A copper bismuth film electrode for adsorptive cathodic stripping analysis of trace nickel using square wave voltammetry

Stripping analysis has been widely recognised as a powerful tool for trace metal analysis. Its remarkable sensitivity is attributed to the combination of a preconcentration step coupled with pulse measurements that generates an extremely favourable signal-to-background ratio. Mercury-based electrodes have been traditionally employed for achieving high reproducibility and sensitivity of the stripping technique. However, because of the toxicity of mercury, new alternative electrode materials are highly desired, particularly for on-site monitoring. Recently, the use of bismuth thin films, deposited in situ on platinum or glassy carbon substrates, has been proposed as a possible alternative to mercury: bismuth is 'environmentally-friendly', with a low toxicity and a widespread pharmaceutical use. In this paper, the preparation of bismuth film electrodes by electrodeposition on a copper substrate and their adsorptive stripping performances are presented. Bismuth film electrodes were prepared ex-situ by pulsed potential electrodeposition. The analytical performances of these electrodes for adsorptive cathodic stripping voltammetry of nickel were evaluated in nondeacrated solutions. Well-defined peaks along with low background current were obtained in ammonia buffer by square wave voltammetry, using dimethylglyoxime as complexing agent. Linear calibration curves were obtained for Ni2+ concentrations ranging from 1 x 10(-8) to 1 x 10(-7) mol L-1 and from 1 x 10(-7) to 1 x 10(-6) mol L-1 with relative standard deviations of 5% (n = 15) at 1 x 10(-7) mol L-1 level. The analytical methodology was successfully applied to monitor Ni2+ content in industrial electrolytic baths, ground water and tap water. These results open the possibility to use bismuth film electrodes as an alternative to mercury-based electrodes for nickel analysis. (c) 2006 Elsevier B.V. All rights reserved.