A highly sensitive and selective spectrophotometric determination of vanadium(V) using 6-Chloro-3-hydroxy-7-methyl-2-(2-thienyl)-4H-chromen-4-one

A simple, rapid, highly sensitive and selective method for the extractive spectrophotometric determination of micro amounts of vanadium(V) has been worked out using 6-chloro-3-hydroxy-7-methy1-2-(2-thienyl)-4H-chromen-4-one (CHMTC) as a complexing agent in a weakly acidified (HCl, pH 0.84 - 1.09) medium. The greenish-yellow complex is quantitatively extractable into carbon tetrachloride, and shows maximum absorbance at 417 - 425 nm. The method obeys Beer's law up to 0.9 mu g V ml(-1), having molar absorptivity and Sandell's sensitivity of 8.26x10(4) dm(3) mol(-1) cm(-1) and 0.0006 mu g V cm(-2), respectively. As many as 39 cations and 14 anions and/or complexing agents do not interfere. The method has good reproducibility and can be satisfactorily applied to the determination of vanadium in steels, reverberatory flue dust and water samples.