Highly selective and sensitive stripping voltammmetric determination of cobalt with ammonium 2-aminocyclohexene-1-dithiocarboxylate and nitrite

A sensitive stripping voltammetric determination of Co(II) is described, ba sed on the selective accumulation of its complex with ammonium 2-aminocyclo hexene-1-dithiocarbamate on HMDE and subsequent reduction of the complex in the presence of nitrite as a catalyst. The peak potential is about -1.35 V vs. Ag/AgCl reference electrode at pH = 10.0. The calibration graph was li near for the range of 0.01 - 40 ng/ml, with a limit of detection of 8.0 pg/ ml. The relative standard deviation for ten replicate analyses of 1.0 ng/ml of Co(II) is 2.6%. The method is very selective and has been applied for t he determination of cobalt in natural water and serum samples.