Electrochemistry of Thiols

The EC activity of thiols was discovered by Dixon and Quastel, who reported the anodic oxidation of cysteine. Of more analytical relevance was the characterisation 

Lee and Mairesse-Ducarmois et using fast linear sweep and differential 

Strides and Kolthofif using DC polarography found that between pH 1 and pH 10.5 and at ca -0.25 V vj SCE, Reaction 5.2 also applied to GSH. Mairesse-Ducarmois et showed that following the oxidation of GSH, the product, GSHg, was adsorbed onto the mercury surface. Similar results have been observed with silver electrodes. Gold amalgam electrodes can also be used (see below). 

Thiols can be oxidised at a variety of solid electrodes, such as noble metals, carbon and carbon with chemically modified surfaces. Mefford and Adams found that relatively high voltages, greater than -1-1 V, were required to oxidise GSH and cysteine at glassy carbon electrodes. Chemically modified surfaces can reduce the oxidation potentials required and hopefully increase specificity and sensitivity. Halbert and Baldwin used cyclic voltammetry to study the electrochemistry of cysteine, homocysteine, A -acetylcysteine and GSH at both unmodified and cobalt phthalocyanine-modified carbon paste electrodes. This non-chromatographic technique was used to measure the relatively high concentrations of GSH in whole blood. The electrochemistry of thiols has been reviewed.  

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Li J, Zou G, Hu X, Zhang X (2009) Electrochemistry of thiol-capped CdTe quantum dots and its serrsing applicatiorL J Electroanal Chem 625 88-91... 

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