Amalgam exchange separation of radiothallium

Short communications

129

Zusammenfassung-Die Oxydation von Brenztrauben- und Lavulinsiiure, Acetaldehyd, Isobutymldehyd und Acetylaceton durch Vanadium(V) in wf&ieer Liisune bei Bestrahlun~ mit sichtbarem Licht wird beschrieben. B’;enztraub&saure wird vyel schneller oxydiert als L&ulins&rre; beide liefem Essigs&tre. Acetaldehyd wird schneller als Isobutyraldehyd oxydiert; ersterer bildet Ameisenslure, letxterer Ameisensiiure und Aceton. Acetylaceton gibt Essig&ure als Produkt. Die Oxydationen gehen schnell und quantitativ und kiinnen zur Bestimmung dieser Carbonylverbmdungen herangezogen werden. REFERENCES 1. 2. 3. 4. 5. 6. 7. 8. 9.

K. S. Panwar and J. N. Gaur, Naturwissenchaften, 1961,4S, 602. Idem, J. Electroanal. Chem., 1962,3, 348. I&m, Indian J. Chem., 1963, 1,361. Idem, Ind. J. Applied Chem., 1964,21,13. Idem, #id., 1964,27,24. Idem, Anal. Chim. Acta, 1965,33,318. C. Renz, Helv. Chim. Acta, 1921,4,961. J. R. Jones and W. A. Waters, J. Chem. Sot., 1963, 352. H. B. Watson, Modern Theories of Organic Chemistry, 2nd ed., pp. 159-180. Oxford University Press, 1941. 10. J. R. Jones and W. A. Waters, J. Chem. Sot., 1960, 2772.

Talanta. 1967. Vol. 14. pp. 129 to 132.

Pergamon Press Ltd.

Printed in Northern Ireland

Amalgam exchange separation of radiothallium (Received 23 May 1966. Accepted 9 August 1966) AMALGAMexchange is a rapid and selective method which may be used for the separation of various elements. Although this technique was Srst used in 1936 by Lewis and McDonald’ for enriching lithium isotopes, only recently has it been applied to the radiochemical separation of various elements. The method has been used for the radiochemical separation of cadmium,* zinc* and indium.’ Limited studies on the amalgam exchange of strontium and thallium have also been reported.6 The procedure developed in this investigation is rapid and selective and may be used to separate short-lived isotopes such as thallium-202, and determine their activities. EXPERIMENTAL Standard radiochemical equipment was used throughout this work. Beta-activity of thallium-204 was counted with an end-window Geiger tube of the halogen-quenched type which was mounted in a vertical lead shield. Reagents Thallium-204 was obtained from the Isotopes Division of Oak Ridge National Laboratory. The desired activity was obtained by dilution of the tracer with O*lM nitric acid. Ethylenediamine, 85 % solution in water. Mercury, reagent-grade (base metals 1 x lo-‘%, foreign metals 5 x 10--40/o). Nitrogen gas, water-pumped, stored in tank. Thallium metal, 99+ %, Amend Drug and Chemical Co., New York. Thallium amalgam, 3 %; O-88 g of thallium metal was cleaned with O.lM nitric acid and mixed with 2 ml (27.2 g) of mercury in a test-tube. The amalgam was kept under distilled water and oxygen was removed from the system by purging with nitrogen. Preliminary experiments Radiothallium solution was mixed with various reagents, flushed with nitrogen to remove oxygen

130

Short communications

and then shaken with thallium amalgam. Portions of the aqueous phase were than removed and their activity measured to determine the amount of exchange that had occurred. The amalgam phase was then separated and shaken with a back-extractant, and the amount of radiothallium extracted into the aqueous phase was measured by counting its activity. Anions, complexing agents and pH exert definite effects on the eihciency of the exchange steps. Several anions and complexing agents were investigated to obtain maximum efficiency in the amalgamation step. Fluoride, nitrate, sulphate and perchlorate were the anions investigated. Ethylenediamine (EDA), triethanolamine (TEA), phenylethylamine (PEA), EDTA, hyamine perchlorate and ammonia were tried as complexing agents. The results of this investigation are summarixed in Table I. The degree of exchange observed in the presence of PEA, TEA, and EDA is almost identical. Hyamine perchlorate inhibits the exchange step. The ethylenediamine and fluoride systems were selected for extensive study. TABLE I

