5,7-ジクロルオキシンによるイットリウムのケイ光定量ゼノタイム中のイットリウムの定量

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Optimum conditions for the fluorometric determination of yttrium by 5, 7-dichlorooxine was investigated, and the method was developed to the direct determination of yttrium in xenotime ore. Some 250500 mg portion of an ore sample was treated for 23 hours with 3040 ml of hot concentrated H2SO4. The solution was diluted to 50100 ml with water, and any insoluble residue was filtered. Sixty ml of 1 N oxalic acid was added to the solution and the pH was adjusted to 2.2. After standing for several hours, the precipitate was ignited to obtain the total amount of rare earths oxide, from which was weighed out 2550 mg. It was dissolved in HCl and diluted with water to adjust the concentration to 10 μg total rare earths oxide per ml. A 0.51.0 ml portion of the solution was transferred to a 100 ml beaker. To it were added 0.25 ml of 0.2% 5, 7-dichlorooxine, 20 ml of water and 5 ml of 20% NH4Cl solution. The yttrium-chelate was extracted with 25 ml of chloroform at pH 9.5, and the fluorescence intensity of the extract was measured. Yttrium contents of xenotime and fergusonite samples were 20.2929.81% as Y2O3.
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