Direct Quantitative Determination of Total Arsenic in Natural Hotwaters by Anodic Stripping Voltammetry at the Rotating Lateral Gold Electrode

A simple, rapid, selective and sensitive differential pulse anodic stripping voltammetric (DPASV) technique for the direct quantitative determination of inorganic total arsenic in natural hotwater was developed. The electrochemical determination of total arsenic has been carried out at the novel rotating lateral gold electrode in hydrochloric acid solution (37 % w/w). The analysis was performed with a special gold electrode whose active surface was located on the side. Reproductivity of measurement was achieved by the conditioning of the gold electrode. This was done every day before the measurements as well as when the background current varied strongly from measurement to measurement. The determination limit of 0.5 μg L-1 was achieved with 10 mL sample solution. The total arsenic concentration was made by appropriate selection of the deposition potential. During the deposition step, the total arsenic content was reduced at -1200 mV by nascent hydogen to As°. During the subsequent voltammetric determination, the preconcentration As° was again oxidized to determine the level. The method was applied successfully to the direct quantitative determination of total inorganic arsenic in hotwater. In order to show the accuracy of the results developed from voltammetric technique, the values obtained were compared with those obtained from inductively coupled plasma mass spectrometry (ICP-MS).