805
Anal, Chem. 1084, 56,605-608
matograms of river water and rainwater are shown in Figure 2. River water and effluent were distilled and measured colorimetrically ( I I ) , and rainwater was directly measured by the colorimetric method (18) after filtration with a Millipore filter. It was found that there was a close relationship between our HPLC method (X)and the colorimetric one (Y), showing the following relation: log Y = 0.982 log X - 0.129, r = 0.986 on river water; log Y = 0.964 log X , r = 0.995 on effluents, and log Y = 1.075 log X - 0.073, r = 0.993 on rainwater. The concentration measured by our HPLC method was higher than that of the distillation-colorimetric method. But 3 of 106 river water samples showed much higher concentrations by the distillation-colorimetric method than those obtained by our HPLC method in spite of the fact that the levels were within the detectable limit. Those results showed that it was difficult to distill at a same distillation rate of 6-10 mL/min with distillation sets as defined (11). So, each distillation set having different rates gave a different recovery of ammonia gas into sulfuric acid or boric acid solution. The river water samples were sampled after heavy rain and consequently contained a very high amount of solid matter suspended in water, over 300 Mg/mL. The ammonium, combined to the surface of the matter, might be released during the course of the distillation step resulting in an unreasonably high concentration in the colorimetric method. The conventional distillation-colorimetric method (11,17) requires up to 500 mL of water and also requires much apparatus, space, and reagents. Furthermore it is difficult to distill a t the same distillation rate and maintain it. Our proposed HPLC method requires only 1 mL of sample and
a filtration procedure and is accurate and rapid. Registry No. NH4+,14798-03-9;fluorescarnine, 38183-12-9; water, 7732-18-5.
LITERATURE CITED (1) Hikuma, Motohlko; Kubo, Tatsuru; Yasuda, Takeo; Karube, Isao; Suzuki, Shuichi Anal. Chem. 1980, 5 2 , 1020-1024. (2) Meyerhoff, Mark E. Anal. Chem. 1980, 5 2 , 1532-1534. (3) Karube, Isao; Okada, Tadashi; Suzuki, Shuichi Anal. Chem. 1981, 5 3 , 1852-1854. (4) Fraticeill, Y. M.; Meyerhoff, M. E. Anal. Chem. 1983, 5 5 , 359-364.
(5) Grleve, Steven; Syty, Augusta Anal. Chem. 1981, 53, 1711-1712. (6) Anlgbogu, Vlncent C.; Dletz, Mark L.; Syty, Augusta Anal. Chem. 1983, 5 5 , 535-539. (7) Small, Hamish; Stevens, Timothy S.; Bauman, Wllliam C. Anal. Chem. 1975, 47, 1801-1809. (8) Bouyoucos, Spiros A. Anal. Chem. 1977, 49, 401-403. (9) Fritz, James S.; Gjerde, Douglas T.; Becker, Rose M. Anal. Chem. 1080, 5 5 , 1519-1522. 10) Mlzobuchi, M.; Ohmae, H.; Umoto, F.; Tanaka, T.; Ichimura, K.; Ueda, E.; Itano, T. Clln. Chem. (Winston-Salem, N . C . )1983, 2 9 , 408-409. 11) "Standard Methods for the Examlnation of Water and Wastewater", 14th ed.;American Public Health Association: Washington, DC, 1975; pp 406-418. 12) Stein, S.; Boehlen, P.; Stone, J.; Dairman, W.; Udenfriend, S. Arch. Blochem. Slophys. 1073, 155, 203-212. 13) Felix, Arthur M.; Terkelsen, Gene Arch. Blochem. Siophys. 1973, 157, 177-182. (14) Stewart, James T.; Wliliamson, Jonathan L. Anal. Chem. 1978, 48, 1 182-1 185. (15) Sigel, Carl W.; Woolley, Joseph L., Jr.; Nichol, Charles A. J. fharm. Sci. 1975, 64, 973-976. (16) Udenfriend, Sidney; Steln, Stanley; Boehlen, Peter; Dairman, Wallace; Lelmgruber, Wllly; Weigeie, Manfred Sclence 1972, 178, 87 1-872. (17) "Testing Methods for Industrlai Wastewater, JIS K0102, 1981"; Japanese Standards Assoclatlon: Tokyo, 1981; pp 126-127. (18) Kanno, Saburo; Fukui, Syozo; Naito, Syojl; Kaneko, Mlkihiro Eisei Kagaku 1988, 14, 280-284.
