Determination of trace Vanadium(V) using catalytic kinetic spectrophotometry

A new catalytic kinetic spectrophotometry for determining trace amount of pentavalent vanadium ion was proposed.The method is based on the catalytic effect of Vanadium on the oxidation of neutral red by KBrO_3 in a medium of H_2SO_4 in the presence of ascorbic acid as an activator.The influence of measuring wavelength,medium,activator,temperature and time of reaction,and measured absorbance were tested.The optimum experimental conditions are as follows.The applied solution is composed of 0.5?mL neutral red of 1.00×10~(-3)?mol/L,1.2?mL sulfuric acid of 5×10~(-2)?mol/L,0.2?mL ascorbic acid of 5×10~(-3)?mol/L,1.2?mL potassium bromate of 1.00×10~(-2)?mol/L and trace amount of pentavalent vanadium ion.The(temperature and) time of reaction,as well as measuring wavelength are boiling point,16 minutes and 525 nm,respectively.The linear range for this determination method is 0.0～0.6??μg/L.The detection limit is 1.42×10~(-11)?g/mL.The RSD is less than 0.82%.The method has been used for the determination of trace Vanadium in lake water.The obtained recoveries is in the range of 96.0%～104.5%.