Differential-pulse polarographic behaviour of selenium in the presence of copper, cadmium and lead

Abstract

A differential-pulse polarographic method for the determination of Se is described. The effect of Cu, Pb and Cd on the Se peaks was studied. In order to find a suitable medium, HClO₄(pH 1), 0.1 mol dm^–3 KNO₃(pH 4), a buffer solution of pH 4 (CH₃COOH—H₃BO₃—H₃PO₄), a buffer solution of pH 9 (NH₃—NH₄Cl) and 10% Na₂SO₃(pH 9.5) were studied. In NH₃—NH₄Cl and 10% Na₂SO₃ media the expected peak for SeO^2–₃ was not observed; however, the SeSO^2–₃ ion gave a peak at –800 and –600 mV, respectively. In addition, in the CH₃COOH—H₃BO₃—H₃PO₄ buffer solution of pH 4, SeO^2–₃ gave two peaks at –610 and –1310 mV. The detection limit for Se in a buffer solution (pH = 4) of CH₃COOH—H₃BO₃—H₃PO₄ was 1 × 10^–8 mol dm^–3. The method was applied to some environmental samples.