Catalytic determination of vanadium in water

A kinetic determination of V(V) as a catalyst was spectrophotometrically performed by using the indicator reaction of Gallamine blue (GB⁺) and bromate at pH 2.0. The reaction was followed by measuring absorbance change for a fixed-time of 3 min at 537 nm. The variables such as reagent concentration, pH, buffer concentration, ionic strength and temperature were optimized to improve the selectivity and sensitivity. Under the optimized conditions, the determination of V(V) was performed in the range 1–100 μg L⁻¹ with limits of detection and quantification of 0.31 and 0.94 μg L⁻¹. The developed kinetic method is sufficiently sensitive, selective and simple. It was successfully applied to the speciative determination of total V and inorganic dissolved vanadium species, V(V) and V(IV) in environmental water samples. The oxidizing property of permanganate is used to differentiate between V(IV) and V(V) species. The V(IV) content was found by subtracting the V(V) content from those of total V. The recovery is above 95% for V(V) spiked samples. Additionally, the accuracy was validated by analysis of a certified water sample, CRM TMDA-53.3, and the results were in good agreement with the certified value.