SPECTROPHOTOMETRIC DETERMINATION OF RHENIUM WITH ETHYL VIOLET

The use of ethyl violet as a reagent for the extraction and spectrophotometric determination of trace amounts of rhenium is advocated. In aqueous solution perrhenate and the reagent form a product which can be extracted by benzene and similar solvents. The use of toluene or xylene does not produce a colour as intense as benzene for the same amount of rhenium. The effects of several variables have been studied and the optimum conditions have been found. The extraction should be carried out from a tartrate solution at pH 7, and the absorptiometric measurement be made at 615 mμ. Beer's law is obeyed up to ca. 2.4 p.p.m, of rhenium in benzene. The apparent molar extinction coefficient is 9.10.10~4. The effects of diverse ions have been examined. Small amounts (3 μg) of rhenium can be determined in the presence of 0.3—6.0 mg of molybdenum.