抄録
Micro amount of uranium was determined by fluorimetric method using alkali carbonate fluoride fusion. The effect of various alkali carbonate fusing fluxes on the fluorescence intensity were investigated. The recommended procedure was as follows. One ml of sample solution was gently evaporated in a 10ml platinum crucible. To the dried residue, 1.00g of fusing flux (NaF-Na2CO3-K2CO3 1: 4.5: 4.5 or NaF-Na2CO3-K2CO3-LiF 3: 3.5: 3.5: 0.2) was added and the mixture was fused for a desired period (20 min) in an electric furnace kept at a required temperature (600-690°C). After fusing the bead was crushed to fine powder, packed in a sample dish (3 mm depth×17 mm in diameter) for fluorescence measurement, and then fixed with a quartz plate (1mm thick), to obtain a flat surface. The sample was excited with mercury line at 365nm and fluorescence intensity was measured at 558nm, using a uranine solution as the reference standard. By the present procedure, more than 0.005μg of uranium in 1g of flux could be determined within the error of ±1%. The procedure was applied to the determination of uranium in sea water, after uranium was separated and concentrated by the solvent extraction as uranyl oxinate. The uranium content in sea water was estimated to be 3.16±0.04 μgU/liter.
