of the antennule structures from blue crabs to potentiometric detectors which respond selectively to amino acids (205). Amino acids and urea were also determined by using a biosensor based on immobilized flower pieces on an ammonia-gas-sensing electrode (206).These electrodes used intact or minced structural elements of carnations and chrysanthemums which displayed differing responses and selectivities depending on the element used. Another example was reported where magnolia petal slices were coupled with an ammonia-gas-sensing electrode to sense L-glutamine and Lasparagine (207). The final category of biologically sensitized electrodes to be discussed deals with those sensor structures which respond specifically and reversibly to immunological agents. Much has been reported in past years on antibody-responding sensors where the antigen is covalently coupled to an ionophore. The function of these electrodes depended on the specific antigen-ionophore conjugate. A thorough investigation has shown that there exists two distinct modalities of antibody response (208).The first is the case where the antigen possesses no ionophoric character and depends on the ionophore for potential generation or perturbation. A second case was demonstrate where the antigen was not directly coupled with an ionophore. Both of these electrode types were illustrated with experiments on antidigoxin, antidinitrophenol, and antiquinidine immunoelectrodes. An immunosensor concept for the determination of anti-IgG antibodies was published as a patent that described a potential-generating film system that was capable of detecting the immune reaction (209).
CLINICAL AND FLOW APPLICATIONS Ion-selective electrodes have always held a special promise for directly measuring analytes of clinical relevance. The application and use of sensors has taken two distinct paths-the first being more traditional by removing samples and making measurements external to the living system and second involvin indwelling sensors. These two approaches will be discussecfby describing electrodes either that are used statically or that are used in flowing systems. Electrodes that are used in flowing stream analyzers find application in a variety of fields and are included here with clinical applications as a great deal of interest is expressed for these systems. ANALYTICAL CHEMISTRY, VOL. 60, NO. 12, JUNE 15, 1988
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ION-SELECTIVE ELECTRODES
Clinical Applications. The performance of ISE’s is foremost in the minds of those seeking to apply these sensors to clinical measurements. The use of potentiometry in medicine was discussed with em hasis placed on accuracy, liquid junction potentials and t eir errors, standards and calibration techniques, and interferents (210). The specific requirements of anion-selective electrodes were presented and the importance of selectivity, response time, lifetime, and stability was outlined (211). Proteins have often been implicated in the erroneous results reported by electrode assays. A detailed study using equilibrium dialysis was performed to define the extent of interference in the activity measurements using varying levels of albumin (212). The electrodes studied included sodium, potassium, calcium, and chloride and much of the discussion centered on the calcium measurements. The results indicated that calcium binding by albumin was not responsible for the errors seen in the measurement of ionized. Others have shown that the most likely discrepancy lies with errors in the liquid junction potential at the reference electrode (213). Many of these roblems have been overcome with the advent of the s e c o n J r t i o n of ionized calcium analyzers which have instille greater confidence in the clinical labs performing these assays (214). The choice of ion exchangers used in the membrane of the calcium-selectiveelectrode also can influence the system performance (215). In this study, it was shown that the ETHlOOl exchanger performed best by titration to a fixed potential while the more traditional organophosphate exchanger performed well using the known subtraction method. Another approach that adequately reports the ionized calcium level involves dilution with TRIS buffer at physiologic pH and ionic strength (216). The effect of interferents was diluted out while the electrode was still functional at the lowered calcium level. Sodium and potassium measurements have continued on with little additional comment on the correlation between potentiometric results and results generated by flame photometric methods. Representative works include measurements on sodium and potassium (229, sodium and lithium (218),and potassium