Simultaneous Determination of Pb and Cd Traces in Water Samples by Anodic Stripping Voltammetry Using a Modified GC Electrode

The determination of Pb and Cd with a Nafion-modified glassy carbon electrode and Cu-DPABA complex (Cu-DPABA NA/GCE; DPABA is methyl 3,5-bis{bis-[(pyridin-2-yl)methyl]amino}methyl-benzoate) as an alternative electrode for anodic stripping voltammetry was described. Pb and Cd were accumulated in acetate buffer pH 4 at a potential of -1.4 V (vs. Ag/AgCl electrode) for 120 s followed by a DPASV scan from -1.2 to -0.2 V. Under optimum conditions the calibration curves were linear in the range of 4.8 x 10(-9)-5.0 x 10(-5) and 5.0 x 10(-9)-5 x 10(-5) molL(-1) for Pb and Cd, respectively. Detection limits were 1.8 x 10(-9) and 1.2 x 10(-9) mol L-1 for Pb and Cd, respectively. Different parameters and conditions, such as membrane ingredients, accumulation time, potential and pH value were optimized. A study of interfering substances was also performed. A significant increase in current was achieved at the modified electrode in comparison with the bare glassy carbon electrode. The validation of the proposed method was made by Pb and Cd determination in the certified reference material Groundwater CRM 610 (BCR, Community Bureau of Reference, Brussels, Belgium). The electrode was successfully applied for determination of Pb and Cd in river water with a high content of organic contaminants without any pretreatment.