Determination of Uranium by Packed-Column Supercritical Fluid Chromatography with 1-Phenyl-3-methyl-4-benzoylpyrazolin-5-one

A new procedure for the determination of uraniumby packed-column supercritical chromatography is proposed here. 1-Phenyl-3-methyl-4-benzoylpyrazolin-5-one (HPMBP) is chosen, as it can easily extract uraniumfrom a nitric acid aqueous phase in the presence of a synergistic agent. Eighteen columns packed with C18-grafted silica have been tested. Adding the chelating agent directly to the mobile phase greatly improves the elution peak shapes. Trioctylphophine oxide (TOPO), diphenyl sulfoxide, and phenanthrenehave been studied as synergistic agents. The influence of the injection solvent is also shown, and a calibration curve is obtained for uraniumin the range of 20 ng to 2 μg injected. The limit of detection is 2 μg of uranium. The accuracy of the method is 4%, and the repeatability measured (1σ) is 3%.