VOLTAMMETRIC REDUCTION OF NICKEL AND COBALT DIMETHYLGLYOXIMATE

The determination of cobalt and nickel in aqueous solutions by strippi ng voltammetry after adsorptive preconcentration is an established pro cedure. The method is highly sensitive, but there is some controversy concerning the reasons for the excellent sensitivity. Using a variety of voltammetric techniques, we have determined that the reduction of n ickel dimethylglyoximate in an ammonia buffer is consistent with an ov erall process involving 16 or possibly 18 electrons. This hypothesis i s confirmed by independently measuring the total quantity of metal ads orptively deposited on the mercury electrode and comparing the amount with the quantity of electricity required for its reduction.