ANODIC-STRIPPING VOLTAMMETRIC DETERMINATION OF VANADIUM(V) USING A CARBON-PASTE ELECTRODE MODIFIED IN-SITU WITH CETYLTRIMETHYLAMMONIUM BROMIDE

A method for the voltammetric determination of vanadium(v) using a car bon paste electrode in situ modified with cetyltrimethylammonium bromi de (CTAB) is described. Vanadium is preconcentrated at the electrode s urface via its anionic oxalate complex from acidic solution (0.01 M ox alic acid, 0.25 mM CTAB, pH 2.2) at a potential of -0.9 V [vs. the sat urated calomel electrode (SCE)]. Simultaneously during accumulation, v anadium(v) in the complex is reduced to its tetravalent state. Differe ntial pulse anodic stripping voltammetry exploiting the reoxidation ca n be used for the determination of trace levels of vanadium(v). Linear ity between current and concentration exists for a range of 5 to 200 m u g.L-1 V-v with a preconcentration time of 1 min. The limit of detect ion (calculated as 3 sigma) is 0.07 mu g.L-1 with a preconcentration t ime of 10 min.