Simultaneous determination of nickel(II) and cobalt(II) by square-wave adsorptive stripping voltammetry on a rotating disc mercury film electrode

Abstract

Adsorptive stripping voltammetry was used for the simultaneous determination of NiII and CoII; the metal ions were complexed with dimethylglyoxime and the complexes were adsorbed on the surface of a glassy carbon rotating disc electrode, which was pre-plated with mercury. The stripping step was carried out by using a square-wave potential–time excitation signal. An electrochemical cleaning of the mercury film was employed, enabling the same mercury film to be used for a series of measurements. The limits of detection were 12 ng l–1 for CoII and 14 ng l–1 for NiII(for 120 s preconcentration), the relative standard deviation was typically about 2–3%(at the 1.2 µg l–1 level) and linearity held for a concentration range of at least two orders of magnitude.