Extraction-Spectrophotometric Determination of Molybdenum, Tungsten and Rhenium with Thiocyanate and Thioacetanilide

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Abstract
A procedure for extraction-spectrophotometric determination of Mo(VI), W(VI) and Re(VII) with thiocyanate and thioacetanilide (RSH) at trace level in the complex materials e.g. ores, steel, cement dust, coal ash and waste water is described. These metals in reduced state e.g. Mo(V), W(V) and Re(IV) react with thiocyanate and RSH to give benzene- extractable colored complexes with molar absorptivity in the range of (1.90-3.06)×104 l mol-1 cm-1 at λmax 410-470nm. The Mo and W determinations are free from interferences of the metals which are generally associated with them. The effect of various analytical variables on extraction of the metals, and the composition and the conditional extraction constants of the complexes are discussed.