RECEIVED for review June 22, 1983. Accepted December 1, 1983.
Determination of Strontium-90 in Urine by Extraction without Ashing Vladimir SEasniir'
Institute of Experimental Pharmacology, Slovak Academy of Sciences, 842 16 Bratislava, Czechoslovakia The elements Na, Ca, Co, Zn, Sr, Cs, Y, Zr, Ru, Ce, and Pm, if ingested or inhaled, will be retained in the body for an appreciable length of time concentrating in the bone and the liver. From the radiotoxicity point of view the radionuclide strontium-90 is the most dangerous component. A survey of the literature shows that most laboratories carry out gross /3 urine analysis. This method detects the presence of radioactive fission products that do not emit y-rays. Better estimates of the retention and the subsequent doses in an actual contamination case can be made if an analysis method to measure strontium-90 specifically in urine is available. However the determination of strontium-90 is usually laborius and time-consuming. Therefore a simple and selective extraction method has been developed for this purpose. The most tedious operation in radiostrontium determination is concentrating it from urine and separating the radionuclide from the mixture of other radionuclides. The methods of precipitation (I-4), ion exchange (5-79, and extraction (8-11) are frequently used for this purpose. Extraction procedures are especially advantageous due to their speed and high selectivity. V i s i t i n g scientist. Present address: U n i v e r s i t y of Montreal, Nuclear Physics Laboratory, Montreal, Quebec, Canada H3C 357.
It was shown (12-14) that dicarbolides of transitions metals possess high selectivity toward cesium, whereas the extraction of strontium is not significant. Dicarbolides of cobalt were used for separation of cesium from the mineralizates of biological tissues (15-1 7), contaminated excreta (18),and milk (19). This paper demonstrates that PEG strongly increases the extraction of microamounts of strontium into nitrobenzene, when the univalent hydrophobic anion of dicarbolide-H+ was used. The mechanism of the synergistic effect of PEG in the extraction of strontium cation is explained by Rais (20). The magnitude of the synergistic effect >lo3 creates good conditions for the extraction of strontium after previous extraction of cesium. Since both radionuclides are most significant components of fission mixture and the extraction of other fission and activated radionuclides using dicarbolide-H+appears to be low, the conditions for a selective and quantitative separation of radiostrontium from contaminated urine were investigated in this work. Dicarbolide-H+ with high stability constant of its complex anion, fully dissociated and stable also in a high acidic media, together with PEG of mean relative molecular mass 300 was used for this purpose. Urine is a complex matrix. Any analytical separation that attempts to isolate an almost insignificant mass of material
0003-2700/84/0356-0605$01.50/00 1984 American Chemlcal Socletv
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ANALYTICAL CHEMISTRY, VOL. 56, NO. 3, MARCH 1984
from urine must be capable of overcoming the high variability of sample composition. The urine is usually ashed to destroy all organic constituents to reduce the complexity of the sample. This step is time- and labor-consuming. In the method proposed no ashing of urine sample is necessary. Accordingly, radiostrontium can be directly extracted from urine after cesium has been extracted, when a proper amount of PEG 300 is added.
