Enrichissement isotopique de C14 par chromatographie en couche mince

60

Technical notes

low concentration. Its utility has been further demonstrated in the presence of excess additives. The greater simplicity and speed of this technique over conventional vacuum and mass spectrometric techniques suggests a wider use for this technique in the future.

tillon. Neammoins cette purett fut demontree pal analyse selon la methode de MAROS@). Ainsi le pit ra. dioactif ne pouvait etre dti qu’au formiate de sodium Le formiate de sodium Cl4 avait migre a unc vitesse plus grande que le formiate de sodium Cl: lors de la chromatographie en couche mince. D’autre: experiences furent conduites avec du formiate dr sodium Cl4 d’activitt sptcifique decroissante dans 1~ solvant : alcool: eau : ammoniaque. Les taches furenl dttectees a l’aide de vert de bromocrbol en m&me temps que l’activitt Ctait enregistrte. Les resultatr sont rapport& au Tableau 1. Au fur et a mesure que l’activitt sptcifique decroit, le pit radioactif se rapproche de la tache de la substance inactive. On voit que pour des activites specifiques superieures a 0,02 mCi/mM on peut rtaliser un enrichissement isotopique. Cette methode est done prometteuse pour l’obtention de fortes activitts en Cr4. Les rtsultats ulterieurs seront publits ailleurs.

D. A. JEFFREY J. F. KIRCHER

Chemical Physics Division Battelle Memorial Institute Columbus 1, Ohio, U.S.A. Reference

1. KATAYAMA M., WHITMER J. C. and TRUMBORE C. N. J. Amer. them. Sot. 84, 4025 (1962).

IntenmtionalJournal PP. 60-61. Pergamon

ofApplied Radiation Press Ltd. Prmted

and Isotopes, 1965 in Northern Ire&$

Couche

Vol. 16.

Mince Partie

29 May Introduction A LA SUITE de la publication recente sur la separation des isotopes du carbone par Cchange d’ions par DAVIDSON et al.(l) nous souhaitons publier nos propres r<ats dans ce domaine. Au tours d’experiences de caracttrisation de formiate de sodium Cl4 de forte activitt specifique (16 mCi/mM) par chromatographie sur papier, nous avons observe que la tache radioactive se trouvait toujours a un Rf plus tleve que la tache inactive revtlte par le vert de bromocresol. Comme les taches ttaient toujours quelque peu diffuses, l’interprttation du phenomene En consequence l’experience fut ttait difficile. rep&e, utilisant la chromatographie en couche Nous avons alors trouvt une difference mince. notable entre les Rf de la substance active et inactive. Ce qui nous a ament a douter de la purett de l’tchan-

experimentale

On a utilise du “Kieselgel G”. Solvant: alcool (99%) :eau, ammoniaque (d = 0,925) = 146: 14:32 (vol/vol) . Les chromatogrammes Ctaient developpts pendant 1 hr 40 min. Le front du solvant migrait de 12 cm. Apres stchage a 100% pendant 3 min et refroidissement, les chromatogrammes Ctaient rev&s a l’aide de vert de bromocrtsol. Les taches correspondant au formiate Cl2 apparaissaient en jaune sur un fond bleuvert pale. Dans les 5 experiences du Tableau 1 aucune tiche visible n’etait apparente a l’endroit de la tache radioactive. Les taches radioactives Ctaient enregistrees a l’aide d’un compteur G.M. Remerciements-L’auteur remercie le Gouvernement FranGais (ASTEF) pour l’octroi d’une bourse dans le cadre de la cooperation technique ainsi que le CEN Saclay et MM. PICHAT et HERBERT pour

TABLEAU 1

Experience 1 2 3 4 5 6

Act. sptcifique (mCi/mM) 16 1 022 0,1 0,02 0,Ol

Quantite appliqute Concentration l/16 M 1,0 M I,0 M 1,0 M 1,0 M 1,0 M

(Id) 2 2 2 3 4 4

Valeurs actif 0,810 0,777 0,715 0,703 0,674 0,646

des Rf inactif 0,646 0,654 0,63 0,63 0,63 I

61

Technical notes d’utiles travail.

discussions

et l’interet

qu’ils

ont port6

a ce

K. V. VISWANATHAN* Section des .\foltkuies Marqukes CEN Saclay Gif-sur- I’wtie (Seine ef Oise) France References 1. DAVIDSON C. N., MAR C. K. J. phys. Chem. 67, 1519 (1963). 2. MAROS L. et PINTER~ZAKACS 25, 546 (1961).

et SHELIN Analyt.

R.

K.

chim. acta

* Permanent address: Labelled Compounds Section, Radiochemistry and Isotopes Division, Atomic Energy Establishment Trombay, Bombay 73, India.

M NaCl FIG.

2. Effect

and concentration, colloid (gelatin). International JournalofApplied Radiationand Isotopes,1965, Vol. 16, pp. 6143. Pergamon Press Ltd. Printed in Northern Ireland

The

Radioiodide

Sequestering

of the Silver

Action

Halides

(Received 29 April 1964) PREVIOUSLY the author indicated the use of silver iodide and silver chloride as a sequestering agent for radioiodide in solution, in the case of contaminated drinking water and for the purification ofradioiodine compounds.t1r2) This work was performed to study the behavior of both silver halides as radioiodide sequestering agents under different conditions of temperature, pH,

0

’

1

to-*

I

10.’

I

10-7we

I

I

to-’

to-4

Carrier free,

FIN. 1. Effect

of different

I

I

!

lo-” 10-L to-’

M KI

iodide concentrations.

I

of different of iodide,

NaCl NaCl

concentrations. or an

organic

Experimental The sequestering material was prepared by impregnation of kieselguhr (or other porous materials such as Hyflo Supercel, Celite, etc.) with a 10 per cent solution of Ag NO,. The excess of this solution was eliminated by gentle suction, and the impregnated material was then immersed in a 10 percent solution of NaCl or NaI, to form AgCl or AgI in the inert matrix. Subsequently it was washed with distilled water, until the washing water gave a negative reaction with AgNOs. Finally the material was dried by heating (max temp. 80°C). The carrier-free NaI131 solution used, was brought to pH 1.0 with HCl and after a few minutes, to neutrality (pH 7.0) with NaOH and then tested for iodate by electrophoresis, using KUNKEL’S method(3). Under these conditions iodate was not found. For 10 min 20 ml of this carrier-free solution of NaI131 (approx. 0.1 m/c) was stirred with 50 mg of the silver halide preparation using a magnetic stirrer. The experimental conditions with regard to temperature, pH and salt concentration were as shown in Figs. l-5. After stirring, the liquid was centrifuged for 5 min at 2500 rev/min. A sample of the supernatant was taken and the radioactivity counted. Triplicate assays were made, all glassware being washed before and after with a 5 percent solution of NaI and enough water to prevent adsorption of activity on the glass. It was intended originally to separate the suspended material by filtration, but this was found to be impractical due to the adsorption of activity on the filter paper (Figs. 6 and 7). To minimize absorption, plastic centrifuge tubes were used, previously treated with NaI solution as described above.