CV studies performed in our laboratory previously showed that Ga(III)/Ga electrode process in mixed electrolyte medium
(4M NaClO4 + 0.5M NaSCN) at SMDE is diffusion controlled and close to reversibility. Electro-reduction of Ga(III) occurs at −0.820V and is a slow electrode process as compared to electro-oxidation of Ga which occurs at −0.800V [17]. In view
of this, CPC studies were first carried out for the optimization of potentials for quantitative reduction of Ga(III) to Ga and then oxidation of Ga to Ga(III), in the mixed electrolyte medium at stirring mercury electrode. In the reduction step, potentials more negative compared to −0.820V, in the range of −0.90 to −1.05V, were applied and a reduction potential of −0.95V was found to be the most optimum. Potentials more positive than −0.800Vwere applied to study quantitative electro-oxidation of Ga to Ga(III) and an oxidation potential of −0.6V was found to be optimum. Achieving minimum and stable background current for 1–2 min, in the reduction as well as in the oxidation step, was the guide line adopted for detecting the end-point of exhaustive electrolysis. In the present studies, as will be seen below, the level of background current observed in the reduction step was much higher compared to the reported values of coulometric blanks.