ADSORPTIVE PRECONCENTRATION FOR VOLTAMMETRIC MEASUREMENTS OF TRACE LEVELS OF VANADIUM IN THE PRESENCE OF COPPER

An electrochemical Stripping procedure for trace measurements of vanadium is described in which preconcentration is achieved by the adsorption of a vanadium-2-(2'-thiazolylazo)-p-cresol complex on a static mercury drop electrode. Cyclic voltammetry was used to characterize the interfacial and redox behavior. Optimum experimental conditions were found to be the use of a stirred acetate buffer (pH 4.2) solution with a 2(2'-thiazolylazo)-p-cresol concentration of 1.0 x 10(-5) M, a preconcentration potential of 0.00 V, a scan rate of 100 mV s-1 and a linear scan mode. The response is linear over the concentration range 5-30 mug V5+ l-1. For a 5-min preconcentration time, the detection limit is 3.9 nM. Possible interferences by anions and other trace metals were investigated. Sequential determination of copper with vanadium is possible. The method was applied to the analysis of mineral water.