EXPERIMENTAL SECTION Reagents and Apparatus. The following radionuclideswere chloride, 22Nachloride, 147Pm used (goSr-goY) nitrate, oxalate, all from Rotop (GDR);(loBRu-losRh) chloride, (NZr-NhTb) nitrate, lSCs chloride, W e chloride, all from Izotop (USSR);"Ca chloride, @Cochloride and @Znchloride from Metronex (Poland). All the radionuclides were carrier-free or with negligible amount of carrier. The amount of radiochemical impurities was below 1%. Radionuclides and were prepared from the wSr-wY mixture by extraction of %r into nitrobenzene (Lachema,CSSR) using mol/L dicarbolide-H+,0.1% (v/v) PEG 300 (Lachema, was CSSR), and 0.1 mol/L nitric acid in an aqueous layer. purified by double scrubbingwith 0.1 mol/L nitric acid containing 0.1% PEG 300. Equal volumes of organic and aqueous layer were used. remains quantitatively in an aqueous layer, also after double extraction of @'Sr. The extraction agent dicarbolide-Cs+ (supplied by Institute of Nuclear Research, Rei near Prague) was in the form of orange powder practically insoluble in water. Dicarbolide-H+was prepared from its cesium salt being dissolved in nitrobenzene by shaking twice for 30 min with an equal volume of 1 mol/L nitric acid. The other concentrations of extractant were prepared by dilution with nitrobenzene. Various concentrations of PEG 300 solutions were prepared mol/L) of PEG 300 by dilution of 1% stock solutions (2.2 X with 0.1 mol/L nitric acid, as well as by further dilution of 1% PEG in nondiluted urine and urine diluted by nitric acid solution, and by urine and distilled water, in volume ratio 1:4,1:9, and 1:19. Radioactive Counting. Strontium-90 in 1mL of both layers was counted in a well type scintillation crystal NaI(T1) connected to NZQ 717 laboratory measuring set (Tesla, CSSR) after (1 month) attainment of radioactive equilibrium (The activity of daughter was counted. The other y emitters were counted in this way as well) and in a liquid scintillation cocktail with spectrometer Tri-Carb Mod. 3390 (Packard, USA), immediately after the extraction and back-extraction of strontium-90 into aqueous layer was finished. (Strontium-90 was back-extracted from nitrobenzene into the equal volume of 0.1 mol/L nitric acid containing 10" mol/L barium nitrate. 1mL of an aqueous layer was added to 15 mL of precooled Bray scintillation cocktail and was counted for radioactivity. Calcium-45and the /3 emitter Promethium-147 were also counted in this way.) Distribution ratio of each radionuclide was calculated as cpm of an organic layer
D = cpm of an aqueous layer
(1)
In the case of the mixture of y emitters the semiconductor Ge(Li) detector of volume 74 cm3with resolution 2.3 keV/channel was used for scanning. The y spectra obtained were analyzed by a microcomputer operated system ND 4420 (Nuclear Data, USA) providing the area calculations under the individual peaks. Sample Preparation for Extraction. Human urine collected from several individuals was used. The urine sample (approximately 100 mL) is diluted with 0.1 mol/L nitric acid to give the final volume 500 mL. No dry or wet ashing of urine is necessary. Extraction Procedure, Figure 1. (1) To 100 mL of diluted urine an equal volume of mol/L dicarbolide-H+ in nitrobenzene and the carrier (CsCl, less than lo4 mol/L) are added. The mixture is shaken for 5 min and the aqueous layer is retained. This step is repeated once more and the combined organic layers are analyzed for 13"Cs. (2) After double 137Csextraction is finished the PEG 300 (final concentration in urine has to be 0.25%) is added to extract %r at the phase ratio org/aq = 1 / 2 by shaking for 5 min with
Table I. Changes of 90SrDistribution Ratio with Nitric Acid Concentration in Aqueous Solutionsa
350.0
10-3 10-2
0.001
0.085
10-l a
0.008
0.5 1.0
8.95
Extraction with
mol/L dicarbolide-Hi.
Table 11. Changes of Radiostrontium and Radioyttrium Distribution Ratio with PEG Concentration in 1 O - I mol/L Nitric Acid PEG,
vlv % 1.0 0.1 10-2
10-3 10-4 10-5 0 a
LSSM D 90Sr
NaI(T1) D 85Sr
NaI(T1)
216 603 250 29.1 2.7 0.3
264 628 251 24.9 2.6 0.3
0.063 0.092a 0.009
0.1
0.1
0.003
D
0.011
0.007 0.004
PEG 0.25%.
