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 voltarrunetry has, been presented. The method is based on adsorptive accumulation of the complexes of Pb(II) and Zn(g) ions with dopamine onto hanging mercury drop electrode (HMDE), followed by reduction of the adsorbed species by differential pulse cathodic stripping voltammetry. Optimal conditions were obtained at: pH 9.5, dopamine concentration 8.0 x 10(-5) mol L-1, accumulation potential 0.0 V (vs Ag/AgCl), accumulation time 20 s, and scan rate 10 mVs(-1). Under the optimized conditions, linear calibration plots were obtained in Pb(II) and Zn(g) concentration ranges 5-150 and 5-250 ng mL(-1), respectively; detection limits were 0.07 ng mL(-1) for Pb(II) and 0.30 ng mL(-1) for Zn(II). The procedure has been successfully applied to the simultaneous determination of both ions in some real samples.