Differential Pulse Polarography applied to Aromatic Disculfides

The differential-pulse polarographic behaviour of p-tolyl disulphide, 3-nitrophenyl disulphide and benzyl disulphide was investigated as a function of pH and concentration. At pH 11.4, with a 50% methanol solution as the solvent, a linear relationship between peak current and concentration was obtained for each compound over at least two orders of magnitude at a static mercury drop electrode; the detection limits were 0.2 µM in each instance. The pre-wave observed in the reduction of p-tolyl disulphide and 3-nitrophenyl disulphide was shown to be caused by chemical reactions with mercury rather than by simple adsorption.