mg. of Al(II1) per 7 mg. of U(VI), and the N . S . Savannah type. The latter’s combination of interferences due to mole ratios of 0.7:l for Cr(II1) to U(VI), 1 . 5 : l for Fe(II1) to U(VI), and 0.3:1 for Ni(I1) to U(V1) in its dissolver solution demands very exact pretreatment of the sample to minimize their combined effects. Dissolver solutions of the d r m y Package Power Reactor type, which contain a 4 0 : l mole ratio of Fe(II1) to U(VI), and of the Consolidated Edison Reactor type, which contain a 17 : 1 mole ratio of Th(1V) to U(VI), were not amenable to the method. I n the latter solution, Th(1V) interferes in the 3M H2S04 with fuming by precipitating as Th(S04)2; when the 0.75M N a F is added, it interferes by precipitating as ThF4. This investigation indicates the need for the development of a cell assembly that withstands acid fluoride solution. Also, there is need for a supporting medium from which Fe(II1) and Al(II1)
do not precipitate. The medium Na6p3010 (6y0 w./v.)-NaF (sat.) was examined briefly; it appears to be promising. LITERATURE CITED
(1) Biggs, R. B., “Molten-Salt Reactor
Program, Semiannual Prog. Rept. for Period Ending Jan. 31, 1963,” U . S .
At. Energy Comm. Rept. ORNL-3419,
p. 127 (May 24, 1963). (2) G. L.. Holbrook.’ W. B.. \ , Booman. AXAL.~ H E M 31, . i 0 (1959). (3) Booman, G. L., Holbrook, W. B., Rein, J. E., Ibid., 29, 219 (1957). (4) Ginocchio, B. J., “Uranium, Automatic Potentiometric Ferric Sulfate Method,” Method Nos. 1 219224 and 9 00719224 (2-24-58); ORNL Master Analytical Manual, U . S . 9 t . Energy Comm. Rept. TID-7015, Sec. April 1958. (5) Goldstein, Gerald, ANAL.CHEM.36, 243 (1964). (6) Jones, H. C., “Automatic Coulometric Titrator, ORKL RZodel Q-2005, Electronic, Controlled - Potential,” Method Nos. 1 003029 and 9 003029 (R. 6-7-62); ORNL Master Analytzcal
Manual, U . S.At. Energy Comm. Rept. TID-7015, Suppl. 4, June 1962. ( 7 ) Kellev. R l . T.. Jones, H. C.. Fisher. D. J., A ~ A LCHEM. . 31 ,’488, 956 (1959):
(8) Shults, W. D., “Uranium, Automatic Controlled - Potential Coulometric *Method,” Method Nos. 1219225 and 9 00719225 (1-29-60); ORNL Master Analytical Manual, U . S. At. Energy Comm. Rept. TID-7015, Suppl. 3 June 1961. (9) Shults, W. D., Dunlap, L. B., Anal. Chim. Acta, 29, 254 (1963). (10) U.S. At. Energy Comm., “Proceedings of the AEC Symposium for Chemical Processing of Irradiated Fuels from Power, Test, and Research Reactors, Richland, Washington, October 20 and 21, 1959,” TID-7583, January 1960. (11) S’erheek. A. A,. Moelwvn-Hughes. ’ J: T., Verdier, E. T . , Anal. ?him. acta; 22, 570 (1960). (12) Zittel, H. E., Dunlap, L. B., A x . 4 ~ . CHEM.35, 125 (1963). (13) Zittel, H . E., Dunlap, L. B., Thomason, P. F., Zbid., 33, 1491 (1961). RECEIVEDfor review October 1, 1964. Accepted December 18, 1964. Research sponsored by the U. S. Atomic Energy Commission under contract with the Union Carbide Corp.
Determination of Uranium and Americium-Curium in Urine by Liquid Ion Exchange F. E. BUTLER Savannah River Planf, E. I. du Ponf de Nemours and Co., Aiken, S. C.
