Determination of cadmium by differential pulse adsorptive stripping voltammetry in the present of captopril

A new method is presented for determination of cadmium based on cathodic adsorptive stripping of the complex of cadmium with captopril,1-[(2S)-3-mercapto-2-methylpropionyl]-L-praline (CPL) at a hanging mercury drop electrode(HMDE). The most suitable operating conditions and parameters, such as pH, deposition potential, deposition time, ligand concentration, and others were selected and the determination of cadmium from aqueous solutions using the standard additions method was possible. Under the optimum conditions and for an accumulation time of 60 s, the measured peak current is proportional to the concentration of cadmium over the range of 1 - 300 nM. The limit of detection at S/N ratio of 3 was 0.3 nM and a relative standard deviation of 2.5% at 0.1 mu M was achieved. The interference of other cations and anions was studied. The method was designed in order to determination of Cd in four analytical grade salts, with satisfactory results.