Determination of sub-μg l −1 concentrations of copper by anodic stripping voltammetry at the gold electrode

Abstract

A rotating disc gold electrode is used for the determination of copper in μg l −1 and sub-μg l −1 concentrations without removal of oxygen by the method of subtractive anodic stripping voltammetry (SASV). The detection limit for a 90 s electrodeposition is 0.2 nM. The reduction and stripping of copper on gold under the SASV conditions are underpotential deposition/dissolution phenomena. A uniformly distributed submonolayer of copper, occupying 0.01–5% of the real surface of the electrode, is formed. Linearity in calibration plot is obtained up to 5% electrode coverage; in terms of the experimental parameters of the deposition step (rate of rotation and time of electrolysis), this condition for linearity is C Cu 2+ N 1/2t d ≤7×10 5 nM rpm 1/2 s . The bulk and underpotential deposition of Cu 2+ have been characterized in the supporting electrolyte used (10 mM HNO 3 and 10 mM NaCl). The analysis of copper in drinking and in sea waters has been performed.