Spectrophotometric assay for the determination of total vanadium and the amp;plus;IV and amp;plus;V oxidation states of vanadium

摘要

A rapid colorimetric assay is provided for determining the concentration of vanadyl and vanadate ion species, and total vanadium concentration, in a sample. A sample suspected of containing vanadium in one or more of these oxidation states is combined with a colorimetric substrate that will provide for different absorption spectra with vanadyl and vanadate complexes. Suitable colorimetric substrates include halogenated hydroxyquinolines, e.g. broxyquinoline (DBHQ). The solvent and assay conditions are chosen to minimize oxidation of the vanadium. The absorbance of the sample is then read at two wavelengths, one that indicates the presence of both vanadyl and vanadate, and one that indicates the presence only of one species, generally vanadate. By comparison to a standard curve, the total concentration and the species concentration of vanadium in the sample is determined.