Detection at Other Solid Electrodes

Carbon electrodes were used for thiol analysis by Mefford and Adams at potentials +1 V Ag/AgCl. As little as 5 pmol of cysteine and GSH could be measured 

Carro-Ciampi et al. used dual PGEs to detect GSH and GSSG. The upstream electrode was at +0.7 V, presumably to reduce background interferences, and analytes were detected at the downstream electrode held at +0.9 V vs Pd. Maximum sensitivity was 1.5 ng GSH injected, but even using a clean-up electrode sensitivity was lost over 100 analyses. Stulik and Pacakova measured standard solutions of thiouracil at +1.4 V at a carbon paste electrode. 

These observations at un-modified metal surfaces led to electrodes of this type being used in amperometric detectors. Kreuzig and Frank oxidised 

D-penicillamine at a gold electrode at +0.8 V vi Ag/AgCl following cation-exchange chromatography, and found comparable sensitivity to the Au/Hg 

In the FIA studies mentioned earlier platinum electrodes gave a secondary peak only with cysteamine. In a subsequent assay cysteamine was separated by iso-cratic SCX-HPLC and detected at +0.45 V vs Ag/AgCl. The analysis time was less than 3 min. 

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