Characterisation of Prussian blue modified screen-printed electrodes for thiol detection

The electrocatalytic behaviour of Prussian blue towards thiol oxidation was thoroughly investigated. Cyclic voltammetry experiments performed in thiol solution showed the classical shape of a mediated redox system. The current due to thiol-mediated oxidation was then evaluated in batch amperometric mode at +200 mV vs. Ag\AgCl. Many thiocompounds were investigated and their different reactivities were discussed. Thiocholine and cysteamine were found to give the best results in terms of LOD (i.e., 5 x 10(-6),10(-6) mol l(-1), respectively) and linear range (5 x 10(-6)-5 x 10(-4),10(-6)-10(-4) mol l(-1), respectively). Two applications are also proposed, one involving the measurement of thiocholine as a mean for pesticide detection, and the other being an electrochemical alternative to Ellman's test for total thiol estimation. (C) 2003 Elsevier B.V. All rights reserved.