Chemically modified electrodes based on noble metals, polymer films, or their composites in organic voltammetry

The review deals with the current state of and prospects for the use of electrodes modified with noble metals, polymer films, or composites on their basis, which yield catalytic response in voltammetry. Techniques of applying noble metals, polymer films, or their composites to a conducting support are considered. The catalytic properties of immobilized redox mediators and the analytical, operating, and performance characteristics of this type of modified electrodes are compared. © 2008 MAIK Nauka

Determination of Ascorbic Acid by Electrocatalytic Response of an Electrode Coated with Polyvinylpyridine Film and Palladium-Plated

A procedure was developed for analysis of ascorbic acid with a carbon glass electrode coated with a palladium-modified poly(2-vinylpyridine) film

Flow-injection determination of water-soluble vitamins B1, B2, and B6 from the electrocatalytic response of a graphite electrode modified with a ruthenium(III) hexacyanoruthenate(II) film

The electrochemical behavior of water-soluble vitamins B1, B2, and B6 at an unmodified graphite electrode and a graphite electrode modified with an inorganic film of ruthenium(III) hexacyanoruthenate(II) was studied. The electrocatalytic activity of the metal complex in the oxidation of vitamins was found. Ru(IV) species act as a catalyst. Conditions for recording voltammograms and hydrodynamic conditions for detecting the maximum catalytic current in flow-injection analysis (FIA) were selected. Procedures for the amperometric detection of thiamine, riboflavin, and pyridoxine were proposed. © Pleiades Publishing, Inc., 2006

Copper oxide based electrodes in voltammetric analysis for sulfides

Modified copper(II) oxide based electrodes are proposed for electrochemical analysis for sulfides. The mechanism was studied of electrooxidation of sulfides on metal oxide electrodes. A method was developed of quick voltammetric analysis for sulfides. Conditions were revealed under which the maximum intensity of analytical signal is registered. The method can be used for ecoanalytical monitoring of industrial, waste, and natural water. ©1998 MAHK Hayka/Interperiodica Publishing

Electrocatalytic determination of organic thiocarbonyl compounds using a carbon-paste electrode modified with cobalt phthalocyanine

Results of a voltammetric study of organic thiocarbonyl compounds (thiourea, thioacetamide, thiobenzamide, and dithiooxamide) using a carbon-paste electrode modified with cobalt phthalocyanine are reported. The electrode thus designed shows good reproducibility of voltammetric measurements and can be used for analytical determination of organic compounds containing a thionic group. © 1999 Kluwer Academic/Plenum Publishers

Amperometric cholinesterase biosensors with carbon paste electrodes modified with cobalt phthalocyanine

Biosensors based on a carbon paste electrode with immobilized cholinesterase and cobalt(II) phthalocyanine as a mediator are studied. Electrochemical characteristics of the biosensors are investigated in relation to the carbon paste composition, the enzyme and mediator immobilization procedures, nature of the protective film and procedure of its application, and also storage conditions of the electrodes. A method is suggested for fabricating a cholinesterase biosensor with cobalt(II) phthalocyanine mediator, providing the maximum electrocatalytic response in electrooxidation of butyrylthiocholine iodide (substrate for cholinesterase)

Stripping-voltammetric determination of some amino acids on a carbon-paste electrode modified by crown ethers

A method for detecting sulfur-containing amino acids on a carbon-paste electrode modified by dibenzo-18-crown-6 or dibromodibenzo-18-crown-6 ethers is developed. The selectivity of the method is accounted for by a specific interaction between crown ethers (modifying agents) and protonated amino groups of organic molecules of the analyte adsorbed by the surface of the modified electrode as a host-guest complex. The determination limits (clim) of cysteine, homocysteine, and glutathione are equal to (2-5) x 10-8 M. © 1997 MAEe Cyrillic signK Hayκa/Interperiodica Publishing

Electrocatalytic determination of dithiocarbamate-based pesticides using electrodes modified with metal phthalocyanines

An electrocatalytic method has been proposed for determining dithiocarbamate-based pesticides (carbathion, nabam, ferbam, thiram, and thiuram) using a carbon-paste electrode modified with iron(II) and cobalt(II) phthalocyanines. The first wave of carbathion oxidation in botli aqueous and organic solutions does not change compared to an unmodified carbon-paste electrode; for the second stage of oxidation, a decrease by 100 mV in the overpotential and a significant increase in the current are observed. The electrochemical signal is observed in the range of potentials characteristic for the oxidation of metal phtlialocyanines, and the metal phthalocyanine serves as the electron carrier. A similar effect is observed for the electrochemical oxidation of nabam. The catalytic activity of the metal phtlialocyanines to ferbam, thiram, and thiuram in acetone has been determined. In the case of the electrochemical oxidation of ziram and zineb, the electrocatalytic effect is not observed. The dependence of the peak current on the pesticide concentration is linear within the range from 1 × 10-3 to 1 × 10-7 M. The adsorption preconcentration of pesticides decreases the limit of detection by an order of magnitude. © 2001 MAIK "Nauka/Interperiodica"

Electrocatalytic oxidation and flow-injection determination of ascorbic acid at a graphite electrode modified with a polyaniline film containing electrodeposited palladium

A method for forming a composite film on the surface of a graphite electrode is proposed. Conditions for detecting the maximum catalytic current under batch and flow conditions are determined. A procedure for the electrocatalytic determination of ascorbic acid at the graphite electrode modified with a polyaniline film containing palladium particles is proposed. The catalytic effect of this electrode manifests itself by a ∼300-mV decrease in the peak potential of ascorbic acid oxidation and by a multiple increase in the peak current of ascorbic acid oxidation as compared to the unmodified electrode. The linear dependence of the electrocatalytic response of the composite electrode on the concentration of ascorbic acid is observed down to 1 × 10-8 M and 2.5 nmol of ascorbic acid under batch and flow-injection analysis conditions, respectively. © Pleiades Publishing, Inc., 2006

Copper oxide based electrodes in voltammetric analysis for sulfides

Modified copper(II) oxide based electrodes are proposed for electrochemical analysis for sulfides. The mechanism was studied of electrooxidation of sulfides on metal oxide electrodes. A method was developed of quick voltammetric analysis for sulfides. Conditions were revealed under which the maximum intensity of analytical signal is registered. The method can be used for ecoanalytical monitoring of industrial, waste, and natural water. ©1998 MAHK Hayka/Interperiodica Publishing