A Spectrophotometric Method for the Determination of Trace Vanadium Based on the Vanadium-Methyl Violet Reaction

Vanadium reacts with methyl violet in the presence of NH₃ to form a violet a complex. The ion association complex exhibits maximum absorption at 580 nm with an apparent molar absorptivity of 2.5×10⁷ L/(mol·cm). The molar ratio of the components of V(Ⅴ):MV=1:3. Beer's law is obeyed in the range of 0～6.4 μg/L for vanadium. It has been applied easily for the determination of V(Ⅴ) in water, flour, rice and mineral samples with satisfactory results.