measurements taken during hemodialysis (219). An improved ionophore for sodium electrodes for clinical analyzers has higher lipophilicity and a greater selectivity for sodium over potassium (220). An interesting use of the potassium electrode has been shown for the determination of the time of death (222). The potassium levels in the human pericardial fluid correlated with the time of death to within 0.5-3 h within the first 48 h after death. Other clinical analytes have been measured with ISEs with success. One clinical analyzer was capable of measuring low levels of total carbon dioxide by utilizing the principle of known addition (222). Following calibration of the analyzer, a known amount of bicarbonate was added to the sample and assayed. The contribution of this know amount was then subtracted from the result to effectively linearize the instrument to low levels of total carbon dioxide in the sample. A novel bicarbonate sensor was described which utilized a planar eometry (223). This particular construction was found to fk very suitable for direct measurement of blood samples. The measurement of blood pH has lon been an assayed quantity. A reference method was approvef by the International Federation of Clinical Chemistry in 1986 and describes the technique in detail (224). The method outlines the minimum requirements in instrumentation, reagents, quality control measures, and analytical variability. The measurement of hemoglobin and hematocrit has also been accomplished with ISE’s (225). Hemoglobin was assayed by utilizing its peroxidase activity to cleave fluoride ion from an organofluorine donor compound. The released fluoride was measured with a fluoride-selective electrode. Hematocrit was measured differentially, using a sodium-selectiveelectrode by comparing sodium levels before and after red cell lysis. Microelectrodes. Ion-selective microelectrodes have proven themselves as reliable measurement devices for investigating ionic processes both within and between single cells. As the potentiometric circuit requires both an indicator electrode and a reference electrode, procedures have been described for preparing double-barrel microelectrodes incorporating both of these elements (226). Instead of the normal side-by-sideconfiguration,others have devised microelectrode pairs consisting of concentric capillaries (227). The inner
f:
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Table 111. Ion-Selective Microelectrode Applications
electrode used pH-liquid membrane
system studied
leech neuropile glial cells & retzius neurons pH-glass snail neurons pH-liquid membrane plant cells Ne, K, C1 cultured heart cells pH, Na, K, C1 helix neurons Na-glass epithelial cells Na-glass cardiac Purkinje fibers K-liquid membrane retinal rod cells C1-liquid membrane epithelial cells C1-liquid membrane mouse liver cells Ca-liquid membrane smooth muscle cells Ca-liquid membrane ferret heart muscle cells Ca-liquid membrane mammalian ganglion neurons
ref
236 237 238 239 240 241 242 243 244 245 246 247 248
barrel was fabricated with a triangular capitlary that protruded beyond the outer capillary and the manipulations were made possible by using two different glasses with distinct melting points. Double-barreled liquid membrane potassium microelectrodes were prepared with tip sizes varying from 0.5 to 6.0 km (228, 229). The tip size of these microelectrodes was shown to influence both the selectivity of the electrode response and variations in the magnitude of the electrode response. Small gas-sensing electrodes have also been prepared for carbon dioxide and ammonia (230). These electrodes were used to characterize acid-base transients in the brain during episodes of spreading depression. Many have tried to modify the characteristics of ion-selective microelectrodes through a variety of techniques. An ever-present problem is the extremely high resistance of the resulting sensor. Recently, a valinomycin-based potassium microelectrode has been prepared with relatively low resishce but retaining an exceedingly high selectivity (231). The fabrication of micro- H sensors has been shown to be easier by replacing the g h - l a s e d sensor with a liquid-membranebased sensor (232). This approach obviatea the need for a microforge and even forgoes the glass itself. Epoxy-based, all-solid-state microelectrodeshave been prepared for calcium determination (233). The traditional structure of the microelectrode has even been replaced with a graphite microelectrode that is directly coated with polymeric f i i s containing the ionophore, solvent, and film matrix (234). There has been concern brought to attention recently about the effects of contamination by leached liquid