Simultaneous determination of Pb(ii) and Cd(ii) using an electrode modified with electropolymerized thiadiazole film

Abstract

The present study reports a sensitive electro-analytical method for the simultaneous determination of trace lead (Pb(II)) and cadmium (Cd(II)) using a non-mercury electrode modified with the electropolymerized thiadiazole film. The electropolymerization of 2,5-dimercapto-1,3,4-thiadiazole on a glassy carbon electrode is carried out, and differential pulse anodic stripping voltammetry for the simultaneous determination of trace Pb(II) and Cd(II) is developed by using this modified electrode as the working electrode. In 0.1 mol L⁻¹ acetate buffer solution at pH 5.5, the stripping peak currents after enrichment at −1.20 V for 300 s showed good linear relationships with Pb(II) and Cd(II) at concentration ranges of 1.00–200 and 0.50–200 μg L⁻¹, and the detection limits are 0.30 and 0.05 μg L⁻¹, respectively. The proposed method is applicable to the simultaneous determination of trace Pb(II) and Cd(II) in real water samples with the relative standard deviations of less than 5.7% and the recovery rates of 97.6–106%. The good response of the prepared electrode to Pb(II) and Cd(II) is attributed to the binding of thiol groups and the electrostatic interaction between the modified electrode with metal ions. The findings indicate that the proposed method is helpful in monitoring toxic elements in environmental waters.