UPCOMING RESEARCH
Use of Electrochemical Microscopy To Examine Counterfon Ejection from Nation Coatings on Electrodes
Chromium Detection by Laser Desorption and Resonance Ionization Mass Spectrometry
Os(bpy)| + cations incorporated into Nafion coatings on electrodes to the maximum extent are oxidized at unusu ally positive potentials to Os(bpy)| + cations, which are partially ejected from t h e coatings to maintain electroneutrality. This ejection is monitored by electrochemical microscopy. Chongmok Lee and Fred C. Anson*, Arthur Amos Noyes Laboratories, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125
Ionization is effected by a 2+1 (photons to resonance + photons to ionize) process, and the detection limit for this analysis is ~ 10 fg. N. S. Nogar*, Chemical and Laser Sciences Division, MS J565, Los Alamos National Laboratory, Los Alamos, NM, 87545 and R. C. Estler, Department of Chemistry, Fort Lewis College, Durango, CO 81301
Hematin as a Peroxidase Substitute in Hydrogen Peroxide Determinations Hematin constitutes a n inexpensive stable substitute for horseradish peroxidase in H 2 0 2 determinations. Low na nomolar detection limits are possible with phenolic sub strates by fluorometry. Zhang Genfa and Purnendu K. Dasgupta*, Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409-1061 Water-in-Oil Microemulsions as Solvents for Laser-Excited Multiphoton Photoionization Laser-excited multiphoton photoionization of species in water-in-oil microemulsions allows study of species in polar and conductive solvent systems. Noise levels are reduced relative to water, b u t signal levels are also de pressed Linearity and precision are improved, especially with acid salts. Mitchell E. Johnson and Edward Voigtman*, Department of Chemistry, University of Massachusetts at Amherst, Amherst, MA 01003-0035 Laser-Induced Surface-Plasmon Desorption of Dye Molecules from Aluminum Films Rhodamine Β molecules are desorbed without fragmenta tion from t h e surface of an aluminum film by surfaceplasmon-induced desorption. The desorption yields of both Al and rhodamine Β show a dependence on inci dence angle that peaks a t the plasmon resonance angle. Ida I on* T A r.allcntf and Ε Τ Arakawa Health and Safety R e U L h Division Oak Ridge N a t X l l b o r a ^ Oak RWge,TO37831 6 m
These articles are scheduled to appear in AC RESEARCH in the n e a r future.
Potentiometric and Voltammetric Investigations of H 2 /H + Catalysis by Periplasmic Hydrogenase from Desulfovibrio gigas Immobilized at the Electrode Surface in an Amphiphilic Bilayer Assembly Immobilization of hydrogenase-type enzyme a t the elec trode surface in an amphiphilic bilayer assembly consist ing of octadecyltrichlorosilane and octadecylviologen mol ecules involves hydrophobic interactions and leads to enzymatic electrocatalysis. Thierry Parpaleix, Jean Marc Laval, Marcin Majda\ and Christian Bourdillon*, Laboratoire de Technologie Enzymatique, URA 1442 du CNRS, Université de Compi6gne, BP 649, 60206 Compiégne Cedex, France Selective lonophore-Based Optical Sensors for Ammonia Measurement in Air Dynamic response characteristics and selectivities for ammonia with respect to other normally occuring gases under varying relative humidity a r e studied for several membrane formulations. There is no deterioration in response after four months in laboratory air. Steven J. West Satoshi Ozawa Kurt Seiler Susie S. S. Tan and Wilhehn Simon*, Department of Organic Chemistry, Swiss Federal Institute of Technology (ETH), Universitâtstrasse 16, CH-8092 Zurich, Switzerland Determination of Formation Constants for β-Cyclodextrin Complexes of Anthracene and Pyrene Using Reversed-Phase Liquid Chromatography The effects of β-cyclodextrin and terf-butyl alcohol or cyclopentanol as mobile-phase modifiers for the separation of two polyaromatic hydrocarbons are examined. The for m a t i o n c o n s t a n t s for t h e P - C D : a n t h r a c e n e a n d P-CDovrene inclusion complexes are determined, and the solubihty and selectivity enhancement implications of these effects are discussed. Vincent C. Anigbogu, Arsenio Mufioz de la Pefia, Thilivhali T. Ndou, and Isiah M. Warner*, Department of Chemistry, Emory University, Atlanta, GA 30322
*Corresponding author ANALYTICAL CHEMISTRY, VOL. 64, NO. 4, FEBRUARY 15, 1992 · 253 A
UPCOMING RESEARCH Quantitative Analysis of Short-Chain Phosphates by Phosphorus-31 Nuclear Magnetic Resonance and Interlaboratory Comparison with Infrared and Chromatographic Methods
Improvement of Multivariate Calibration through Instrument Standardization
Precision and accuracy of NMR spectroscopy for the analysis of oligophosphates are determined with an optimized method. Direct method comparisons are conducted for NMR and IR spectroscopy and chromatography in interlaboratory analyses. David R. Gard*, John C. Burquin, and Janice K. Gard*, Monsanto Company, 800 North Lindbergh Boulevard, St. Louis, MO 63167