membrane components on the cells being studied (235). Many of the ionophores used for liquid-membrane electrodes destabilize cellular membranes. The effect of the leached ionophore can often perturb the very ionic species being measured. There have been many more examples showing the use of ion-selective microelectrodes for physiologic measurements. These applications are summarized in Table I11 where the electrode type and use are listed. Flow Applications. Ion-selective electrodes are especially well suited for measurement in flowing streams. The characteristics of the dynamic response of electrodes have been discussed in terms of the linear response range, the detection limit, and the electrodes selectivity (249). In many applications the analyte ion is present in the carrier stream which helps the electrode respond in a Nerstian manner (250). The output of the electrode may often oscillate which is usually indicative of flow rate pulsations cause changes in streaming potentials (251). The geometry of the flow channels, flow rate, and injected sample volume all contribute to the overall response of ISE’s used in analytical flow systems (252, 253). A wall-jet design for the flow cell detector for fluoride determinations was shown to be optimal for response time and low detection limit (254). The sample and carrier stream ionic strength, viscosity, and pH adversely influence the response time of the fluoride electrode in these flow injection systems (255). Others have studied buffer type and composition and have proposed an optimal carrier for fluoride analysis (256). Tubular chloride-selective electrodes have been used in continuous flow analysis (257). The sensor was constructed with PVC tubing and silver foil. The dynamics of the system were described and include response times, working range, interferences, stability and sample through-put. Chloride
ION-SELECTIVE ELECTRODES
electrodes have also found application for hydrochloric acid assay of chloro-organic compounds (2591, determinations (258), and detection of halides and pseuodohalides by using a wire-style electrode (260). The selectivity of ISE-based flow analyzers has been improved with the use of flow dialyzer assemblies (261). The detection limits were shown to improve dramatically for nitrites and nitrogen oxides by confi uring the receiving flow stream for maximum transfer of an yte from the sample flow stream. In an additional modification of this concept, a flowing stream analyzer for salicylate was developed (262). In this system a small receiving stream is held static while a larger sample stream is injected and passes through the dialyzer. The analyte is concentrated within the receiving stream which is flushed to the detector after an appropriate trapping time.
s
ACKNOWLEDGMENT
R.L.S.wishes to thank the Imaging Systems Department for their support in providing library and computer facilities during the preparation of the manuscript. LITERATURE CITED
(1) Moody, G. J.; Thomas, J. D. R. Ion-Sel. Electrode Rev. 1986, S(2). 209-265. (2) Koryta, J. Annu. Rev., Mater. Scl. 1986, 76, 13-27. (3) Cammann, K. SLZ Schweiz, Lab. 2. 1987, 44(2), 57-60, 62-64. Chem. Abstr. 1987, 706, 187916. (4) Svehla, G. Anal. Chem. Symp. Ser. w1986, 131-140. (5) Albery, W. J.; Bartlett, P. N.; Cass. A. E. (3.; Craston, D. H.; Haggett, B. G. D. J. Chem. SOC. 1966, 82(4), 1033-1050. (6) Oehme, F. Tech. MM. 1988, 79(9), 403-408. Chem. Abstr. 1987, 706. 11934. (7) Umezawa, Y. Bunsekl Kagaku 1986, 35(7), 559-573. Chem. Abstr. 1986. 705. 145360. (6) Otto, M.; Thomas, J. D. R. Ion-Sel. Electrode Rev. 1986. 8(1), 55-84. (9) Plsarevskll, A. M.; Andreenko. A. V. Fiz. Khim. Stekk, 1986, 72(3), 257-268. Chem. Abstr. 1986, 705, 68858. (10) Vlasov, Y. 0.; Bychkov, E. A. Ion-Sel. Electrode Rev. 1987, 9(1), 5-93. (11) Jovanovlc, V. M.; Jovanovlc, M. S. Ion-Sel. Ebctrw'eRev. 1986, 8(1), 115- 129. (12) Zhang, Y. Fenxi Huaxue 1987, 75(1), 88-94, Chem. Abstr. 1987, 707, 167773. (13) Selg, W. S. J. Appl. Electrochem. 1987, 77(1), 219. (14) Feng, D. Ion-Sel. Electrode Rev. 1987, 9(1), 95-121. (15) Yu. R. Ion-Sel. Electrode Rev. 1986, 8(2), 153-172. (16) Thomas, J. D. R. Anal. Chlm. Acta 1986, 780, 289-297. (17) Thomas, J. D. R. J. Chem. Soc. 1986, 82(4), 1135-1143. (16) Meares, P. NATO ASI Ser., Ser. C 1966, 787, 181-196. (19) Oggenfuss, P.; Morf, W. E.; Oesch, U.; Ammann, D.; Pretsch, E.; Slmon, W. Anal. Chlm. Acta 1986, 780, 299-311. (20) Takagl, M.; Nakamura, H. J. Coord. Chem. 1986, 75(1), 53-82. (21) Klmura, K.; Shono, T. Women 1986, 24(3), 117-30. Chem. Abstr. 1988, 705, 17204. (22) Ogata, T. Kagaku to Seibotsu 1987, 25(9), 598-600. Chem. Abstr. 1087. .- - . , 707. - . 