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 uranium by packed-column supercrit ical chromatography is proposed here. 1-Phenyl-3-methyl-4-benzoylpyrazolin- 5-one (HPMBP) is chosen, as it can easily extract uranium from a nitric aci d aqueous phase in the presence of a synergistic agent. Eighteen columns pa cked with C18-grafted silica have been tested. Adding the chelating agent d irectly to the mobile phase greatly improves the elution peak shapes. Trioc tylphophine oxide (TOPO), diphenyl sulfoxide, and phenanthrene have been st udied as synergistic agents. The influence of the injection solvent is also shown, and a calibration curve is obtained for uranium in the range of 20 ng to 2 mug injected. The limit of detection is 2 mug of uranium. The accur acy of the method is 4%, and the repeatability measured (1 sigma) is 3%.