Voltammetry with Diminished Supporting Electrolyte

Using the voltammetric technique of semiintegral electroanalysis, a study has been made of the effect of decreasing the supporting electrolyte concentration to a level at which it can no longer be considered to be in excess. An imperfect theory predicts that, for the reduction of metal cations, the voltammetric signal under conditions of complete concentration polarization will exceed that in the presence of excess supporting electrolyte by the factor, where is the fraction of the ionic strength contributed by the electroactive ion, while and are the diffusion coefficients of the electroactive and supporting ions. Experiments on three systems have confirmed these predictions for ratios in the range 0–0.3.