A direct method for the determination of selenium and lead in cow's milk by differential pulse stripping voltammetry

The selenium and lead contents in milk samples from Turkey were determined using a hanging mercury drop electrode(HMDE) and differential pulse cathodi c stripping voltammetry (DPCSV) and differential pulse anodic stripping vol tammetry( DPASV), respectively. In this method, the milk samples were diges ted in HNO3 : HClO4 (1:1)mixture by a wet digestion procedure. The DPCSV of milk samples in 0.1 M HCl solution showed a peak for selenium at -0.56 V, and DPASV for lead showed a peak at -0.35 V. A deposition potential of -0.2 V for selenium, and -0.5 V for lead were suitable. The standard addition m ethod was used to determine selenium and lead in the sample. The linear dom ain range was 75-1.2 mu g/l for selenium with a correlation coefficient of 0.9981 and 185-8.7 mu g/l for lead with a correlation coefficient of 0.9945 . The proposed method provides a simple and suitable procedure for the dete rmination of trace amounts of selenium and lead. In this method, there is n o need for sophisticated instruments and tedious separation procedure. Sele nium and lead contents of milk samples from three distinct regions of Turke y were obtained between 21.5-69.4 and 22.1-59.2 mu g/l (n = 4-5), with the relative standard deviations of 10.3-10.7 and 6.8-9.9%, respectively. (C) 2 000 Elsevier Science Ltd. All rights reserved.