Anion or complexing agent

B04T1added, cpm

Total activity in aqueous phase CPm

Exchange into the amalgam, %

O*lM Hyamine perchlorate PEA, 25 % TEA, 25 % EDA, 2.5 % O*lM EDTA 0.25M Ammonia 0*25M Fluoride 0*25M Sulphate 0.25M Perchlorate 0.25M Nitrate

22450 22450 22450 22450 22450 22450 8890 8890 8890 8890

20500 1350 1335 1360 2980 3475 336 1323 567 600

8.5 94.0 94.0 93.9

86.7 84.6 96.2 85.1 93.6 93.2

It was found that dilution of the amalgam by the addition of 1 ml of mercury to 100 ,~l of amalgam increases the efficiency considerably. With undiluted amalgam, the back-extraction step had an efficiency of approximately 20 %, but with the diluted amalgam the efficiency rose to 97 %. Various acids were studied in the back-extraction. A summary of this investigation is given in Table II. TABLE II.-EFFECT OF VARIOUSACIDS ON BACK-EXTRACTION

Exchange system

%O’Tl exchanged into amalgam, %

Back-extractant

*OrTl back-extracted into amalgam, %

500,ul tracer + 100,~l EDA + 100 ~13 % amalgam + 500 ,ul 0.1 M NH,OH

91.7 92.2

Co** 2ml Coa+: 2 ml + 1 ml 6M HCl

21.7 16.0

5OOyltracer+2OOylEDA+ 500 ~10.1 M NH,OH + 200 ~13 % amalgam

93.2

Coa+, 2 ml + 2 ml 0.5M HNO, Co*+, 2 ml + 1 ml 1M CH,COOH Co%+, 2ml+ 1 ml 1M HClO,

19.0

92.9 93.5

20.2 13.7

Amalgam diluted with 1 ml of mercury before back-extraction 500 ,~l tracer + 200 ,uI EDA + 500 ~1 O*lM NH,OH + 200,~13%amalgam

92.9 93.2 93.7

Co*+, 2 ml + 1 ml 1M HC104 Co*+, 2 ml + 1 ml 0.5M HNOCo*+, 2ml + 1 ml 1M CH&OOH

88.7

97.0 97.3

131

Short communications

The effect of pH on the amalgamation step was studied and a summary of the results is given in Table III. It is observed that the exchange is not greatly affected by the change in pH except when nitric acid is present. In this case, it is possible that the thallium in the amalgam is oxidized by the nitric acid and extracted, and so the efficiency of isotopic exchange is lowered. A pH above 3 is preferred. TABLE III.-Emm

OF pH Exchallge into

PH

System

begs,

%

200 ~1 tracer + 100 ~13 % amalgam lml4MHN0, + 3mllMNaF lml0~4MHNO,+3mllMNaF 3 ml 1MNaF + 1 ml HI0 + 3 ml 1M NaF + 1 ml HI0 + 3 ml 1M NaF -I- 1 ml HI0 + 3 ml 1M NaF -I- 1 ml Hz0 +

