The spectrophotometric determination of uranium in ores, residues and other materials

Abstract

A spectrophotometric method, reported by Johnson and Florence, has been used for the determination of uranium in ores, residues, and other materials. The method makes use of the very sensitive chromogenic reagent 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (Br-PADAP) which gives a red complex with uranium at pH 7.6 for which X max - 578 nm. In the presence of a complexing solution containing (1,2-cyclohexylenedinitrilo)-tetraacetic acid (CyDTA), sulphosalicylic acid, and sodium fluoride, the only serious interference is caused by chromium (III), vanadium (V), and phosphate. By extraction of uranium into tri-n-octylphosphine oxide (TOPO)-cyclohexane solution the method becomes highly specific for uranium. A number of diverse uranium-containing materials have been analysed for uranium by this method l and the results are reported here. Comparison is made with results obtained by fluorimetric, X-ray fluorescence, and volumetric methods.