Selective stripping voltammetric determinations employing cells for electrolysis with simultaneous ion-exchange or solvent extraction

Cells have been designed for stripping-voltammetry analyses employing graphite working electrodes and mercury film electrodes on a graphite support, permitting ion-exchange or solvent extraction separation simultaneously with the pre-electrolysis. The ion-exchange separation was tested on the determination of mercury in the presence of excess of copper(II), lead and cadmium and on the determination of bismuth in the presence of excess of copper(II). The solvent extraction separation was tested on the determination of mercury(II) in the presence of copper(II), lead and cadmium and the determination of copper(II) in the presence of bismuth. Very good results were obtained by using ion-exchange, where the sensitivity and precision of the determination are comparable with those obtained in the determinations without separation, the separation efficiency being very high, limited virtually only by the capacity of the ion-exchanger used. The solvent extraction separations yielded poorer results: the sensitivity of the determination is decreased substantially, the separation efficiency is not very high and difficulties arise from the adsorption of the organic phase on the electrode surface.