Table 111. Extraction of E5Srfrom Urine, Changes of 85SrDistribution Ratio with PEG and Dicarbolide-Ht Concentration D 85Sr
PEG, v/v %
5.0 2.5 1.0 0.5
0.25 lo-' 10-2 10-4 0
mol/L DC-H+ 0.08 0.16 0.24 0.30
0.41 0.25 0.14 0.04 0.01
10-1mol/L DC-H+
8.6 12.5 40.5 35.6 30.4 14.9 8.6 5.4 0.6
mol/L dicarbolide-H+in nitrobenzene without addition of carrier. This is repeated once more. (3) Two nitrobenzene extracts are combined (100 mL) and an equal volume of 0.5 mol/L nitric acid containing 0.5% PEG 300 is added for scrubbing of radioactive impurities. The aqueous layer is discarded. mol/L (4) Strontium-90 is back-extracted into 5 mL of barium nitrate in 0.1 mol/L nitric acid. The organic layer is discarded. (5) To 5 mL of an aqueous layer 15 mL of precooled Bray scintillation cocktail is added for counting, using liquid scintillation technique.
RESULTS AND DISCUSSION Under conditions suitable for extraction of 13'Cs (D= lbr for mol/L dicarbolide-H+ and 0.1 mol/L nitric acid), the is very low, as can be seen from Table I. The extraction of extraction of strongly increases with decreasing nitric acid concentration, and the distribution ratio D reaches a magnitude of 350 in low3mol/L nitric acid. Similar results were found also for most of the other radionuclides. However, it was found that hydrophobization of ion associates with the PEG supports the passage of strontium into an organic layer (22). The changes of distribution ratio of %3r, and 85Sr with the concentration of PEG in aqueous solution at lo-' mol/L dicarbolide-H+ showed that with increasing concentration of PEG the distribution ratio increased by about 3 orders of magnitude and reached the maximum value in 0.25% PEG as seen from Table 11. The distribution ratio of yttrium
ANALYTICAL CHEMISTRY, VOL. 56, NO. 3, MARCH 1984
607
Table IV. Effect of Urine Dilution and Nitric Acid Concentration on the Value of "SI Distribution Ratioa D 85Srin nitric acid at the following mol/L dilution urine:water 0.0 10-2 10-I 0.5 1.0 1:o 1:4 1:9 1:19 0: 1 a
Extraction with
0.28 5.25 24.4 27.2 3 50
0.4 9.15 41.8 45.6 628
0.5 10.6 47.9 55.7 715
0.86 11.6 38.8 82.7 1302
0.23 2.14 5.21 9.56 22.3
mol/L dicarbolide-H+in nitrobenzene at 0.25% PEG in aqueous layer.
