Determination of traces of cobalt in the presence of nioxime and cetyltrimethylammonium bromide by adsorptive stripping voltammetry.

A sensitive method of Co(II) determination by adsorptive stripping voltammetry is presented. The method exploits the enhancement of cobalt peak current observed in the system Co(II)-nioxime-cetyltrimethylammonium bromide-piperazine-N,N'-bis(2-ethanesulfonic acid). The calibration plot for an accumulation time of 60s is linear from 5 x 10(-11) to 3 x 10(-9)molL(-1). The relative standard deviation is 3.8% for Co(II) determination at concentration 1 x 10(-9)molL(-1). The detection limit is 1.7 x 10(-11)molL(-1). The validation of the method is performed by the analyses of certified reference materials and comparing the result of Co(II) determination in river water sample by the proposed method with those obtained by ET AAS. The main advantage of this new system is the micro-trace Co(II) determination by adsorptive stripping voltammetry, as compared to those described before, a low concentration of the supporting electrolyte used, and so commercially available reagents without additional purification can be used.