L'electrode a Pate de Carbone Modifiee Son Utilisation en Voltammetrie par Redissolution Anodique a Impulsions Differentielles en Presence d'Un Film de Mercure

Abstract

Abstract The various problems which are associated with the use of carbon paste electrode as thin mercury film electrode (TKFE) for anodic stripping voltammetry (ASV) can be overcame in a very easy and rapid way. The procedure consists to coat the carbon paste surface by spraying a graphite based conductive solution. For example, the dispersion of colloidal graphite in a mixture of methyl polymethacrylate with butyl acetate (as solvent) gives interesting results. Such a surface is easily renewable and the electrode does not require any pretreatment procedure like cleaning or polarization cycles…, after coating. The technique offers the advantage to limit the risk of sample contamination and memory effects. After pulverisation, a hard, uniform and compact layer is formed after evaporation of the solvent excess. The resulting electrode, electrochemically coated with mercury, exhibits a good stability as shown for the differential pulse anodic stripping voltammetry (DPASV) for cadmium ions. Replicate measurements were carried out in two different buffers at pH 8.5 and 5.0. Compared to the originally carbon paste electrode, a marked improvement of the reproducibility of the peak currents is observed. Calibration curves obtained by using the method of standard additions show a good linear relationship between cadmium ions concentration and peak current (down to 4×10−10 M.L−1). After a deposition time of 10 minutes, the detection limit for cadmium is 1×10−10 M.L−l in both media).