Electrochemical Determination of Lead and Cadmium Traces in Zinc Oxide and Magnesium Stearate Used as Pharmaceutical Products

Abstract

Trace amounts of cadmium and lead were determined in zinc oxide and magnesium stearate by differential pulse anodic stripping voltammetry (DPASV) at hanging mercury drop electrode. Measurements were performed on zinc oxide samples without previous treatment whereas magnesium stearate samples were digested at 400ºC for 12 h. The mean recoveries were more than 95 %. Detection limits for cadmium and lead were 0.1 and 0.2 ppb, respectively, for deposition time of 90 s. The precision (RSD %, n = 10) for 5 ppb of the metals were below 6 % with the correlation coefficient of 0.997.