Simultaneous determination of lead,copper, cadmium and zinc in pure zirconium metal by differential-pulse anodic stripping voltammetry

Zirconium metal (ca. I g) was dissolved in hydrofluoric acid, excess of which was removed by fuming with sulphuric acid. An aliquot of this solution was treated with sodium citrate and adjusted to pH 4.5. Lead, copper and cadmium were deposited on the hanging mercury drop electrode by applying a potential of ?0.8 V vs. Ag/AgCl for 1 min and anodic stripping voltammograms were recorded; the anodic peaks appeared at ?0.51, ?0.14 and ?0.67 V, respectively. In a separate run, zinc was deposited at ?1.2 V and the stripping peak appeared at ?1.1 V. Standard additions were used to quantify these impurities at levels in the low mg kg^?1 range, with relative standard deviations of 5–11%.