171679 (23) Lockhart, J. C . j . . C h e m . SOC. 1986, 82(4), 1161-1167. (24) Yuan, Q.; Luo. J. Youjl Huaxue 1986, 4 , 312-316. Chem. Absfr. 1987, 706, 130746. (25) Cunnlngham. L.; Frelser, H. ACS S p p . Ser. 1986. 309, 256-270. (26) Cunninghem. L.; Frelser. H. Anal. Chim. Acta 1988, 780, 271-279. (27) Frelser, H. J. Chem. SOC.w1986, 62(4), 1217-1221. (28) Frelser, H. Pure Appl. Chem. 1987, 59(4), 539-544. (29) Kratochvll. V. Cesk. Hyg. 1988, 37(6), 355-360. Chem. Abstr. 1987, 706, 4148. (30) Gadrekpo, V. P. Y.; Moody, 0. J.; Thomas, J. D. R.; Christian, G. D. Ion-Sel. Electrode Rev. 1988. 8(2), 173-207. (31) Midgley, D. Ion-Sel. Electrode Rev. 1988, 8(1), 3-54. (32) Buck, R. P.; Cosofret, V. V. ACS Symp. Ser. 1988, 309, 363-372. (33) Rechnttz, 0. A. Anal. Chim. Acta 1986, 780, 289-297. (34) Rechnltz, G. A. J. Clln. Lab. Anal. 1987, 7(3),308-311. (35) Hall, E. A. H. Enzyme Mlcrob. Technol. 1986, ( l l ) , 651-658. (36) Janata. J. Roc. Electrochem. SOC. 1987, 87-69. (37) Gabtsr. H. CLB Chem. Labor Betr. 1987, 38(2),58-61. Chem. Abstr. ioa7, 106, 148425. (38) Renneberg, R.; Schubert, F.; Scheller, F. Trends Blochem. SOC. 77(5), 2 16-220. (39) Alzawa, M. Bunseki 1986, (5), 311-315. Chem. Abstr. 1986, 705, 75095. (40) Schmldt, H. L.; Kktsteiner-Eberle. R. Naturwissenschaften 1988, 73(6), 314-321. Chem. Abstr. 1988, 705, 75096. (41) Marshman, C. E. Phys. Bull. lS88, 37(7), 296-299. (42) Eflmov. A. S.: Cherewnov, D. S . V o w . Med. Khlm. 1986. 32(5), 124-132. Chem. Abstr.' 1986, 705, 205570. (43) Gatster. H. CLB Chem. Labor Betr. 1986, 37(10). 501-520, 504, 507. Chem. Abstr. 1988, 705. 237422. (44) Schuegerl, K. QBFManogr. Ser. 1966, 9, 77-92. Chem. Abstr. 1987, 706, 98691. (45) Galster, H. CL6 Chem. LaborBefr. 1987, 38(1), 9-11. Chem. Abstr. 1987, 706, 98709.
.
(46) Kobos, R. K. ASAIO Trans. 1986, 32(2), 701-705. (47) Kobos, R. K. Trends Anal. Chem. 1987, 6(1), 6-9. (48) Gullbault, G. G.; Kauffman, J. M. Blotechnol. Appl. Blochem. 1987, 9(2), 95-113. (49) Karube, I. ACS Symp. Ser. 1986, 309, 330-348. (50) Arnold, M. A. Ion-Sel. Electrode Rev. 1986, 8(1),85-113. (51) Koryta, J. Electrochim. Acta 1986, 31(5), 515-520. (52) Buck, R. P. J . Chem. Soc.1986, 82(4), 1169-1178. (53) Monroe, D. Immunoassay Technol. 1986, 2, 57-70. (54) Monroe, D. Am. 6btechnol. Lab. 1986, 4(6), 30-31, 34-39. (55) Rechnitz, G. A. Trends Anal. Chem. 1986, 5(7), 172-174. (56) Russell, L. J.; Rawson. K. M. Biosensors 1986, 2(5), 301-318. (57) Meyerhoff, M. E.; Opdycke, W. N. Adv. Clin. Chem. 1988, 25, 1-47. (58) Nabet, P. Analusis 1987, 75(8), 379-385. Chem. Abstr. 1987, 707, 232354. (59) Oesch, U.; Ammann, D.; Simon, W. Ciin. Chem. 1986, 32(6), 1448-1459. (60) O'Connell, K. M. Proc., Electrochem. SOC. 1986, 86-14, 7-15. (61) Mascini, M.; Guilbault, G. G. Biosensors 1986, 2(3), 147-172. (62) Campanella, L.; Tomassetti, M. Clin. Lab. 1986, 70(2), 109-121. (63) Diamond, D.; Svehla, G. Trends Anal. Chem. 1987, 6(2), 46-49. (64) Alzawa, M. Shikoku Kokenkalho 1987, 38, 3-10. Chem. Abstr. 1987, 107, 150458. (65) Masclnl, M.; Gullbault, G. G. G. Ital. Chim. Clin. 1986, 17(4),241-255. Chem. Abstr. 1987, 707, 194305. (66) Kosaka, A.; Morlshk, Y. Taisha 1986, 23(9), 857-863. Chem. Abstr. 1987, 706, 115858. (67) Gadzekpo, V. P. Y.; Moody, G. J.; Thomas, J. D.R. Port. Electrochim. Acta 1986, 4 , 5-32. Chem. Abstr. 1987, 706, 148760. (68) Parker, D. J. Phys. E.: Sci. Instrum. 1987, 20(9), 1103-1112. (69) Takahashi, K. Med. Technol. 1987, 75(7), 616-619. (70) Hlnke, J. A. M. Can. J. Physlol. Pharmacol. 1987, 65(5), 873-878. (71) Ammann, D.; Oesch, U.; Buehrer; Simon, W. Can. J. Physioi. PharmaCol. 1987, 65(5). 879-884. (72) Ammann, D. Ion-Selective Microelectrodes: principles Des@ and Application; Springer-Verlag: Berlin, Fed. Rep. Ger., 1986; 346 pp. (73) Fabczak. S . Acta Protozool. 1986, 25(3), 315-324. (74) Okada, Y.; Oiki. S. Seitai no Kagaku 1966, 37(4), 404-406. Chem. Abstr. 1987, 706, 80996. (75) Blagl, B. A. Contemp. Issues Nephrol. 1987, 75, 1-18. (76) Levy, S . ; Tlllotson, D. Can. J. Physiol. Pharmacol. 1987, 65(5), 904-914. (77) Alvarez-Leefmans. F. J.; Giraklez, F.; Gamino, S . M. Can. J. Physiol. Pharmacoi. 1987, 65(5), 915-925. (78) Dixon, L. A. Dlss. Abstr., Int. 6 . 1987, 47(11), 4485-4486. Chem. Abstr. 1967, 107, 14591. (79) Bradley, C. R. Diss. Abst., Int. 6 . 1987, 47(9), 3733. Chem. Abstr. 1987, 706, 192070. (80) Nabi Rahni, M. A. Diss. Abstr., Int. 6 1986, 47(4), 1520. Chem. Abstr. 1987, 706, 29409. (81) Smlt, N. J. Diss. Abstr., Int. 6 1986, 47(2), 606. Chem. Abstr. 1987, 706. 15256. (82) Ciawley, C. D. Diss. Abstr., Int. 6 1987, 47(12), 4845. Chem. Abstr. 1987, 107, 75717. (83) Opdycke, W. N. Diss. Abstr., Int. 6 . 1986, 47(3). 1028. Chem. Abstr. 1987. 106. 2503. (84) Xle, Y. S. Diss. Abstr., Int. 6 1987, 47(12), 4851-4852. Chem. Absfr. 