Abstract: Based on the catalytic effects of Vanadium (Ⅴ) on the discoloring reaction of methyl red  oxidized by KIO₄ and methyl red in a medium of citric acid,a new method for the determina- tion of vanadium by catalytic kinetic spectro-photometry was proposed.Linear relationship between log(A₀/A) and the concentration of vanadium is observed in the range of 0.64~3.2 μg/mL.The limit of detection is 3.75×10^-3 μg/mL.The proposed method has been used satisfactorily in the determination of vanadium in vanadium-extraction waste water.

Key words: Vanadium(Ⅴ);catalytic kinetic spectrophotometry;KIO₄ methyl red;vanadium-extraction , waste water