0.lMNH,OH O*lM NH,OH 0.134 NH,OH 1 ml 0.5M NH,OH

0 1 3 4 7 11.2

88.7 93.6 96.7 96.3 97.6 96.4

TABLE IV.-EFFICIENCY OF PROCEDURE

Complex@

agent

EDA, 0.21% Fluoride, 0*25M

Amount exchanged into amalgam, %

Amount extracted from diluted amalgam, %

93.5 f 1.4 94.3 zt 1.4

960 f 1.1 94.8 * 0.5

Overall recovery, % 896 f l-6+ 89.3 f l.lt

Errors quoted are standard deviations * Average of 8 experiments t Average of 9 experiments Ama&m exchange procedure for thallium-204 On the basis of the preceding studies, the following procedure was devised for the amalgam exchange separation of thallium-204. Amalgam exchange step: 500 ,ul of thallium-204 tracer were mixed with 500 ,ul of 0-W ammonia in a test-tube, and 100 ~1 of 85 % ethylenediamine or 3 ml of 1M sodium fluoride were added. If EDA was added, the solution was diluted to 4.0 ml with distilled water. Nitrogen was passed through the sample to remove oxygen. Then 100 ~1 of freshly prepared 3 % amalgam were added, and the testtube was stoppered tightly and shaken vigorously for 5 min. Then 500 ~1 of the supematant liquid were transferred to a planchette, dried and counted for 5 min. The per cent activity exchanged mto the amalgam was calculated. A standard was also counted under the same conditions. Back-extraction step: the supematant liquid was removed by syringe micro-pipette and the amalgam was washed with 1 ml of distilled water. The amalgam was dried with a Kleenex tissue and the amalgam bead transferred into another test-tube containing 1 ml of mercury, 3 ml of cobalt nitrate solution (50 mg of Co/ml) and 1 ml of 0*5M nitric acid. The diluted amalgam was shaken with the aqueous solution for 4 min. The supematant liquid was transferred into a fresh test-tube and the amalgam was washed with 1 ml of O*lM nitric acid which was then added to the aqueous phase already separated; 500 ~1 of this solution were transferred to a planchette, dried and counted for 5 min. For short-lived isotopes, a shorter mixing time may be chosen. The etIiciencies of extraction from the amalgam and of overall separation were calculated. RESULTS The procedure with ethylenediamine and sodium fluoride as the complexing agents was carried through and the results are given in Table IV.

132

Short convictions

The minhmtm time needed for this procedure is about 7 min and the recoveries are about 90%. This procedure, therefore, satisfies the need for a rapid, efficient and simple radiochemical separation for thallinm isotopes. Chemistry Department Wayne State Un~rsi~ Detroit Mich@an 48202, U.S.A. ~ep~t~~t of Chemistry Scltool of Pharmacy TernpIe University Philadelphia, Pennsylvania, U.S.A.

FUCHARDB. HAHN GEORGE M. KANAPILLY

Sunuaa~-A method is presented for the rapid separation of radiothallium, The solution is made basic by addition of ammonia, then sodium fluoride and ethylenediamine are added and the mixture is shaken with 3 y0 thallium’amatgao;l. A rapid exchange takes place and the bulk of the activitv is concentrated in the amalgam. The amalgam is diluted with clean’mercury and shaken with &die cobalt n&ate solution which back-extracts thallium. About 90% of the thallium activity is recovered. R&nn&-On presente une methode pour la separation rapide du ~dio~li~. La solution est aicaliisee par addition ~~o~aque, nuis on ajoute du fluorure de sodium et de l’ethylenediamine et a&e le m&ange ‘;tvec de I’amalgame de thallium B 3%. I1 se prod& un &hanse raoide et la maieure uartie de l’activite est concentr6e dam l’ama&&. On dilue l&nal&me au moyen de mercure propre et l’agite avec une solution acide de nitrate de cobalt qui r&xtrait le thallium. On r&up&re environ 90 % de l’activiti: du thallium. Zu~~a~~-~rn Verfahren zur schnellen Abtrenmmg von Radiothallium wird angegeben. Die Losung wird durch Ammoniakzusatz basisch gemacht, Na~iu~uorid und ~thyIen~~in zugesetzt und mit 3 o/di&m Thalliumamalgam geschtlttelt. -Es findet ein r&.cher Austausch statt, naeh dem der Hauptteil der Aktivitat sich im Amalgam befindet. Das Amalgam wird mit reinem Quecksilber verdwt und mit sauberer Kobaltnitratlosung geschtittelt, die das Thallium wieder extrahiert. Etwa 90 % der Thulium-Aktivit~t werden wiedergewonnen. REFERENCES 1. G. N. Lewis and R. T. McDonald, J. Am. Gem. Sot., 1936,58,2519. 2. J. R. DeVoe. W. W. Meinke and H. W. Nass. Anal. Chem., 1961,33,1713. 3. W. B. Silker; ibid., 1961,33,233. 4. J. R. DeVoe, W. W. Meinke and R, R. Ruck, Xalanta, 1962,9,33. 5. R, S. Mddock and W. W. Meinke, Progress Repurt (II), U.S.A.E.C. Project No. 7, contract No. ATC-1 l-l-l 143, Dept. of Chem., Univ. of Michigan, AM Arbor, Michigan, Nov., 1962. 6. S. Froneur and C. A. Ostman, Acta. Chem. Stand., 1954,8,961. 7. C. N. Reilley and W. G. Schibner, Ana!. Cbem., 1958,X$1452. 8. W. B. Schaap, Advances in the Chemistry of the Coordination Compounds, Macmillan, New York, 1961. 9. V. P. Vasilev and Y. 3. Yatsimirski, &stability Constants of Complex Compounds, Consultants Bureau, New York, 1960.