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

A method is described for the cathodic stripping potentiometric determinati on of arsenic on a mercury film electrode in 1 M HCl which contained copper (II) ions, Optimum determination of arsenic in this medium was accomplishe d with an electrolysis potential of -600 mV vs Ag/AgCl (1 M HCl) and applic ation of a small constant reducing current (-1.5 mu A) during the stripping step. As little as 2 mu g/l of arsenic can be detected by this method in t he presence of 5 mg/l copper (II) ions with an electrolysis time of 30 s. A linear concentration range of 10-200 mu g/l was achieved under these condi tions. Effective reduction of As(V) to As(III) in water, bovine liver and d ogfish muscle samples was accomplished with L-cysteine prior to the CSP det ermination of arsenic. (C) 1999 Elsevier Science B.V. All rights reserved.