Response of Microvoltammetric Electrodes to Homogeneous Catalytic and Slow Heterogeneous Charge-Transfer Reactions

Mark A. Dayton, Andrew G. Ewing, R. Mark Wightman

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Abstract

Voltammetric electrodes whose area is defined by the radius of a carbon fiber (2.8 μm) have been used in the electrooxidation of dopamine, dihydroxyphenylacetfc acid, and ascorbic acid. The results are compared to those predicted by the equations for a hemispherical electrode of identical radius. The equations are derived by evaluating the pertinent flux equations that were derived in spherical coordinates. Charge-transfer rates deduced from this analysis are found to be the same at carbon fiber electrodes as at carbon paste for dopamine oxidation. The quasi-reversible behavior of dihydroxyphenylacetic acid at carbon paste is accentuated at the fiber employed in this report. Because of the small size of carbon fibers, enhanced current from the catalytic oxidation of ascorbic acid by oxidized dopamine is minimized. The result is also in accord with that predicted by the equations for a homogeneous catalytic reaction at a hemispherical electrode of similar dimensions.

Original languageEnglish (US)
Pages (from-to)2392-2396
Number of pages5
JournalAnalytical Chemistry
Volume52
Issue number14
DOIs
StatePublished - Dec 1 1980

All Science Journal Classification (ASJC) codes

  • Analytical Chemistry

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