1987, 707, 55025. (85) Fujlwara, S.: Hayashl, I.; Saito, Y. Anal. Sci. 1986, 2(1), 87-88. (86) Chang, 0. K. J. Chem. Educ. 1987, 64(1), 91-92. (87) Llndner, E.; Toth, K.; Pungor, E.; Berube, T. R.; Buck, R. P. Anal. Chem. 1987, 59(17), 2213-2216. (68) Fuglwara, S. Pure Appi. Chem. 1987, 59(4), 531-534. (89) Sandifer, J. R.; Gross, S. Anal. Chim. Acta 1987, 192(2), 237-242. (90) Fujiwara, S. Bunseki 1986, (6), 371-378. Chem. Abstr. 1986, 705, 107553. (91) Welngaertner, H.; Braun, B. M.; Schmoll, J. M. J. SoluNon Chem. 1987, 76(6), 419-431. (92) Midgley, D. Analyst 1987, l72(5), 573-579. (93) Mldgley, D. Analyst 1987, 172(5), 581-585. (94) Dohner, R. E.; Wegmann, D.; Morf, W. E.; Simon, W. Anal. Chem. 1986. 58(12), 2585-2589. (95) Harbinson, T. R.; Davison, W. Anal. Chem. 1987, 59(20), 2450-2456. (96) Davison, W.; Harbinson, T. R. Anal. Chim. Acta 1986, 187, 55-65. (97) Mldgley, D. Atmos. Environ. 1987, 27(1), 173-177. (98) Oman, S.; Godec, A. J. Electroanal. Chem. Interfacial Electrochem. 1986, 206(1-2), 349-356. (99) Oniclu, L.; L o w , D. A.; Siber, I. A.; Florea, C. E. Analusis 1987, 75(4), 197-199. Chem. Abstr. 1987, 107, 146368. (100) Hettlarachchi, S.; MacDonald, D. D. J. Electrochem. SOC. 1987, 734 (5), 1307-1308. (101) Burns, I. W.; Nylander, C. I. Anal. Proc. 1986, 23(8), 289-291. (102) Li, H. Analyst 1987, 112(11), 1607-1609. (103) Crowe, D. C.; Tromans, D. Corroslon 1986, 42(7), 409-415. (104) Crowe, D. C.: Tromans, D. Pap. Int. Symp. Corros. Pulp Pap. Ind., 5th 1986, 159-167. Chem. Abstr. 1987, 106, 184862. (105) Weng, Y. J.; Wilds, 8. E. Corrosion 1986, 42(7), 435-436. (106) Ebel, S.; Becht, U. Fres. 2. Anal. Chem. 1987, 327(2), 157-164. (107) Lewenstam, A.; Hulanicki, A.; Sokalski, T. Anal. Chem. 1987, 59(11), 1539-1544. (108) Gratzl, M.; Pungor, E.; Buck, R. P. Anal. Chlm. Acta 1966, 789(2), 217-228. (109) Young, V. Solid State Ionics 1986, 20(4), 277-282. (110) Pal, F.; Toth, K.;Pungor, E.; FarkasJahnke, M.; Ebel. H.; Ebel, M. F. Anal. Chim. Acta 1988, 780, 313-321. ANALYTICAL CHEMISTRY, VOL. 60, NO. 12, JUNE 15, 1988
111 R
ION-SELECTIVE ELECTRODES
(111)Graf Harsanyi, E.; Toth, K.; Pungor, E.; Maria, F. E. Magy. Kem. Foly. 1988, 92(11-12),537-546. Chem. Abstr. 1987, 106,92399. (112) Graf Harsanyi, E.; Toth, K.; Pungor, E. Magy. Kem. Foly. 1988, 92(11-12).545-551. Chem. Abstr. 1987, 106,92400. (113) Vlasov, Y. G.; Ermolenko, Y. E.; Nikoiaev, 8. A. Zh. Anal. Khim. 1986, 41(7),1192-1195. Chem. Abstr. 1986, 105, 122801. (114) Arnold, M. A,; Zlsman. S. A. Anal. Chim. Acta 1988, 787, 17-29. (115) Wangsa, J.; Arnold. M. A. Anal. Chem. 1987, 59(13),1604-1608. (116) Janata, J. Anal. Chem. 1987, 59(9). 1351-1356. (117) Vlasov. Y. G.; Bychkov, E. A.; Medvedev, A. M. Anal. Chlm. Acta 1986, 185, 137-156. (118) Viasov, Y. G.; Bychkov, E. A.; Medvedev, A. M. Ionnyi Obmen Ionomettyia 198St5 , 130-149. Chem. Abstr. 1987, 106,167877. (119) Tohge, N.; Tanaka, M. J. Non-Cryst. SolMs 1988, 80(1-3),550-556. (120) Golikov, D. V.; Viasov, Y. G.; Bychkov. E. A.: Moskvin, L. N. Zh. Anal. Khim. 1988,41(9),1635-1640. Chem. Abstr. 1987, 106,60405. (121) Ravaine. D.; Perera, G. J . Am. Ceram. SOC.1988,69(12),852-857. (122) Vlasov. Y. G.; Ermolenko, Y. E.; Nikolaev, B. A,; Chernov, S.V. Zh. Prikl. Khim. 1988. 59(8), 1874-1876. Chem. Abstr. 1988, 105, 160731. (123) Smid, J. R.; Kruger, B. J. Analyst 1988, 1 1 1(4),467-470. (124) Athanasiou-Malaki, E.; Koupparis, M. A. Analyst 1987, 112(6), 757-761. (125) Dobson. J. V.; Comer, J. J . Electroanal. Chem. Interfacial Electrochem. 1987, 220(2),225-234. (126) Tadano, H.; Fukazawa, S.; Ichimura, Y.; Kato, N.; Fujleda, S.; Nakano, K. Denki Kagaku oyobi Kogyo Butsurl Kagaku 1987, 55(4), 317-322. Chem. Abstr. 1987, 107,66461. (127) Paiombari, R.; Casciola, M. J . Electroanal. Chem, Interfacial Electrochem. 1987, 216(1-2),283-286. (128) Klhara, S.:Yoshida, 2 . ; Matsui, M. Bull. inst. Chem. Res. Kyoto Univ. 1986, 64(4),207-217. Chem. Abstr. 1987, 106,226459. (129) Grabner, E. W. Chem. Ind. 1986,(9),806-808. (130) Grabner, E. W.; Vermes, I.; Koenig, K. H. J . Electroanal. Chem. I n terfacial Electrochem. 1986,214(1-2),135-140. (131) Moody, G. J.; Saad. B.; Thomas, J. D. R. Analyst 1987, 112(8), 1 143-1 147. (132) Horvai, G.; Graf. E.; Toth, K.; Pungor, E.; Buck, R. P. Anal. Chem. 1986, 58(13),2735-2740. (133) Toth, K.; Graf, E.; Horvai, G.; Pungor, E.; Buck, R. P. Anal. Chem. 1988, 58(13).2741-2744. (134) Horvai, G.; Toth, K.; Pungor, E.; Buck, R. P. Magy. Kem. Foly. 1988, 92(8).364-369. Chem. Abstr. 1987, 106,109828. (135) Horvai, G.; Toth, K.; Graf Harsanyi, E.; Pungor, E. Magy. Kem. foly. 1988, 92(8),370-372. Chem. Abstr. 