Voltammetric determination of 2-nitrophenol at a bentonite-modified carbon paste electrode

A bentonite-modified carbon paste electrode has been applied to the determination of 2-nitrophenol by differential pulse voltammmetry. The electrochemical reduction of 2-nitrophenol at - 0.8 V is carried out in an artificial sea water-formic acid/sodium formate medium at pH 4. The peak height was found to be dependent on the pH over the range 2-11; the presence of a secondary process was observed in the pH range 8-11. The peak potential showed a dependence on pH, with two linear regions with different slopes. A. linear relationship between peak intensity and concentration was obtained in the range 0.07-10 mg l(-1), with a detection limit of 0.03 mg l(-1) and a coefficient of variation of 1.3% at 5 mg l(-1). The effects of organic and inorganic species on the 2-nitrophenol determination were studied with a view to testing the resolution of the voltammetric technique. The proposed method has been applied to sea water samples with good results.