ISO 7100:1983

Phosphoric acid for industrial use (including foodstuffs) — Determination of vanadium content — Phosphotungsten vanadate spectrometric method

A yellow complex is formed by reaction of the vanadium present in a test portion with phosphoric acid and sodium tungstate in acid medium. The spectrometric measurement of the absorbance is carried out at a wavelength of about 425 nm. The method is applicable to products having a vanadium content equal to or greater than 3 mg/kg.