1987, 706,109829. (136) Morf, W. E.; Slmon, W. Helv. Chlm. Acta 1988, 60(7), 1721-1725. (137) Alexander, P. H.; Moody, G. J.; Thomas, J. D. R.; Birch, B. J. Analyst 1987, 112(6),849-854. (138) Zhou, 2. N.: Xie, R. Y.; Christian, G. D. Anal. Lett. 1988, 19(17-le), 1747-1757. (139) Satchwili, T.; Harrison, D. J. J . Electroanal. Chem. Interfacial Electrochem. 1986, 202(1-2),75-81. (140) Suzuki. K.;Tohda, K.; Tominaga, M.; Tatsuta, K.; Shirai. T. Anal. Lett. 1987,20(6),927-935. (141) Kimura, K.; Yano, H.; Kitazawa, S.;Shono, T. J . Chem. SOC.,Perkin Trans. 2 1986. (12).1945-1951. (142) Kimura, K.; Oishi, H.; Miura. T.; Shono, T. Anal. Chem. 1987,59(19), 2331-2334. (143) Metzger, E.; Aeschimann, R.; Egii, M.; Suter, G.; Dohner, R.; Ammann, D.; Dobier, M.; Simon, W. Helv. Chim. Acta 1986, 69(8), 1821-1828. (144) Hiratani, K.; Okada, T.; Sugihara. H. Anal. Chem. 1987, 59(5), 766-769. (145) Xie, R. Y.; Gadzekpo, V. P. Y.; Kadry. A. M.; Ibrahim, Y. A,; Ruzicka, J.; Christian, G. D. Anal. Chim. Acta 1988, 184,259-269 (146) Gadzekpo, V. P. Y.; Hugerford, J. M.; Kadry, A. M.; Ibrahim, Y. A,; Xie, R. Y.; Christian, G. D. Anal. Chem. 1988, 58(9),1948-1953. (147) Sugihara, H.; Okada, T.; Hiratani, K. Anal. Chim. Acta 1986, 182. 275-280. (148) Wu, H. L.; Yu, R. Talanta 1987, 34(6),577-579. (149) Oesch, U.; Brzozka, 2.; Xu, A.; Rusterholz, B.; Suter, G.; Pham Hung, Viet; Weiti, D.; Ammann, D.; Pretsch, E.; Simon, W. Anal. Chem. 58(11), 2285-2289. (150) Schindier, J. G.; Schindler, M. M. Biomed. Tech. 1987, 32(1-2), 22-24. (151) Bongardt, F.; Voegtie, F.; Wegmann, D.; Ammann, D.; Maruizumi, T.; Simon, W. Helv. Chim. Acta 1987, 70(1),153-157. (152) Diamond, D. Anal. Chem. Symp. Ser. 1986, No. 25, 155-161. (153) Schefer, U.; Ammann, D.; Pretsch, E.; Oesch, U.; Simon, W. Anal. Chem. 1986,58(11),2282-2285. (154) Okada, T.: Sugihara, H.; Hiratani, K. Anal. Chim. Acta 1988, 186. 307-31 1 (155) Rani, A.; Kumar, S.;Bannerjee, N. R. Fres. 2 . Anal. Chem. 1987, 328(1-2),33-36. (156) Oesch, U.; Xu, A.; Brzozka, Z.; Suter, G.; Simon, W. Chimia 1986, 40(10),351-353. (157) Meverhoff, M. E.; Pretsch. E.; Welti. D. H.; Simon, W. Anal. Chem. 1987, 59(l),144-150. (158) Okada, T.; Hiratani, K.; Sugihara, H. Analyst 1987, 112(5).587-593. (159) Xi, 2.; Huang, S.; Zhang, D.: Li. H. fenxi Huaxue 1988, 14(2), 102-106. Chem. Abstr. 1986. 105,53595. (160) Xi, Z.; Li, J.; Yu, L.; Zhang, D.; Yang, J.; Luo, J.; Wu, B.; Cun, L. Huaxue Xuebao 1988, 44(9), 951-954. Chem. Abstr. 1988, 105, 237485. (161)Dowie, C.J.; Cooksey, B. G.; Ottaway, J. M.; Campbell, W. C. Analyst 1987, 112(9),1299-1302. ll2R
ANALYTICAL CHEMISTRY, VOL. 60, NO. 12, JUNE 15, 1988
(162) Lee, Y. K.; Park, J. T.; Kim, C. K.; Whang, K. J. Anal. Chem. 1986, 59(8),2101-2 103. (163) Sanchez-Pedreno, C.; Ortuno, J. A.; Torreciiias, M. C. Analyst 1986, 17 lf121. 1359-1361. (164) V+as, K.; Kaderabkova, M. Chem. Prum. 1986, 36(3), 137-141. Chem. Abstr. 1988, 705, 7926. (165) Motonaka, J.; Nishloka, H.; Ikeda, S.;Tanaka, N. Bull. Chem. Soc. Jpn. 1986,59(1),39-42. Chern. Abstr. 1986, 105,71627. (166) Stepanek, R.; Kraeutler, 8.; Schulthess, P.; Lindemann, B.; Ammann, D.; Simon, W. Anal. Chlm. Acta 1988, 182,83-90. (167) Szczepaniak, W.; Olesky, J. Anal. Chim. Acta 1988, 189(2), 237-243. (168) Lai, M. T.; Shih, J. S.Analyst 1988, 717(8),891-895. (169) Hassan, S. S. M.; Eisaied, M. M. Analyst 1987, 112(4),545-548. (170) Hassan, S. S.M.; Ahmed, M. A. J . Assoc. Off. Anal. Chem. 1988, 69(4),618-620. (171) Cosofret, V. V.; Buck, R. P. J . Pharm. Biomed. Anal. 1986, 4(1). 45-5 1. (172) Moody, G. J.; Owusu, R. K.; Thomas, J. D. R. Analyst 1987, 172(2), 121-127. (173) Hassan, S. S. M.; Ahrned, M. A.; Tadros, F. S. Talanta 1987, 34(8), 723-727. (174) Midgley, D. Anal. Chim. Acta 1988, 182,91-101. (175) Midgley, D. J . Chem. SOC. 1988, 82(4), 1187-1193. (176) Nashed, N. E.; Linderbaum, S.Analyst 1987, 112(2),205-207. (177) Wang, C.; Guo, Y. Microchem. J . 1987,35(3),369-372. (178) Shoukry, A. F.; Badawy, S. S.; Issa, Y. M. J . Electroanal. Chem. Interfacial Nectrochem . 1987,233(1-2),29-36. (179) Shlnbo, T.; Yamaguchi. T.; Nishimura, K.; Kikkawa, M.; Sugiura, M. Anal. Chim. Acta 1987, 793,367-371. (180) Mitsana-Papazoglou, A.; Diamandis, E. F.; Hadjiioannou, T. P. J . Pharm. Sci. 1987, 76(6),485-491. (181) Bruckenstein, S.: Symanski, J. S. J . Chem. Soc. 1988, 82(4), 1105-1 116. (182) Mueckenhoff, K.; Luttmann, A.; Scheid, P. NTG-Fachber. 1988, 93, 47-53. Chem. Abstr. 1988, 105,32635. (183) Livansky, K. Collect. Czech. Chem. Commun. 1987,52(3),582-586. (184) Pranitis, D. M.; Meyerhoff, M. E. Anal. Chem. 1987, 59(19), 2345-2350. (185) Collison, M. E.; Arnold, M. A. Anal. Left.1986, 79(17-la),1759-1776. (186) Opekar, F. Anal. Chim. Acta 1986. 