Determination of mercury and copper in waste water by anodic-stripping voltammetry at the gold electrode

A simple and highly reliable subtractive anodic stripping voltammetric method (SASV) for the determination of Hg²⁺ and Cu²⁺ in waste water using a gold rotating disc electrode is reported. The analysis is performed without removing oxygen. The stability of the electrode is excellent without requiring frequent electrochemical pretreatment or mechanical polishing. A simple wet digestion procedure is applied for destroying the organic matter. The method is applied successfully also in the presence of large excess of Cu²⁺ (up to 50000-fold excess) even when Hg²⁺ and Cu²⁺ are simultaneously deposited on gold. No evidence for intennetallic mercury-copper compounds was found. The absence of interference by the copper in such extreme conditions is explained on the basis of the underpotential deposition (UPD) phenomenon.