Simultaneous Determination of Trace Amounts of Lead and Zinc by Adsorptive Cathodic Stripping Voltammetry

A selective and sensitive method for simultaneous determination of lead and zinc by adsorptive differential pulse cathodic stripping voltammetry is presented. The method is based on adsorptive accumulation of the complexes of Pb (II) and Zn(II) ions with Dopamine onto hanging mercury drop electrode (HMDE), followed by reduction of adsorbed species by differential pulse cathodic stripping voltammetry. Optimal conditions were obtained at pH 10.0, Dopamine concentration of 1.0×10 M, accumulation potential of 0.0 V (vs. Ag/AgCl), accumulation time of 10 s, scan rate of 10 mV/s. Under the optimized conditions, a linear calibration curve was established for the concentration of Pb (II) and Zn (II) in the range of 5150 and 5-250 ng/mL, respectively, with a detection limit of 0.5 ng/mL Pb (II) and 1.8 ng/mL Zn (II). The procedure was successfully applied to the simultaneous determination of both ions in some real samples.