Spectrophotometric determination of uranium(VI) with benzyol-m-nitroacetanilide and application to uranium ores

The yellow coloured UO22+-bis-benzoyl-m-nitroacetanilide complex was extracted in isobutylmethyl ketone from solutions of Ph 5.5 to 7.0 and the metal was determined by measuring the absorbance of the extract at 395 nm (for 50-300μg of U) or at 415 nm (U, above 300 μg) with relative standard deviation of +- 1.01%. The presence of Ag+ and Tl+ did not interfere while magnesium-EDTA was used to mask Pb2+, Bi,3+, Cu2+, Cd2+, Al3+, Ga3+, In3+, Cr3+, Fe3+, Ni2+, Ba2+; Sr2+, Ce3+, Th4+, VO2+, MoO42-, and CrO42-. For Co2+, Be2+ and Zr4+ sulphosalicylic acid was used as the masking agent and iodide for Hg2+. The uranium content of several ores containing 2-25 percent of this metal has been determined with an average relative error of +- 1.3%. The dissociation constant of the complex was found to be 1.53 x 10-12. (author)