Adsorptive stripping voltammetric determination of cobalt in the presence of dimethylglyoxime and cetyltrimethylammonium bromide.

A sensitive procedure for determination of micro-traces of Co(II) by adsorptive stripping voltammetry is proposed. The procedure exploits the enhancement of the cobalt peak obtained by use of the system Co(II)-dimethylglyoxime-piperazine-1,4-bis(2-ethanesulfonic acid)-cetyltrimethylammonium bromide. Using the optimized conditions, a detection limit (based on the 3 sigma criterion) for Co(II) of 1.2 x 10(-11) mol L(-1) (0.7 ng L(-1)) was achieved. The calibration plot for an accumulation time of 30 s was linear from 5 x 10(-11) to 4 x 10(-9) mol L(-1). The procedure was validated by analysis of certified reference materials and natural water samples.