Determination of trace vanadium in various waters by differential pulse adsorptive stripping voltammetry

Abstract

Abstract A sensitive voltammetric method is developed for the determination of trace amounts of vanadium in various water samples. The method is based on the preconcentration of the V V ‐2‐(5‐bromo‐2‐pyridylazo)‐5‐diethylaminophenol (5‐Br‐PADAP) complex at a potential of −0.5 V (vs. Ag/AgCl). The adsorbed complex is then reduced, producing a response with a peak potential of −0.8 V. The catalytic action of bromate ions on the reduction of the V V ‐5‐Br‐PADAP complex has also been investigated. The high catalytic currents obtained in presence of bromate ions are taken advantage of enhancing the sensitivity of the method. From the preliminary studies the optimal conditions for the determination of vanadium by differential pulse adsorptive stripping voltammetry have been established. The interference of various elements in this method has also been studied. The method of standard addition is employed in evaluating the concentration of vanadium in water samples. The determination limit is 20 ng/L and the RSD is 12% for vanadium concentrations of 500 ng/L.