Studies on vanadium(IV) complexes of azoxine s dyes.
Comparative studies of the reaction of 7-arylazo-8-hydroxyquinoline-5-sulphonic acid (Azoxine S) dyes with vanadium(IV), show that 2:1 yellow, water-soluble complexes are formed over the pH range 2.5-6, and that the phenyl derivative is the most suitable for spectrophotometric determination of 0.2-1.4 ppm of vanadium(IV). The colour is formed instantaneously and is stable for about 8 hr. The molar absorptivity at lambda(max), 400 mmu;, is 1.15 x 10(4), and the equilibrium constant for complex formation is of the order of 10(2). These dyes can also be used as indicators in the direct complexometric determination of vanadium(IV). The interference of a number of anions and cations is reported.
Goyal
S S
SS
Chemical Laboratories, University of Rajasthan, Jaipur, India.
Tandon
J P
JP