A study of the electrochemical characteristics of some thiols by differential pulse polarography and other electrochemical techniques

A study of some low-molecular-weight odorous thiols at mercury electrodes has been made by differential pulse polarography (d.p.p.), d.c. polarography, linear-sweep voltammetry, and coulometric measurement on linear-sweep reduction. Linear current versus concentration plots are found for individual thiols, in aqueous 0.2 M sodium hydroxide by using d.p.p. at thiol concentrations from ca. 2 × 10^-7 M to 10^-4 M. A linear trend between peak potential and molecular weight was found for homologous series, but the method cannot be used for qualitative identification because of peak shifts in multicomponent mixtures. The electrode reactions show quasireversible behavior. At concentrations of thiol greater than 10^-4 M, the single peak splits into two peaks and film formation occurs. Charge density versus concentration plots indicate that the quantity of adsorbed material is several monolayers.