Extraction and spectrophotometric determination of vanadium(V) with 8-hydroxyquinoline

Abstract

The extraction and spectrophotometric determination of vanadium (V) with oxine is investigated at higher acidities than described previously. Under these conditions, n-butanol and other alcohols are found to exert a synergic effect on the extraction of vanadium into benzene. In the presence of alcohol only a 6-fold ligand excess is needed for quantitative extraction in a single operation, the acidity of the aqueous medium being 0.05 M with respect to sulphuric or phosphoric acid. The interference of iron(III) in the spectrophotometric determination of vanadium is suppressed by the addition of pyrophosphate. Beer's law is obeyed up to 14.0 μg of vanadium/ml and the sensitivity is 0·008 μg of vanadium/cm 2 at 390 mμ. The composition of the extracted species is found to be vanadium:oxine:n-butanol = 1:2:2.