The determination of copper at thin film electrodes by constant current stripping potentiometry

Abstract

A comparison of the determination of copper by constant cunrent stripping potentiometry (CCSP) at mercury and gold films has been carried out. The preferred solution conditions for the mercury film study were determined to be 0.1M ammonium acetate at pH 4.5 and 0.1M HCl for the gold film study. The influence of chloride on the stripping signal was investigated and it was found that for the mercury film conditions, well-formed stripping signals could be obtained up to a chloride concentration of 0.5 M which permitted the ready determination of copper in seawater. With the gold film, high chloride concentrations affected both the film stability and the glassy carbon surface and repeatable results were difficult to obtain. The optimized CCSP methods were applied to various aqueous samples including tap water, seawater, TCLP (acetic acid) extracts as well as TCLP extracts using groundwater and ocean water. Based on the results obtained for these various matrices, it was concluded that there are several advantages favoring the mercury film. The interference from organic components in the sample matrix on the general applicability of CCSP for the determination of copper at either a mercury or gold film is discussed.

Electrochemical Method for the Rapid on Site Screening of Cadmium and Lead in Soil and Water Samples

“…Quantifiable stripping peaks were obtained for all three analytes ( Figure 2). The broader and less well-defined Cu peak was considered due to the proximity of the Cu and Hg film oxidation potentials, irreversibility of the Cu 2+ reduction (Bradshaw & Scollary, 1997;Kadara et al, 2003) and the possible formation of insoluble Hg compounds, such as calomel, on the electrode surface due to the presence of Hg and chloride ions in the test solution (Jagner, Sahlin, & Renman, 1995;Nolan & Kounaves, 1999Zakharchuk, Saraeva, Borisova, & Brainina, 1999). This is reflected in the poorer correlation coefficient of 0.9970 achieved for Cu, as discussed below.…”