Constant current cathodic stripping potentiometric determination of arsenic on a mercury film electrode in the presence of copper ions Original Research Article

A method is described for the cathodic stripping potentiometric determination of arsenic on a mercury film electrode in 1 M HCl which contained copper (II) ions. Optimum determination of arsenic in this medium was accomplished with an electrolysis potential of −600 mV vs Ag/AgCl (1 M HCl) and application of a small constant reducing current (−1.5 μA) during the stripping step. As little as 2 μg/l of arsenic can be detected by this method in the presence of 5 mg/l copper (II) ions with an electrolysis time of 30 s. A linear concentration range of 10–200 μg/l was achieved under these conditions. Effective reduction of As(V) to As(III) in water, bovine liver and dogfish muscle samples was accomplished with l-cysteine prior to the CSP determination of arsenic.