Determination of Trace Vanadium Using Neutral Red by Catalytic Fluorimetry

A new kinetic fluorimetric method has been proposed for the determination of trace vanadium. The method is based on the catalytic oxidation of neutral red with potassium bromate in a phosphoric acid medium. The optimal kinetic conditions of experimentation have been studied. The optimal reaction temperature is 100 ℃ in boiling water. The optimal reaction time is 5 minutes. Flowing cold-water is chosen to stop the reaction. The linear range of the vanadium is 0.10～1.50 μg/L. The detection limit for vanadium is 0.049 μg/L. The proposed method suffers no interference from more than 20 foreign ions. The method had high sensitivity and high selectivity. This method has been applied to determine trace vanadium in flour and mineral water samples with satisfactory results.