Validation of electrochemical determination of zinc in selected pharmaceutical preparations.

A procedure of voltammetric (DP) determination of zinc in two selected pharmaceutical preparations was validated. The source of zinc in the first of them (Bio-Cynk) was the organic salt-gluconate, while the second (Zincteral) contained zinc sulfate. In order to transform zinc into solution, the samples of powdered tablets of each preparation underwent the extraction or mineralisation procedure. The concentration of zinc in solution was determined by differential pulse voltammetry (DP). In the validation process, the selectivity, accuracy, precision and linearity of DP determination of zinc in both preparations were examined. Zinc was determined within the concentration range of 1-20 ppm: the mean recoveries approached 98% in the case of Bio-Cynk and 100% for Zincteral; the errors of determination (RDS) were 2.98-11.5% for Bio-Cynk and 3.06-5.32% for Zincteral, respectively.