The determination of copper, cadmium, and lead in sea water by anodic stripping voltammetry with a thin film mercury electrode

Abstract

The application of anodic stripping voltammetry to the determination of Cu, Pb, and Cd in acidified sea water samples has been examined. The analyses were carried out using a thin film mercury electrode prepared in situ by the method of Florence. The electrode was rotated in the collection step but held stationary in the stripping step. The stripping involved a linear DC potential ramp and background compensation was employed. Resolution of the stripping peaks required "curve fitting" of the baseline.In the acidified sea water electrolyte it was found that the Pb and Cd stripped to Pb(II) and Cd(II) while the Cu stripped to Cu(I). A good correlation was found between the stripping signals and predictions based on the Levich equation for deposition at a rotating disk electrode and the De Vries and Van Dalen equation for stripping from a thin film electrode. The effect of sample acidity was examined and it was concluded that in unpolluted, filtered sea water the total metal was free for analysis at pH 2. Calibration was by the method of standard addition and intercalibration studies showed that the results agreed well with those obtained by other methods.