Table V. Values of Distribution Ratios of Some Fission and Activated Radionuclides at Proper Conditions for Radiostrontium Extraction distribution ratio of radionuclides urine:water 1:4 distilled water urine:water 1 : 4 urine:water 1:4 mol/L md/L mol/L 10-I mol/L BC-H+,10.' DC-H', 0.5 DC-H+,0.5 DC-H', 1 0 - 1 mol/L HNO,, mol/L HNO,, mol/L HNO,, mol/L HNO,, 0.25% PEG 0.25% PEG radionuclide 1%PEG 0.25% PEG 22Na
95Zr Io6Ru
0.47 0.98 0.93 0.91 389 12.15 0.025 0.030
l37CS
101
Ta
oco 6 5zn
85Sr 90Y
144Ce l 4 'Pm
40.18 0.039
0.008 0.005 0.001 0.001 5.25 0.005 0.001 0.001 0.72 0,001
0.022 0.010 0.012 0.014 9.15 0.041 0.005 0.002 3.64 0.058 0.002
reached the maximum at the same concentration of PEG, but its value was much lower. No significant differences between distribution ratios of 93r and %Sr were found. Results in Table I11 give evidence that the maximum value of the distribution ratio has been reached at different PEG concentrations depending on dicarbolide-H+ concentration used in the experiments. The highest distribution ratio with mol/L dicarbolide-H+ in nitrobenzene was reached at 0.25% PEG concentration in urine. When 16' mol/L dicarbolide-H+ was used, the maximum of the distribution ratio occurs at 1% PEG concentration in urine and its value is about 100 times higher than before. Results in Table I11 also show that the distribution ratio of radiostrontium extracted from urine using mol/L dicarbolide-H+in nitrobenzene is about 3 orders of magnitude lower than that from an aqueous layer. The maximum value of the distribution ratio in both cases occurs at 0.25% PEG concentration. Both dilution of urine and nitric acid concentration have shown a significant influence on radiostrontium extraction. Effect of these factors on the distribution ratio of 85Sris given in Table IV. A rapid increase of the distribution ratio of 88Srwith the dilution of urine and with decreasing nitric acid concentration using mol/L concentration of extractant is noted. Similar dependence was observed when 10-1 mol/L dicarbolide-H+ and 1% PEG concentrations were used. It is clear that the higher the urine dilution the lower is the detection limit of radiostrontium. On the other hand, the lower the nitric acid concentration in urine the lower is the extraction selectivity of radiostrontium isolated. Accordingly, the corresponding extraction conditions, as are shown in Table IV, for extraction using mol/L dicarbolide-H+and 0.25% PEG are in the range from 0.1 to 0.5 mol/L nitric acid for the urine diluted 5 times. For extraction of radiostrontium from nondiluted urine, the proper conditions are 10-1 mol/L dicarbolide-H+,0.1-0.5 mol/L nitric acid, and 1% PEG. Distribution ratios of the other contaminants under these experimental conditions are given in Table V.
0.109 0.512 0.025 0.024 350 0.030 0.015 0.01 5 9.21 0.061 0.011
0.001
I. EXTRACTION (I:I) 1O-*mol.L-' DC-H+ IO-'mol. L-' HNO,
J
2 , EXTRACTION ( I: I I
1 3 7 ~10-2mol.LJ ~ DC-H+
4 EXTRACTIONII:2)
COMBINED EXTRACTS, COUNTING FOR
i
RADlOACTlVl T Y
I
r
1
"SR
DISCARD
I
1
SCRUBBING ( I I )
0 5mol L-I HNO, ,O 5%PEG
c
i
90SR DISCARD BACK-EXTRACTION(1 20) L-'HN03 I
DISCARD
90SR
1
LIQUID SCINTILLATION COUNTING
Figure 1. Extraction procedure for isolation following I3'Cs separatlon from the mixture of radlonuclides in urine.
According to these data it is clear that radiostrontium can be extracted directly from urine, after cesium has been extracted, when a proper amount of PEG is added. The radionuclidic purity of isolated %Sr depends on both the quality and quantity of the other contaminants in the mixture of radionuclides and on the number of extraction and scrubbing processes used during the course of analysis. Scrubbing does
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ANALYTICAL CHEMISTRY, VOL. 56, NO. 3, MARCH 1984
not practically decrease the yield of radiostrontium as seen from Table V. In the experimental procedure stated above (Figure l),an extraction yield of @'Sr greater than 95% can be reached after double extraction. The radionuclidic purity of isolated %'Sr was verified by y spectrometry and was found to be more than 95% after single scrubbing of impurities. The limit of detection of @'Sris estimated to be 3.7 Bq dm-3. The back-extraction of @'Sr into an aqueous layer must be done because of the strong quenching effect of nitrobenzene. Under the experimentalconditions mentioned above the quantitative back-extraction of '%r into mol/L barium nitrate in lo-' mol/L nitric acid occurs. The radiochemical procedure is completed within 40 min. Finally, it can be stated that the subsequent extraction of radiostrontium following extraction of radiocesium from urine contaminated by a mixture of fission products and activated radionuclides is very selective, quick, and high yielding. The extraction-chromatographic procedure using dicarbolide-H+ as stationary phase is under development.
