catalytic spectrophotometric determination of vanadium (iv) based on the oxidation of alkali blue by potassium bromate

a simple, rapid and sensitive spectrophotometric method has been proposed for the determinationof vanadium (iv). the method is based on the catalytic effect of v (iv) on the oxidation of alkali blue bypotassium bromate at ph 4. the rate of decrease in the absorbance of alkali blue (at 572 nm) wasproportional to the concentration of v (iv) in the range of 100-6000 ng ml-1. the detection limit was 40 ngml-1. the proposed method shows a good selectivity for v (iv) over a wide variety of interference species. itis also valuable in that the presence of a 400 fold excess of v (v) can be tolerable, contrary to many methodsfor the determination of v (iv) which suffer from severe interference of v (v). this method was successfullyapplied to the determination of v (iv) in river water, alloy samples and several synthetic samples.