Differential pulse cathodic stripping voltammetric investigation of CrO42–, MoO42–, WO42– and VO3–

Abstract

The differential pulse cathodic stripping voltammetric behaviour of CrO₄^2–, MoO₄^2–, WO₄^2– and VO₃^– has been investigated and applied to the determination of trace concentrations of these oxyanions. Detection limits of 5.6 × 10^–7, 6.1 × 10^–8, 1.1 × 10^–7 and 8 × 10^–8M and quantitation limits of 1.87 × 10^–6, 2.03 × 10^–7, 1.1 × 10^–6 and 2.7 × 10^–7M have been calculated for the cathodic stripping voltammetric determination of CrO₄^2–, WO₄^2–, MoO₄^2– and VO₃^–, respectively. The effects of equimolar and lower concentrations of selected cationic and anionic interferents on their differential pulse cathodic stripping voltammetric behaviour have also been examined. These reveal that certain heavy metal cations such as Pb^II, Cu^II, Zn^II, Cd^II and Ag^I can compete with Hg^I for the appropriate oxyanions and that anions such as S^2– and l^–, which form partially insoluble mercury salts, can compete for sites around the mercury drop.