Registry No. H+[(a-(3)-1,2-CzBsHll)zCo-], 60824-44-4; PEG, 25322-68-3; 22Na,13966-32-0; 46Ca,13966-05-7; @'CO, 10198-40-0; q n ,13982-39-3; %r, 13967-73-2; %r, 1009897-2;Boy, 10098-91-6; s5Zr, 13967-71-0;lOeRu, 13967-48-1;13'Cs, 10045-97-3;144Ce, 14762-78-8; l4'Prn, 14380-75-7.
LITERATURE CITED (1) Gedeonov, L. I.;Ivanova, L. M. Radiokhimicheskii analiz objektov vneschnei sredy. Moskovskoe otdelenie obyedinenykh gosudarstvennykh izdatelstv, Moscow, 1972. (2) Biume, W. Report SZS-2, Staatliche Zentraie fur Strahienschutz, Berlin. 1986. (3) Beneb, J.; Herchi, M. Jad. Energ. 1971, 77, 55. (4) Quick Methods for Radiochemical Analysis; Technical Reports Series bo. 95; IAEA: Vienna, 1969. (5) Cechvaia, L.; Petragova, M. Chem. Listy 1978, 70, 1296. (6) Millard, N. E.; El-Atrash, A. M. Egypt. J. Chem. 1975, 76, 173. (7) Barrata, E. J. Anal. Chem. 1974, 57, 37. (8) Rehak, W.; Feddersen, B. Report SZS-2, p. 17; Staatliche Zentrale fur Strahienschutz, Berlin, 1973. (9) Testa, C.; Delle, R.; Site, A. J . Radioanal. Chem. 1978, 3 4 , 121. (10) Barrata, E. J.; Reavey, T. C. J. Agrlc. Food Chem. 1989, 77, 1337. (11) Kyrb, M.; Rais, J.; Seiucky, P.; Kadlecova, L. J. Radioanal. Chem. 1978, 2 9 , 15. (12) Hawthorne, M. F. Pure Appl. Chem. 1972, 2 9 , 547. (13) Rais, J.; Selucky, P.; Kyr& M. J. Inorg. Nucl. Chem. 1978, 38, 1378. (14) SEasnBr, V.;.Koprda, V. Radlochem. Radioanal. Lett. 1978, 3 4 , 23. (15) Koprda, V.; SEasnir, V. J . Radioanal. Chem. 1979, 57, 245. (18) SEasnir, V.;-Koprda, V. Radlochem. Radloanal. Lett. 1979, 39, 75. (17) Koprda, V.; SEasnir, V. Chem. Zvestl 1980, 34, 480. (18) SEasnBr, V.;Koprda, V. J . Radioanal. Chem. 1980, 59, 389. (19) Koprda, SEasnir, V. Radiochem. Radioanal. Lett. 1980, 4 4 , 349. (20) Rais, J.; Sebestova, E.; Seiucky, P.; Kyrb, M. J . Inorg. Nucl. Chem. 1978, 38, 1744. (21) Stefek, M.; Kyr5, M.; Rais, J. Zh. Anal. Khim. 1978, 37, 1364.
v.;
RECEIVED for review August 12,1983. Accepted October 11, 1983.
CORRECTION Determination of Carbon Monoxide with Tetrachloropalladate(I1)-Cacotheline Reagent Jack L. Lambert and Yuan C. Chiang (Anal. Chem. 1983, 55, 1829-1830). It has been brought to our attention that the amount of cacotheline specified to prepare the 4 X M stock solution should be 0.855 g rather than 10.94 g. Also, while 0.443g of palladium(I1)chloride is the correct amount for preparing the 1X M tetrachloropalladate(I1) stock solution, this is 0.002 50 mol, rather than 0.0250 mol, of PdC12.