183,293-299. (187) Gratzl, M.; Fligier, J.; Pungor, E. Anal. Scl. 1988, 2(4),331-334. (188) Tagami, S.;Mori, Y.; Matsuura, C. Bunseki Kagaku 1988, 35(9), 814-818. Chem. Abstr. 1986, 705,232529. (189) Sorochlnskil, V. V.; Kurganov, B. I.Zh. Anal. Khim. 1988, 41(11), 2055-2063. Chem. Abstr, 1987. 106,167852. (190) Eddowes, M. J. Sens. Actuators 1987, 11(3),265-274. (191) Varanasi, S.;Stevens, R. L.; Ruckenstein, E. AIChE J . 1987, 33(4), 558-572. (192) Moynihan, H. J.; Wang, N. H. L. Biotechnol. Prog. 1987,3(2),90-100. (193) Kulys, J. J.; Gureviciene, V. V.; Laurinavicius, V. A,; Jonuska, A. V. Biosensors 1988,2(1),35-44. (194) Hamann, H.; Kuehn, M.; Boettcher, N.; Scheiier, F. J . Electroanal. Chem. interfacial Electrochem. 1988,209(l),69-76. (195) Vadgama, P. Analyst 1986, 111(8),875-878. (196) Hsiue, G. H.; Chou, 2 . S.;Yu, N.; Hsiung. K. P. J . Appl. Polm. Sci. 1987, 34(1),319-335. (197) Cowell, D. C.; Ford, P. A. E. Clin. Chem. 1987, 33(8),1458-1460. (198) Rahni, M. A. N.; Kwn, S.S.;Guilbauit, G. G. Enzyme Microb. Techno/. 1988, 8(5),300-304. (199) Ho, M. Y. K.; Rechnitz, G. A. Anal. Chem. 1987, 59(3),536-537. (200) Vincke, B. J.; Vire. J. C.; Patriarche, G. J. Anal. Chem. Symp. Ser. 1988,No. 25, 147-154. (201) Kobos, R. K. Anal. Lett. 1988, 19(3-4),353-362. (202) Corcoran, C. A.; Kobos, R. K. Biotechnol. BlOeng. 1987, 30(4), 565-570. (203) Mascini, M.; Memoii, A. Anal. Chim. Acta 1988, 182,113-122. (204) Fonong, T. Anal. Chim. Acta 1988, 786,301-305. (205) Belli, S.L.; Rechnitz, G. A. Anal. Lett. 1988, 19(3-4),403-416. (206) Uchiyarna, S.;Rechnitz, G. A. Anal. Lett. 1987,20(3),451-470. (207) Uchiyama, S.;Rechnitz, G. A. J . Electroanal. Chem, Interfaclal Electrochem. 1987, 222(1-2),343-346. (208) Bush, D. L.; Rechnitz, G. A. J . Membr. Sci. 1987, 30(3),313-322. (209) Taniguchi, I.; Yasukouchi, K.; Tsuji, I . Eur. Pat. Appi., EP 193 154, 3, Sep 1986,JP Appi. 65/36 839, 25 Feb. 1985, 29 pp. Chem. Abstr. 1987, 106,82958. (210) Martin, M. J.; Rolfe, P. Anal. Proc. 1986,23(8),303-304. (211) Oesch, U.; Ammann, D.; Pham, H. V.; Wuthier, U.; Zuend, R.; Simon, W. J . Chem. Soc. 1986, 82(4), 1179-1186. (212) Thode, J.; Boyd, J. C.; Ladenson, J. H. Clin, Chem. 1987, 33(10), 1811-1613. (213)Payne. R. B.; Jones, D. P. Ann. Clin. Biochem. 1987,24(4),400-407. (214) Bowers, G. N.; Brassard, C.; Sena, S. F. Clin. Chem. 1988, 32(8), 1437-1447. (215) Hua, H.; Wu, X.; Wang, P.; Cao, L. FenxiHuaxue 1987, 15(1),9-12. Chem. Abstr. 1987, 107, 130135. (216) Ortolano. G. A.; Terry, L. C. Microchem. J . 1987,35(3), 269-280. (217) Khaiil, S. A. H.; Moody, G. J.; Thomas, J. D. R. Anal. Lett. 1988, 19(17-18),1809-1830. (218)Metzger, E.; Dohner, R.; Simon, W.; Vonderschmitt, D. J.; Gautschi, K. Anal. Chem. 1987,59(13),1600-1603. (219) Treasure, J. L.; Pioth, D. W.; Treasure, T. Miner. Electrolyte Mefab. 1988, 72(3), 161-164. (220) Maruizumi, T.; Wegmann, D.; Suter, G.; Ammann, D.; Simon, W. Mlkrochim. Acta 1986, l(5-6),331-336.
Anal. Chem. 1988, 60, 113R-131R (221) Alybaeva, K. N. Zdarvookhr. Klrg. 1988, (6),22-24. Chem. Abstr. 1987, 106, 208924. (222) Scott, W. J.; Chapoteau, E.; Kamur, A. Clln. Chem. 1988, 32(11), 2119-2120. (223) Oesch, U.; Mallnowska, E.; Simon, W. Anal. Chem. 1987, 59(17), 213 1-2135. (224) Maas, A. H. J.; Weisberg, H. F.; Burnett, R. W.; Mueiler-Piathe, 0.; Wlmberley, P. D.; Zijlstra, W. 0.; Durst, R. A.; Siggaard-Andersen, 0. J. Clln. Chem. Clln. Blochem. 1987, 25(4),261-289. (225) Kobos, R. K.; Abbott, S. D.; Levin, H. W.; Kllkson, H.; Peterson, D. R.; Dlcklnson, J. W. Clin. Chem. 1987, 33(1),153-158. (226) Djamgoz, M. B. A.; Dawson, J. J. Biochem. Blophys. Methods 1986, 13(1),9-21. (227) Yamaguchi, H. Can. J . Physlol. Pharmacol. 1987, 65(5). 1006-1008. (228) Carllnl, W. G.;Ransom, B. R. Can. J. Physlol. Pharmacol. 1987, 65(5),889-893. (229) Ransom, B. R.; Carlini, W. G.; Yamate, C. L. Can. J. Physioi. Pharmacol. 1987, 65(5),894-897. (230) Kraig, R. P.;Cooper, A. J. L. Can. J. Physlol. Pharmacol. 1987, 8515). 1099-1 104. (23ij’-Ammann, D.; Chao, P.; Simon, W. Neurosci. Lett. 1987, 74(2), 221-226. (232) Stokols, M.; Corona, S. K.; Pucacco, L. R.; Jacobson, H. R.; Carter, N. W. A d . Blochem. 1987. 163(2),530-534. (233) Khalil, S. A. H.; Moody, G. J.; Thomas, J. D. R.; Lima, J. L. F. C. Analyst 1988, 111(6),611-617. (234) Oyama, N.; Hlrokawa, T.; Yamaguchi, S.; Ushlzawa, N.; Shlmomura, T. Anal. Chem. 1987, 59(2), 258-262. (235) Oesch, U.; Ammann, D.; Simon, W. Can. J. Physiol. Pharmacol. 1987, 65(5),885-688. (236) Schlue, W. R.; Deitmer. J. W. Can. J. Physlol. Pharmacol. 1987, 65(5)978-985. (237) Thomas, R. C. Can. J. Physiol. Pharmacol. 1887, 65(5), 1001-1005. (238) Feile, H.; Bertl, A. J . Exp. Bot. 1988. 37(182, 1416-1428. (239) LeFurgey, A.; Liu, S.; Lieberman, M.; Ingram. P. Microbeam. Anal. 1988, 2 1 S t , 205-208.
