Synergic extraction and photometric determination of vanadium(5) with N-phenylacetylmandelohydroxamic acid in the presence of phenols

Vanadium(5) reacts with monobasic and bidentate extracting agent, N-phenylacetylmandelohydroxamic acid, to form 1:2 complex containing a basic V=O group and an acidic V-OH group in the same complex. The basic group reacts with acidic substances, like phenols to form addition compound in organic solvents, giving rise to a hyper- and bathochromic effect. On the basis of the high molar absorptivity of the resulting complex, a selective and sensitive method for the extraction and photometric determination of vanadium has been developed. The method has been fruitfully applied for the determination of trace amounts of vanadium in steels. Ti(4) and Zr(4) do not interfere. (author)