Determination of Trace Vanadium in Food with Dual-wavelength and Dual-indicator Catalytic Kinetic Spectrophotometry

A dual-wavelength dual-indicator catalytic kinetic spectrophotometric method for the determination of trace vanadium in 0.2 mol/L citric acid medium was studied.It was based on the catalytic effect of vanadium on the oxidation of ethyl violet and naphthol green B by potassium bromate.The absorbance of catalytic system and uncatalytic system were measured at 650 nm and 720 nm.Under the optimum conditions,the linear range of the determination of trace vanadium was 1.00~80.0 μg/L.The detection limit was 1.1×10-10 g/mL and the relative standard deviation(n=12) was 2.2% for 20.0 μg/L vanadium.The method was applied to the determination of trace vanadium in flour and rice with satisfactory results.