FLUORIMETRIC DETERMINATION OF URANIUM(Ⅵ) IN AQUEOUS SAMPLES WITH ITS PREVIOUS SEPARATION ON BARE SILICA

摘要

The fluorescence of uranium(Ⅵ) in phosphoric acid at 493 nm excited by a xenon high pressure lamp in continuous regime has been often recommended for the determination of uranium. In our studies, the medium of 0.5-2.5 mol.dm~(-3) phosphoric acid and the concentration interval of 0.5-4.0 mg.dm~(-3) of uranium(Ⅵ) has been found to be optimal for the determination. The usually used sulphuric acid in the mixture with phosphoric acid had a rather negative influence on the fluorescence intensity. Unfortunately, the fluorescence is negatively influenced by a number of interfering ions, complexing agents and surfactants. Thus, the previous separation of uranium(Ⅵ) is indispensable, for which the separation and pre-concentration of uranium(Ⅵ) on bare silica was optimized.