(240) Swandulla, D. Can. J. Physbl. Pharmacol. 1987, 65(5), 898-903. (241) Pucacco, L. R.; Corona, S. K.; Carter, N. W. Anal. Bbchem. 1988, 159(1), 43-49. (242) Lee, C. 0.; Im, W. B.; Sonn, J. K. Can. J . Physiol. Pharmacol. 1987, 65(5),954-962. (243) Oakiey, B. Can. J. Physlol. Pharmacoi. 1987, 65(5), 1018-1027. (244) Chao, A. C.; Armstrong, W. M. Am. J . Physlol. 1987, 253(2 Pt. l),
-- - - -
C3A3-C347 . .. .
(245) Lyall, V.; Croxton, T. L.; Armstrong, W. M. Biochlm. Blophys . Acta 1987, 903(1),56-67. (246) Yamaguchi, H. Cell Calcium 1986, 7(4), 203-219. (247) Ammann, D.; Buehrer, T.; Schefer, U.; Muelier, M.; Simon, W. Pfluegers Arch. 1987, 409(2), 223-228. Chem. Abstr. 1987, 107, 35847. (248) Morris, M. E.; MacDonald, J. F.; Friedllch, J. J.; Szekelyhldi I.Can. J. Physiol. Pharmacol. 1987, 65(5),926-933. (249) Toth, K.; Fucsko, J.; Lindner, E.; Feher, Z.; Pungor, E. Anal. Chlm. Acta 1988, 179,359-370. (250) Iicheva. L.; Trojanowlcz, M.; Krawczynski Krawczyk, T. Fres. 2. Anal. Chem. 1987, 328(1-2),27-32. (251) Christopouios, T. K.; Dlamandis, E. P. Analyst 1987, 112(9), 1293-1298. (252) Fan. W.; Fan, L. Fenxl Huaxue 1986, 14(5), 387-390. Chem. Abstr. 1988, 105, 128201. (253) Petak, P.; Stulik, K. Anal. Chlm. Acta 1988, 185,171-178. (254) Frenzel, W.; Braetter, P. Anal. Chlm. Acta 1988, 185, 127-136. (255) Frenzel, W.; Braetter, P. Anal. Chim. Acta 1988, 187, 1-16. (256) Cardwell, T. J.; Cattrall, R. W.; Hauser, P. C.; Hamilton, I.C. Anal. Chem. 1987, 59(1),206-208. (257) Van Staden. J. F. Anal. Chlm. Acta 1988, 179,407-414. (256) Van Staden, J. F. Fres. 2. Anal. Chem. 1987, 328(1-2),68-70. (259) Ilcheva, L.; Cammann, K. Res. 2. Anal. Chem. W88, 325(11), 11-14. (260) Lockridge, J. E.; F&r, N. E.; Schmuckler, G.; Fritz, J. S. Anal. Chlm. Acta 1987; 192(1),41-48. (261) Martin, G. B.; Meyerhoff, M. E. Anal. Chlm. Acta 1988, 186, 71-80. (262) Chang, Q.;Meyerhoff, M. E. Anal. Chim. Acta 1988, 186, 81-90. ’
Atomic Mass Spectrometry David W . Koppenaal Bureau of Economic Geology, The University of Texas at Austin, Austin, Texas 78713
INTRODUCTION AND SCOPE This inaugural fundamental review assimilates and summarizes recent developments in atomic mass spectrometry, as reported in the scientific literature published from November 1985 to late 1987. Atomic mass spectrometry is defined as the mass spectrometric measurement of atomic (as opposed to molecular or polyatomic) ions, for the primary purpose of elemental and/or isotopic composition determinations. The ”atomic mass Spectrometry” terminology is preferred for this review over the more commonly used ‘inorganic mass spectrometry”term since it better reflecta the elemental and isotopic emphasis of the review and also precludes the coverage of mass spectrometric investi ations involving organometallic compounds, chelates, metal cfuster ions, and 88eou8 metal chemistry, which are not reviewed here (but whict have been reviewed elsewhere (1-3)). Consistent with the aim of this journal, atomic mass spectrometry methods development, evaluation, and application studies placing emphasis on quantitative analysis were considered most pertinent in the preparation of this review. Atomic mass spectrometry is not a new field indeed it was the original application for mass spectrometry (MS) when developed for the isotopic compositional analysis of the elements. Com letion of the isotopic characterization of the elements a n x application of the MS technique to organic analysis in the early 1940s led to a diminished interest in atomic mass spectrometry, although thermal ionization and stable isotope ratio (TIMSand SIRMS, respectively) methods were clearly being refined at that time. Subsequent interest in solids analysis by mass spectrometryled to the development of the well-known spark-source mass spectrometry (SSMS) technique in the late 1950s. This technique dominated atomic spectrometry interest until the late 1960s,when rapid investigation and development of modern techniques began. Research and development activity during the last 15 years 0003-2700/88/0360-113R$06.50/0
has resulted in the availability of secondary ion, laser microprobe, glow-discharge, inductively coupled plasma, resonance ionization, and accelerator mass spectrometry techniques (acronyms SIMS,LMMS, GDMS, ICPMS, RIMS,and AMs,respectively). The present review covers these and other developing atomic mass spectrometric methodologies. This review is based on a computerized Chemical Abstracts search of titles, keywords, and abstracts of literature published in the last 2 years. Selected literature from earlier publications is cited where appropriate (i.e., general technique reviews). Government reports and conference proceedings are cited only when other corresponding literature references were not available. Foreign journals are likewise represented only in the absence of other available literature; however, for several subject areas foreign contributions were dominant and had to be included. Accession numbers from Chemical Abstracts are provided with foreign literature citations. Over 2500 literature citations were examined; this review is a result of a somewhat selective and critical evaluation of these search citations. Oversight or omission of certain contributions is inevitable; an advance apology is offered for such cases. Applications of analytical techniques are the ultimate justification for new technique development and are consequently included in this review, typically in an abbreviated tabular format due to space constraints. Reference to these applications is encouraged for pragmatic technique use and efficacy evaluation. Detailed review of such applications is deferred to the alternate-year application reviews of this journal. A. BOOKS,REVIEWS, AND PERIODICALS New books, general reviews, and periodical literature covering atomic mass spectrometry developments are addressed in this section. Mass spectrometry is a dynamic technique and therefore many books have been published recounting recent developments. Many of the mass spectrometry texts 0 1988 American Chemical Society
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