Development of a polypyrrole-based amperometric detector for the determination of certain anions in water samples

The development of a polypyrrole-based modified electrode for use in the detection of anions in flow-injection analysis and ion chromatography is described. Chloride, nitrate, nitrite, perchlorate, bromide, carbonate, sulphate and phosphate were detected by using flow-injection analysis combined with the polypyrrole-based CME electrochemical detector. All of the anions were detected conveniently and reproducibly over a linear concentration range 1-100 mug/ml. A detection limit of 0.1 mug/ml was obtained for chloride and a limit of 1.0 mug/ml for all of the other anions. Chloride, nitrate, sulphate and phosphate, following separation using ion chromatography, were detected simultaneously by using a conductivity detector and the polypyrrole-based CME electrochemical detector in series. Both methods of detection yielded similar results with comparable sensitivity, linearity and limits of detection. This method was then applied to the analysis of fresh water samples. The electrode was stable over a 2-week period of operation with no evidence of chemical or mechanical deterioration.