Square wave anodic stripping voltammetric determination of Cd and Pb ions at a Bi/Nafion/thiolated polyaniline/glassy carbon electrode

A glassy carbon electrode modified with Bi, Nafion and 2-mercaptoethanesulfonate (MES)-tethered polyaniline (PANI) was applied to sensitively detect Pb2+ and Cd2+ by square wave anodic stripping voltammetry. The PANI-MES interaction was examined by quartz crystal microbalance and Fourier transform infrared spectrophotometry. The electrode modification of thiolated PANI exhibits a higher analytical sensitivity versus that of pristine PANI, because the coordination of Pb2+ and Cd2+ with S atoms in the thiolated PANI film can improve their preconcentration efficiencies. Under optimum conditions, the linear calibration curves ranged from 0.1 to 30 mu g L-1 for Pb2+ and 0.1 to 20 mu g L-1 for Cd2+, with limits of detection (S/N=3) of 0.05 mu g L-1 for Pb2+ and 0.04 mu g L-1 Cd2+, respectively, after their preconcentration at 1.2 V vs. SCE in pH 4.0 acetate buffer containing 200 mu g L-1 Bi3+ for 5 min. This method was successfully applied for analyses of Pb2+ and Cd2+ in real water samples. (C) 2011 Elsevier B.V. All rights reserved.