Polarographic maxima revisited

The relation between maxima (of the first kind) and drop lifetime-potential (TE) curves was investigated by recording both the DC polarogram and the TE curve and comparing the latter to that obtained with the blank solution, under identical conditions. The advanced instrumentation for measuring drop life-time allowed the detection of minute variations occurring in various regions of the applied potential range. Positive maxima were studied with CUII/ClO, CuII/Cl−, PbII/Cl−, FeIII/C2O and UO/C2O systems; negative maxima, with solutions of NiII, ZnII and PbII. Hypotheses explaining the variations in maximum shape and height and in drop lifetime, taking into account the nature of the electroactive species (mainly, the location of the reduction step vs. the pzc), or the supporting electrolyte concentration are submitted, including the differing behavior observed with positive and negative maxima.