Iron(III) as activator for catalytic fluorimetric microdetermination of V(V).

The activation of the vanadium(V)-catalysed aerial oxidation of sodium 4,8-diamino-1,5 -dihydroxyanthraquinone-2,6-disulphonate by iron(III) is discussed. The oxidation product is intensely fluorescent and allows fluorescence-monitoring of the slow reaction, which is preceded by an induction period. On the basis of this investigation, an accurate method for determination of vanadium(V) at the 1-10 ng/ml level has been developed.