AnaZyst, February, 1967, Vol. 92, p . 137 I37 The Collection of Uranium (VI) on Cellulose Phosphate BY T. BRUCE AND R. W. ASHLEY (Atomic ETzergy of Canada Limited, Cltallz Rivev, Ontario, Canada) KEMBER~ has shown that the ion-exchange properties of cellulose phosphate can be used for the collection of minute amounts of cations dissolved in water. Campbell, Spano and Green2 have also reported the collection of trace amounts of various metals on ion-exchange resin-impregnated papers and their direct measurement on the paper by X-ray fluorescence. Cellulose phosphate paper can also be used to precipitate, from dilute aqueous solution, ions that form insoluble phos- phates. This property, together with X-ray fluorescence measurement, has been used to determine very low concentrations of uranium in pure aqueous solution.Solutions were passed through discs of Chromedia P81 (effective diameter of 1 cm) by using Kember’s technique. The discs were then dried in a desiccator over silica gel for about 16 hours and the X-ray fluorescence intensity measured. It was assumed that the uranium was held on the surface of the disc and only this side was counted. Solutions were prepared containing 0 to 100 pg of U(V1) in 10 ml of distilled water and treated as described. After correcting for the blank, a calibration graph was plotted for micrograms of uranium against counts per second, and the counting-rate was found to be proportional to the amount of uranium placed on the disc. The standard deviation a t the 95 per cent. confidence level was found to be & 3-5 pg of uranium, and the slope of the calibration graph was equal to 0.14.The procedure was tested as follows. A large volume of solution, containing 5Opg of uranium per litre, was prepared and 1-litre aliquots were taken for each test. The results obtained are shown below- Uranium added, pg . . . . 50 Uranium found, pg . . . . 50.5, 47.5, 49.5, 49-0 Mean, p g . . .. . . 49.1 Difference, pg . . .. -0.9 (-1.8 per cent.) These results show that uranium can be collected quantitatively on cellulose phosphate from solutions as dilute as 50 pg of uranium per litre. In a similar way, uranium was collected on discs of cellulose phosphate, placed in a spectro- fluorimeter and excited at 285 mp. The fluorescence intensity was measured a t 495 mp and found to be approximately proportional to the amount of uranium on the disc in the range 1 to 10 pg of uranium, and was then unaffected by increasing amounts of uranium.Cellulose phosphate fluoresces under the influence of the exciting light, producing a high blank value that makes quantitative measurement of uranium impossible. Washing with dilute phosphoric acid reduces, but does not eliminate, the blank fluorescence. This fluorescence technique can be used to identify uranium in very dilute solution, but jt is not suitable for quantitative work. This paper is an excerpt from CRDC-1250, a report issued by Atomic Energy of Canada Limited, entitled “Collection and Determination of Trace Amounts of Uranium Using Cellulose Phosphate Ion-Exchange Papers,” which is available to those interested in a fuller description of the experimental work, from Atomic Energy of Canada Limited. REFERENCES 1. 2. Kember, N. F., Analyst, 1960, 87, 449. Campbell, W. J., Spano, E. F., and Green, T. E., Analyt. Chem., 1966,38, 987. Received July 20th, 1966