FLUOROMETRIC-DETERMINATION OF URANIUM(VI) IN WATERS BY FLOW-INJECTION ANALYSIS AFTER PRECONCENTRATION ON A SILICA-GEL MICROCOLUMN

A method was developed for the selective determination of trace concentrations of uranium(VI) by flow-injection analysis (FIA) with fluorimetric detection. Uranium(VI) is selectively separated and/or pre-concentrated from a volume up to 20 ml on an activated silica gel microcolumn (2 x 40 mm) from a medium of 0.03M EDTA, 0.06M tartrate, and/or 0.05M NaF at pH = 9.3. After washing the column the uranium is eluted with a mixture of 1.33M sulphuric and phosphoric acids and determined with a relative standard deviation not exceeding 6% for concentrations in the range 10-250-mu-g/l. The detection limit was estimated to be 0.1-0.2-mu-g of uranium. The method has been verified on artificial water samples with high content of the interfering elements and applied to analysis of waste and natural waters.