Catalytic voltammetric determination of molybdenum at a chemically modified carbon paste electrode

Trace amounts of molybdenum can be determined in an acetate buffer solution (pH 2.6) containing chlorate, after the accumulation of molybdenum on a alpha-benzoinoxime modified carbon paste electrode, coupled with the catalytic effect on the reduction of chlorate. Under optimized conditions, the catalytic voltammetric procedure gives a detection limit of 20 nmol L(-1) molybdenum (60 s accumulation). Most of the ions investigated did not interfere with the determination of molybdenum except for stannous ion. The catalytic peak current increases linearly with molybdenum concentration between 0.1 and 80 mu mol L(-1) with a correlation coefficient of 0.997 and a current sensitivity of 2.13 mu A/mu mol L(-1). The chemically modified carbon paste electrode also displays good reproducibility with a relative standard deviation of 6.4 % for 20 repetitive determinations of 5.0 mu mol L(-1) molybdenum solutions.