Determination of selenium, copper, lead and cadmium in biological materials by differential pulse stripping voltammetry

A simple and rapid stripping voltammetric method is described for the determination of selenium, copper, lead and cadmium in a single sample solution. The method utilizes differential pulse cathodic stripping voltammetry for the determination of selenium and differential pulse anodic stripping voltammetry for the other three elements. The use of a deposition potential of -0.3 V vs. SCE allows the determination of selenium in the presence of interfering ions at 1000-fold concentrations. Subsequent oxidation of the selenium to the electro-inactive selenium(Vi) permits direct determination of the other three elements in the same solution. Application of the method to NBS bovine liver and some fish samples proved to be satisfactory. The limits of detection obtained by this method were 0.1 μg l^-1 for selenium, 0.5 μg l^-1 for copper and 0.01 μg l^-1 for lead and cadmium. Determination of the four elements takes about 90 min.