b Exchange of Th, Pa, U, Np, Pu, Am, Cm, and Cf from various concentrations of “ 0 3 and HCI to liquid ion exchangers was determined. Both anion and cation exchangers were used; the former was triisooctylamine (TIOA), while the latter was di-2ethylhexyl phosphoric acid (HDEHP). Tests with TIOA indicated preferential and rapid removal of U from other actinides, and in a mixture of Pu(lll) and Np(lV), N p was extracted to TIOA. The reagent also separated Pa233 from the parent NpZ3’. HDEHP extracted more than 90% of all eight actinides from an acid solution adjusted in the pH range 4 to 5. At higher acidities-e.g., 4N “ 0 8 all the actinides are extracted except Am, Cm, and Cf. Procedures were developed for analysis of U235and Am241-Cm244 in urine. Tracer recoveries were greater than 90% and decontamination factors were sufficiently high for other actinides. Detection limits by direct alpha counting were 0.3 d.p.m. for 250-mi. urine samples. Overall recoveries, through electrodeposition techniques, were 84 2 10% for UZ3jand 89 5 6% for Am241. 340
ANALYTICAL CHEMISTRY
A
to determine actinides separately and as mixtures are needed more as production of transplutonium elements increases. Liquid ion exchange is a relatively new technique for chemical analysis. With this technique, an aqueous sample and organic reagent dissolved in an inert solvent are thoroughly mixed. Xuclides as anions and cations are substituted at exchange sites in the immiscible organic phase, in a manner similar to absorption by solid ion exchangers (3, 4 ) . An advantage is the rapidity of both absorption and desorption of ions. A survey of the literature showed limited use of liquid ion exchange for analytical procedures, particularly for analysis of actinides in urine. Previous tests at the Savannah River Plant with H D E H P resulted in a method to separate Ca and Sr ( 2 ) . This reagent and TIOA were further studied to develop analytical techniques for the actinides T h through Cm. NALYTICAL METHODS
I
EXPERIMENTAL
Reagents. H D E H P from Union Carbide Chemical Co. was purified by washing with 4 N H X 0 3 and water
prior to use. TIOA from Bram Chemical Co. was not purified before use. TIO.A-xylene, lo%, and H D E H P toluene, 20%, were satisfactory dilutions for the reagents, and are henceforth referred to as TIOA and H D E H P . For exchange reactions, equal volumes of organic and aqueous solutions were used unless otherwise specified. Procedure. Actinides were tested separately with the anion and cation exchangers. Ten-milliliter samples of individual actinides were shaken vigorously for 1 minute and allowed to settle. Small aliquots of the aqueous samples were counted for alpha and/or gamma activity before and after exchange. No attempt was made to adjust actinide valences initially. Each spike solution was evaporated to dryness with the same acid used for dissolution in the test. RESULTS
Anionic Complex Formation (TIOA). Results of initial tests with TIOA and aqueous solutions are summarized in Table I , including the probable valence of each actinide. Only U23*and Pa233were removed from
3N HCl. Neptunium-237 exchanged quantitatively from 8N HC1. Am241, CmZ44, and Cf2j0-252 did not form exchangeable anionic complexes with HCl. Alpha counting indicated that Th232 did not absorb in TIOX from HC1. Gamma counting showed some removal of daughter products. Recounts of aqueous solutions following extraction showed buildup of gamma to the original activity within 1 to 2 days. The Th232 chain was probably broken a t Po216, based on this rapid buildup and the known exchange of the chloride complexes to anion resins ( 7 ) . Although there mas greater than 96% exchange of N:p237from 8N HCl and valence adjustPu239 from 4 N "03, ments were necessary to separate these two actinides. TIOA will absorb the chloride complex of Xp(IV), but not that of Pu(II1) (8). These valences were attained by reduction with either ammonium iodide (6) in concentrated (12.V) HCl or freshly prepared ferrous sulfamate ( 8 ) in 4iv HxOs. iifter this reduction, more than 95% of Np237 and less than 5y0of I'u239 exchanged to TIO.4. Table I shows a possible separation of ?J1P7 and its daughter Pa233. Further extractions of Kp237showed removal of 90% of l'a233 from 4.511; HC1 solution. More than 99% of Pa233was removed from solution in two extractions with TIO.4; no Kp237 was exchanged under these conditions. U23jand its daughter Th*31 were also separated by extraction of a 3.5N HCl solution with TIOA; the 0.084-m.e.1~. Th23l remained in aqueous solution. U2A5was completely stripped from TIOA in 1 minute with an equal volume of water. Cation Removal ( H D E H P ) . Results of initial tests with H D E H P are shown in Table 11. T h e rapidity of exchange of the actinides was demonstrated by removal of all Am241 from aqueous solution to H D E H P in approximately 1 second of vigorous shaking. More than 90% of all eight actinides were removed from the original sample to the organic phase from acid solution a t p H 4 to 5. Because H D E H P
Table 1.
Aqueous solution HC1 1N 25 3 s
4s
6S
8-I' HXOo 4 s
T ~ ~ I Y ) Paar3(V)
