POLAROGRAPHIC MAXIMA REVISITED

The relation between maxima (of the first kind) and drop lifetime-pote ntial (TE) curves was investigated by recording both the DC polarogram and the TE curve and comparing the latter to that obtained with the b lank solution, under identical conditions. The advanced instrumentatio n for measuring drop life-time allowed the detection of minute variati ons occurring in various regions of the applied potential rang. Positi ve maxima were studied with Cu-II/ClO4-, Cu-II/Cl-, Pb-II/Cl-, Fe-III/ C2O42- and UO22+/C2O42- systems; negative maxima, with solutions of Ni -II, Zn-II and Pb-II. Hypotheses explaining the variations in maximum shape and height and in drop life-rime, taking into account the nature of the electroactive species (mainly, the location of the reduction s tep vs. the pzc), or the supporting electrolyte concentration are subm itted, including the differing behavior observed with positive and neg ative maxima.