| Crynodeb: | The oxidation of cysteine by ferricyanide is well established. However, electrochemical studies of the mechanism have to date been underdeveloped due to the lack of resolution between the oxidation waves of the ferrocyanide and cysteine on most electrode materials. It is shown that on boron doped diamond electrode, unlike for example platinum electrodes, the voltammetric responses of the ferrocyanide wave and the targets are sufficiently different, with the former at a lower oxidizing potential, to permit examination of the kinetics of the homogeneous oxidation via voltammetric methods. Accordingly conventional cyclic voltammetry using a BDD electrode is used to show that an EC′ mechanism occurs and rate constants deduced. Both the protonated and de-protonated forms of cysteine (pKa = 10.5) are shown to undergo oxidation by ferricyanide. The cyclic voltammetry data obtained is corroborated by use of channel flow cell experiments with excellent agreement shown between the two techniques for deduced values of the homogeneous electrocatalytic rate constants: Channel electrodes are seen to provide a convenient means to allow quantitative mechanistic hydrodynamic voltammetry at BDD electrods.
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