EXTRACTION AND SPECTROPHOTOMETRIC DETERMINATION OF VANADIUM(V) WITH N-PHENYLCINNAMOHYDROXAMIC ACID AND AZIDE

Vanadium(V) was found to react with N-phenylcinnamohydroxamic acid (PC HA) in the presence of azide to form a bluish-violet complex of stoich iometry 1:2:1 (V:PCHA:N-3(-)). The complex was quantitatively extracte d into chloroform from 0.03-1.5 mol l(-1) hydrochloric acid. The spect rum of the complex exhibited an absorption maximum at 370 nm with mola r absorptivity of 9x10(3) mol(-1) cm(-1). The coloured system obeyed B eer's law in the concentration range 0.6-6 mu g ml(-1) of vanadium(V). The method was found to be precise with standard deviation of 1.3% fo r ten determinations of 4 mu g ml(-1) of vanadium(V). The effects of f oreign ions on the extraction and determination of vanadium(V) have be en studied and the method has been found to be highly selective. The m ethod has been applied to the determination of vanadium in steel and w ater samples with reasonable precision and accuracy.