Differential pulse cathodic stripping voltammetric determination of selenium in pharmaceutical products.

The aim of this paper is to determine selenium from pharmaceutical products by differential pulse cathodic stripping voltammetry. Firstly, were established the optimum parameters for voltammetric determination of selenium (electrolyte, deposition time, pulse duration, pulse amplitude, etc.) and secondly, the content of selenium was determined in five pharmaceutical products. The drug samples were treated with a mixture of 6 ml HNO(3) and 1 ml H(2)O(2) in the microwave oven. Due to the matrix effects the method of addition is preferred. The peak potential is -0.545 V vs. Ag/AgCl, and the calibration curve is linear up to 0.125 ng/ml, but selenium was determined from pharmaceutical products used the calibration curve in the range 8-64 ng/ml, due to the concentration of selenium in these tablets.