Determination of copper in seawater by anodic stripping voltammetry

Abstract

Copper in surface seawater has been determined using both hanging mercury drop and thin film electrodes. Total copper was found to be in the range 0.4–0.7 μg l −1, and labile copper in the range 0.2–0.4 μg l −1. Most of the copper present in seawater is complexed with or adsorbed on organic matter, and a smaller percentage is associated with inorganic colloids. Seawater contains both organic and inorganic compounds which will react with approximately 1×10 −8 M added ionic copper. Because of the presence of the complexing agents, peak current-copper concentration calibration curves in seawater are non-linear, and care must be exercised in using spiked results in the calculation of the copper content. The thin film electrode (TFE) is more suitable than the hanging mercury drop electrode for determining copper in seawater, although the TFE results are more dependent on deposition potential, and suffer from interference by nickel if very negative deposition potentials are used.