Catalytic-adsorptive determination of vanadium in solutions of 2,3-dihydroxybenzaldehide and bromate-ions

The influence of bromate-ions on polarographic behavior of the complex of vanadium with 2,3-dihydroxybenzaldehide in acetate buffer solutions with pH 4.7–5.5 has been examined. Using alternating-current polarography, chronovoltammetry with linear sweep of potential, square-wave voltammetry it has been demonstrated, that the electrode process is complicated by adsorption of ligand and formed complexes of vanadium with ligand. In the presence of bromate-ions the analytical signal increases more than one order. A sensitive catalytic-adsorptive method has been developed for determination of vanadium. The vanadium complex accumulation has been carried out at the potential −0.2 V (saturated calomel electrode (SCE) – a reference electrode) in a solution with pH 5.4 in the presence of 5 × 10−5 М 2,3-dihydroxybenzaldehide and 0.1 М KBrO3. The detection limit for the accumulation time of 30 s is 2 × 10−10 М and the reduction current of vanadium complex is linear from 5 × 10−8 M to 5 × 10−10 М (the calibration graph is y = 1.5533x + 39.371 with correlation coefficient of 0.9998). The proposed method has been successfully applied to determination of vanadium in water samples of the Prut River (Republic of Moldova).