Voltammetric trace metal determinations by cathodic and anodic stripping voltammetry in environmental matrices in the presence of mutual interference

Arsenic(III), selenium(IV), copper(II), lead(II), cadmium(II), zinc(II) and manganese(II) have been determined in environmental matrices by differential pulse cathodic (DPCSV) and anodic (DPASV) stripping voltammetry. The voltammetric measurements were carried out using, as the working electrode, a stationary mercury electrode, and a platinum electrode and a Ag ∣ AgCl ∣ KCl(sat) electrode as the auxiliary and reference electrode, respectively. An ammonia+ammonium chloride buffer of pH 9.0 was employed as the supporting electrolyte. The analytical procedure was verified by the analysis of the standard reference materials: Sea Water BCR-CRM 403, Estuarine Sediment BCR-CRM 277, Ulva Lactuca BCR-CRM 279 and Mussel Tissue BCR-CRM 278. The precision and accuracy, expressed as relative standard deviation and relative error, respectively, were lower than 5% in all cases, while the detection limit for each element was around 10−9 mol l−1. In the presence of high reciprocal interference, the standard addition method considerably improved the resolution of the voltammetric technique. The analytical procedure was transferred and applied to samples drawn in the Goro Bay (Ferrara, Italy).