6-Chloro-3-hydrox y-2- [2 '-(5 '-methylfuryl)]-4<i>H</i>-chromen-4-one as an analytical reagent for the spectrophotometric determination of tungsten(VI)

Abstract

A 1:2 light yellow complex of tungsten (VI) is formed with 6-chloro-3-hydroxy-2 –[2'-(5'-methylfuryl)]<i>-</i>4<i>H </i>-chromen-4-one (CHMFC) in 0.18-0.32 <i>M </i>HClO₄ medium. The complex is extractable into chloroform and absorbs maximally at 4:15 nm. The absorbance remains constant for more than 1 h with molar absorptivity, detection limit and Sandell’s sensitivity as 2.16×10⁴ L mol^-1 cm^-1, 0.131μg mL^-1 and 0.0085 μg W cm^-2, respectively. Beer's law is obeyed in the concentration range of 0-2.6 μg W mL^-1 the correlation coefficient is, <i>r</i>=1.001, Oxalate interferes in the tungsten determination. The method has been satisfactorily applied to the analysis of tungsten in various synthetic and technical samples.