Simultaneous determination of cadmium and lead in medicinal plants by anodic stripping voltammetry

A simple method for the simultaneous determination of Cd and Pb in medicinal plants by differential pulse anodic stripping voltammetry, using a hanging mercury drop electrode, was developed. The pre-concentration of the metals was performed in 0.8 mol L−1 HCl at −0.73 V for 180 s. The sample preparation was carried out by dry-ashing 1.0 g of finely pulverized plant samples for 2.5 h at 500 °C. The determination limit of the method was 0.12 and 0.010 mg kg−1 for Pb and Cd, respectively. The method was applied to the quantification of cadmium and lead in samples of Hypericum perforatum, Mikania guaco, Mikania glomerata and Peamus boldus. The voltammetric method was shown to be useful for the control of contaminants in medicinal plants.