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 carbon paste electrode in situ modified with cetyltrimethylammonium bromide (CTAB) is described. Vanadium is preconcentrated at the electrode surface via its anionic oxalate complex from acidic solution (0.01 M oxalic acid, 0.25 mM CTAB, pH 2.2) at a potential of -0.9 V [vs. the saturated calomel electrode (SCE)]. Simultaneously during accumulation, vanadium(v) in the complex is reduced to its tetravalent state. Differential pulse anodic stripping voltammetry exploiting the reoxidation can be used for the determination of trace levels of vanadium(v). Linearity between current and concentration exists for a range of 5 to 200 mu g.L-1 V-v with a preconcentration time of 1 min. The limit of detection (calculated as 3 sigma) is 0.07 mu g.L-1 with a preconcentration time of 10 min.