Electrochemically initiated reactions of diphenylamines with sulfide: Application to the voltammetric detection of hydrogen sulfide

The electrochemical behavior of three diphenylamine derivatives in the presence of sulfide and sulfhydryl thiols (RSH) in aqueous solution on a glassy carbon electrode has been investigated. All three are shown to exhibit modified voltammetric profiles upon the addition of low concentrations of sulfide, which may provide alternative routes for the detection of this important analyte. The various strategies within which they can be employed have been identified and a brief comparison of their analytical utility (limit of detection, linear range, selectivity etc.) compiled. The reaction of sulfide with 4,4-diaminodiphenylamine is shown to be particularly promising with a number of options through which sulfide levels could be identified. Evidence for the electrochemical formation of the sulfur heterocycle, thionine, is presented and the potential advantages of such reactions highlighted.