The Determination of Zinc, Cadmium, Lead, Copper and Bismuth in Bottom Sediments of Sea and River by Anodic Stripping Voltammetry

Abstract

A method was described for the simultaneous determination of zinc, cadmium, lead, copper and/or bismuth in bottom sediments of sea and river by square wave anodic stripping voltammetry (SWASV) and differential pulse anodic stripping voltammetry (DPASV) with a hanging mercury drop electrode. Before the determination by ASV a wet mud was digested with a mixture of nitric and hydrochloric acids. An aliquot of acid-digested sample solution was taken and evaporated to near dryness on a hot plate and the residue dissolved in hydrochloric acid. This solution was heated after the addition of hydroxylamine hydrochloride to reduce iron= to iron(II), because iron (III) interfered with the measurement. Stripping curves of zinc, cadmium, lead and copper in this solution were recorded as well defined peaks. The peak potentials were0.93 V for zinc, -0.57 V for cadmium, 0.36 V for lead and - 0.11 V for copper (vs. SCE). The simultaneous determination of the four elements by ASV was accomplished by the standard addition method. The results obtained are in good agreement with those by atomic absorption spectrophotometry. When bismuth contained in sediments, it could also be determined satisfactorily by this method. A peak potential 0. O^2- V (vs. SCE) came out for bismuth.