Catalytic stripping voltammetry of vanadium in the presence of dihydroxynaphthalene and bromate

Vanadium was complexed with 2,3-dihydroxynaphthalene (DHN), absorbed onto a hanging mercury drop electrode, and measured using square wave stripping voltammetry. The reduction current of the adsorbed complex was greatly increased (100 times) by the addition of bromate ion. Preconcentration of the vanadium complex was done at a potential of −0.1 V vs. AgAgCl at pH 4.8 in the presence of 0.1 M DHN and 5 mM NaBrO3. The detection limit for a 1 min adsorption time was 1.5 × 10−11 M, and the reduction current was linear over the range of 5 × 10−11 to 4 × 10−9 M. The relative standard deviation was calculated as 1% (n = 7) for 1 × 10−9 M. The method was applied to the determination of vanadium in natural water samples.