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

Abstract A glassy carbon electrode modified with Bi, Nafion and 2-mercaptoethanesulfonate (MES)–tethered polyaniline (PANI) was applied to sensitively detect Pb 2 + and Cd 2 + 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 Pb 2 + and Cd 2 + 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 μg L − 1 for Pb 2 + and 0.1 to 20 μg L − 1 for Cd 2 + , with limits of detection ( S / N  = 3) of 0.05 μg L − 1 for Pb 2 + and 0.04 μg L − 1 Cd 2 + , respectively, after their preconcentration at − 1.2 V vs. SCE in pH 4.0 acetate buffer containing 200 μg L − 1 Bi 3 + for 5 min. This method was successfully applied for analyses of Pb 2 + and Cd 2 + in real water samples.