THE DETERMINATION OF COPPER AT THIN-FILM ELECTRODES BY CONSTANT-CURRENT STRIPPING POTENTIOMETRY

A comparison of the determination of copper by constant current stripp ing potentiometry (CCSP) at mercury and gold films has been carried ou t. The preferred solution conditions for the mercury film study were d etermined to be 0.1M ammonium acetate at pH 4.5 and 0.1M HCl for the g old film study. The influence of chloride on the stripping signal was investigated and it was found that for the mercury film conditions, we ll-formed stripping signals could be obtained up to a chloride concent ration oi 0.5M which permitted the ready determination of copper in se awater. With the gold film, high chloride concentrations affected both the film stability and the glassy carbon surface and repeatable resul ts were difficult to obtain. The optimized CCSP methods were applied t o various aqueous samples including tap water, seawater, TCLP (acetic acid) extracts as well as TCLP extracts using groundwater and ocean wa ter. 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 eithe r a mercury or gold film is discussed.