摘要:

AbstractAn overview on pharmaceuticals treated by electroanalytical techniques is presented. The review covers the period between 1987 and 1990 and includes more than 100 references. It includes the use of mercury and solid modified electrodes. Recent trends are discussed. The coverage is not exhaustive.

ISSN:1040-0397    

DOI:10.1002/elan.1140020802

出版商:VCH Verlagsgesellschaft mbH    

年代:1990

数据来源: WILEY

摘要:

AbstractA new automated polarographic cell is described. The sample solution is pressurized and forced into the cell through a short glass tube. A thin film of the solution is formed on the inside wall of the tube while the nitrogen flows in the center. Equilibrium (and deoxygenation) is achieved very rapidly. Comparison of the thin film cell and the previous nebulizer automated cell clearly shows the advantages of the new device in terms of sample collection efficiency, sample volume, and nitrogen consumption.

ISSN:1040-0397    

DOI:10.1002/elan.1140020803

出版商:VCH Verlagsgesellschaft mbH    

年代:1990

数据来源: WILEY

摘要:

AbstractThe effect of increasing the cross‐linking of poly(4‐vinylpyridine) films on glassy carbon substrates for the electrochemical deposition of Ag microparticles has been investigated. Cyclic voltammetric patterns for the deposition and stripping processes are elucidated. The electrochemical potential required for the deposition shifts to more negative values with cross‐linking. These shifts can be attributed to the polymer becoming more compact and to increased electrical resistance. There are two different components to this resistance. One is related linearly to the thickness of the film, while the other is independent of thickness. Both components are, however, related to the degree of cross‐linking. For the first component, the effect may be due to an increase in the resistance for electrolyte transport through the polymer channels constricted by the cross‐linking. The other is attributed to the increased resistance for water and electrolyte penetration from the solution phase into the polymer, whose hydrophobicity is increased by the cross‐linking and, thereby, is unwetted and insulative. Useful information regarding the permeability of the cross‐linked polymer is obtained by using silv

ISSN:1040-0397    

DOI:10.1002/elan.1140020804

出版商:VCH Verlagsgesellschaft mbH    

年代:1990

数据来源: WILEY

摘要:

AbstractThe ergot alkaloids, ergotamine tartarate, ergonovine maleate, and ergocristine, are shown to be effectively partitioned into a lipid layer on a glassy carbon electrode. Such hydrophobic accumulation greatly enhances the sensitivity and selectivity of the subsequent voltammetric scan. A high degree of selectivity is achieved as polar electroactive species (present at large excess) are excluded by the hydrophobic layer. Detection limits of 1 × 10−8M for ergotamie tartarate, 3 × 10−7M for ergocristine, and 1 × 10−6M for ergonovine maleate are attained (3 minute accumulation). Numerous variables affecting the response are explored. Differences in the hydrophobicity of ergot alkaloids account for changes in hydrophobic uptake and, hence, sensitivity. Applicability to selective measurements in untreated urine samples is ill

ISSN:1040-0397    

DOI:10.1002/elan.1140020805

出版商:VCH Verlagsgesellschaft mbH    

年代:1990

数据来源: WILEY

摘要:

AbstractNew polymeric membrane electrodes based on the ion‐associated species formed by the cyanide of gold with hydrophobic cations, reversible to gold cyanide complex ions, were examined. Most exhibit a linear response with a nearly Nernstian slope over the 10−5to 10−2M concentration range of dicyanoaurite. The electrodes have been applied to the determination of gold in various cyanide electroplating

ISSN:1040-0397    

DOI:10.1002/elan.1140020806

出版商:VCH Verlagsgesellschaft mbH    

年代:1990

数据来源: WILEY

摘要:

AbstractA flow‐injection system with anodic amperometric detection for glucose determination in human blood serum samples was optimized by a comparison of various arrangements of enzyme immobilization and the elimination of interferences. The best results were obtained using a compact membrane biosensor in a wall‐jet, flow‐through detector with a platinum disk electrode covered with an evaporated Nafion layer, a polyester membrane with immobilized glucose oxidase, and another protective polyester membrane. In the optimized conditions, a linear response was observed up to 25 mM glucose with a detection limit of 200 μM glucose and a sampling rate of 120 samples/h for a 20 μL sample volume. Results of glucose determination in human serurn were compared with a Beckman Glucose Analyzer 2 and a Kone Dynamic a

ISSN:1040-0397    

DOI:10.1002/elan.1140020807

出版商:VCH Verlagsgesellschaft mbH    

年代:1990

数据来源: WILEY

摘要:

AbstractHydroxide is oxidized to oxygen at 0.7 V versus a saturated calomel electrode in a pH 11 solution at a glassy carbon electrode modified with a film containing palladium and iridium oxide. Although this converts to a value that is among the lowest of the reported overpotentials for this reaction, the utility for large‐scale electrolyses is limited by the need to periodically reactivate the surface with an acid treatment. The reaction, however, has considerable promise for electroanalytical chemistry. Voltammetric working curves in the millimolar range are linear at slow scan rates; at 40 mV/s, the sensitivity is 241 mA/mol. The current is mass transport limited at a rotating disk electrode. A general mechanism, proposed in part on the basis of a Tafel plot, is presente

ISSN:1040-0397    

DOI:10.1002/elan.1140020808

出版商:VCH Verlagsgesellschaft mbH    

年代:1990

数据来源: WILEY

摘要:

AbstractThis article describes anion transfer across a conducting polypyrrole membrane (PPM) using cyclic voltammetry with a four‐electrode system. The transfer process of both chloride and nitrate anions across the polypyrrole membrane used to separate two pools of electrolyte solutions has been studied. A wide potential window beyond 3 V was obtained, and well‐developed voltammograms for the transfer of nitrate and chloride anions appeared within this window. The transfer process depends on the ion size, the ion charge, and the surface characteristics of the polypyrrole membrane. The one‐way transfer phenomenon observed in different potential‐bias directions can be explained by the asymmetrical ion channel model of the polypyrrole m

ISSN:1040-0397    

DOI:10.1002/elan.1140020809

出版商:VCH Verlagsgesellschaft mbH    

年代:1990

数据来源: WILEY

摘要:

AbstractA method is described for determining the dissociation potentials of metal complexes using computerized flow‐injection potentiometric stripping analysis (CFIPSA). The dissociation potentials of Bi:NTA and Bi:EDTA complexes are determined at pH 2 by measuring the bismuth(III) concentrations (i.e., the counts in solutions containing the 1:1 complexes at different deposition potentials between −0.15 and −0.90 V vs. Ag/AgCl). Dissociation potentials of −0.35 and −0.50 V vs. Ag/AgCl have been found for Bi:NTA and Bi:EDTA, res

ISSN:1040-0397    

DOI:10.1002/elan.1140020810

出版商:VCH Verlagsgesellschaft mbH    

年代:1990

数据来源: WILEY

摘要:

AbstractA simple and rapid method for the determination of the antibiotic ciprofloxacin by differential pulse polarography (DPP) has been developed. The changes in the voltammetric behavior of this drug compound with pH was studied, and the most suitable pH for analytical purposes was found to be pH 8.5. The DPP behavior of this compound at this pH exhibited two reduction waves at −1.44 and −1.64 V. The former wave could be used to determine ciprofloxacin between 5 × 10−7and 3 × 10−5M. The method was applied to the determination of ciprofloxacin in formulated tablets with a relative standard deviation of less

ISSN:1040-0397    

DOI:10.1002/elan.1140020811

出版商:VCH Verlagsgesellschaft mbH    

年代:1990

数据来源: WILEY