The standard error for prediction from standardization can be better than that of full-set recalibration when the response on one instrument is standardized into that of a higher quality instrument and the calibration model built on the latter is used for prediction. Yongdong Wang, Michael J. Lysaght, and Bruce Kowalski , Center for Process Analytical Chemistry and Department of Chemistry BG-10, University of Washington, Seattle, WA 98195 Temperature Programming in Capillary Zone Electrophoresis
A Hole Can Serve as a Microelectrode A constriction between an electrode and the solution acquires some of the properties of a microelectrode. The effect of such constrictions can be misinterpreted as erroneously large electron-transfer rate constants. Keith B. Oldham, Trent University, Peterborough, Canada K9J 7B8
Dynamic changes of pH in capillary zone electrophoresis can be generated by using a buffer system with a large temperature coefficient in conjunction with temperature control of the capillary. Chen-Wen Whang and Edward S. Yeung*, Ames Laboratory-USDOE and Department of Chemistry, Iowa State University, Ames, IA 50011
Optoelectrochemical Thin-Film Chlorine Sensor Employing Evanescent Fields on Planar Optical Waveguides
Effect of Temperature on Separation Efficiency for High-Speed Size Exclusion Chromatography
The sensor is based on an electrochemical thin-film sensing layer placed on top of a planar waveguide. The oxidation state of the sensing film is quantitatively measured by the evanescent field of the light transmitted through the waveguide. Christophe Piraud, Eustace Mwarania, George Wylangowski, and James Wilkinson, Optoelectronics Research Centre, Southampton University, Southampton S09 5NH, England and Kieran O'Dwyer and David J. Schiffrin*, Chemistry Department, University of Liverpool, P.O. Box 147, Liverpool L69 3BX, England Sensitive Layer for Electrochemical Detection of Hydrogen Cyanide Development and evaluation of a sensitive layer for detection of HCN based on a polyaniline/metal system is described. Jan Langmaier and Jiri Janata*, Department of Materials Science and Engineering, University of Utah, Salt Lake City, UT 84112 Identification of Chemical Constituents by Multivariate Near-Infrared Spectral Imaging
Theoretical relationships t h a t predict separation efficiency a n d a n a l y s i s t i m e should improve for hight e m p e r a t u r e SEC of macromolecules. T e m p e r a t u r e s ranging from 25 °C to 150 °C are experimentally investigated, yielding a fourfold improvement in analysis time and separation efficiency. Curtiss N. Renn and Robert E. Synovec*, University of Washington, Center for Process Analytical Chemistry, Seattle, WA 98195 Sensitivity Comparison in a Microwave-Induced Plasma Gas Chromatographic Detector: Effect of Plasma Torch Design One of t h e key components in a microwave-induced plasma detection system is the plasma torch. The analytical performance of two different plasma torch designs is evaluated in terms of sensitivity and detection limits. Measurements are made using ionic emission, molecular emission, and reflected power. Rosa M. Alvarez Bolainez, Michael P. Dziewatkoski, and Charles B. Boss*, Department of Chemistry, North Carolina State University, Box 8204, Raleigh, NC 27695-8204
The efficiency of a near-IR spectroscopic imaging system is tested. Discriminant analyses are applied to images recorded between 900 and 1900 nm to identify bran, gluten, and starch in wheat. Paul Robert*, Dominique Bertrand, Marie Françoise Devaux, and Alain Sire, Institut National de la Recherche Agronomique, Centre de Nantes, B.P. 527 rue de la Géraudière, 44026 Nantes Cedex 03, France
ANALYTICAL CHEMISTRY, VOL. 64, NO. 4, FEBRUARY 15, 1992 · 255 A
UPCOMING RESEARCH Optimal Minimal Neural Interpretation of Spectra OMNIS is based on principal component analysis and artificial neural networks. It is useful for the classification or quantitation of visible and near-IR spectra as well as sound or any other large quantity of correlated data. OMNIS reduced the standard error of prediction on two near-IR data sets by 5 0 - 7 5 % as compared with PCR and PLS. Claus Borggaard* and Hans Henrik Thodberg, The Danish Meat Research Institute, Maglegaardsvej 2, DK-4000 Roskilde, Denmark Spray Extraction of Volatile Organic Compounds from Aqueous Systems into the Gas Phase for Gas Chromatography/Mass Spectrometry Volatile and semivolatile organic compounds in aqueous systems can be extracted into the gas phase by dispersing very small droplets of the liquid phase in a carrier gas. Low concentrations (down to 1 0 - 3 0 ng/L with 2 min of sampling) of contaminants can be determined by GC/MS using spray-and-trap sampling. Gôkhan Baykut* and Annette Voigt, Bruker-Franzen Analytik GmbH, Fahrenheit Str. 4, 2800 Bremen 33, Germany
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ANALYTICAL CHEMISTRY, VOL. 64, NO. 4, FEBRUARY 15, 1992 · 257 A
