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The wide use of »C1 (T = 3.1 · 10 6 a) in tracer applications and the demand for high specific activities necessitates special separation techniques. The longlived ^Cl is generally produced via the ^Cl (n, yJ^Clprocess by extended pile irradiation at high neutron flux densities. The obtainable specific activities, however, are limited even in Szilard-Chalmers separations because of the accompanying radiation decomposition. Neutron irradiations of chlorates and Perchlorates have been shown to give rise to high chloride yields [1, 2, 3], but the lack of radiation stability of these compounds imposes a serious limitation to their use in the production of the longlived ^Cl. Similarly, the application of Szilard-Chalmers separations in organic systems does not seem to provide a good tool for the production of Μ 01 in the mCi-range even in favorable cases [4].In our studies on the ligand recoil behaviour in hexahalo-complexes of Re(IV) and Rh(III) [5], we found that the hexachlororhenates and -rhodates show a remarkable radiation stability. Furthermore, the radiochlorine activity appears in only two chemical forms, the labelled parent complex and the carrierfree chloride, e. g. : R 15% 36 C1 (N, Y) 36 CL R K 2 [ReCl e ] • ae Cl" 85% • [itecyci] 2 -In the case of K 3 [RhCl 6 ] an additional alumina column was necessary to separate iridium activity resulting from impurities [5]. The separation procedure and the stability of the complexes were checked with corresponding tracers. For the determination of the ^Cl-activity chloride carrier was added to aliquots of the separated fractions and precipitated as AgCl. The ^Cl-activity of both the chloride fraction and the total chlorine was then measured in a methane flow counter under identical conditions. The radiochemical purity was established by ^-spectroscopy and measurement of the ^-absorption curve. The specific activity of the separated 36 C1 _ -fraction was determined by neutron activation analysis via the short-lived 38 C1. Neutron -irradiated K 2 [ReCl 6 ] dissol. i. 0.1 Ν CHjCOOH Determination of 36 Cl~ -fractionThe six-chlorine-containing complex seemed to be particularly well suited for the preparation of practically carrier-free ^Cl, due to its radiation resistance and simplicity of the product spectrum, despite the relatively low yield of 15% for the chloride fraction. Experimental K 2 [ReCl e ] and K 3 [RhCl e ] (Heraeus GmbH, Hanau)were recrystallized several times from water solution by adding isopropanol. The purity of the material was checked by Differential Thermal Analysis and by chemical analysis. The samples, sealed in quartz ampoules in vacuo, were irradiated in the FRJ-1 at different positions and neutron flux densities (see below, Fig. 3). The irradiation temperature in each case was < 50 °C. The irradiated ampoules were stored for several months to allow the decay of shorterlived activities and then crushed under the surface of O.INCH3COOH for dissolution. The analytical procedure used for the separation of the chloride fraction from the labelled par...

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einem rnit p-Dimethylaminobenzaldehyd anarbbaren Chromogen oxidiert wird. In einem Fall benutzt man verdiinntes Wasserstoffperoxid, im anderen eine gepufferte Chloramin-Ibsung. Wahrend der Ablauf der Peroxidoxidation von Hydroxyprolin gekliirt ist, hat man bisher noch keine Kenntnis uber die Vorgange warend einer Chloraminoxidation.

Zusammenfassung Die 1M . 1M Ir-markierten Folgeprodukte des lel . 1M Ir (n, y) 1M . 1M Ir-Kernproze8ses des in Lösung bestrahlten Na a IrCl,-Komplexes wurden papierelektrophoretisch untersucht und die Zahl, Art und Ausbeute der Rückstoßkomponenten mit denen des kristallinen Systems Na 2 IrCl e · 6 H 2 0 verglichen. Aus dem elektrophoretischen und chemischen Verhalten läßt sich ableiten, daß es sich bei den in der Lösung entstandenen "stabilisierten" Produkten vornehmlich um oktaedrische Aquo-bzw. Aquochloro-Komplexe des Ir-Ill mit kationischem bzw. neutralem Charakter handelt, deren prozentuale Verteilung eine ausgeprägte Abhängigkeit von der Chloridionen-Konzentration der Lösung zeigt. Zum Unterschied von der im kristallinen System ("cage effect") zu 2,2% gefundenen Retention (Ir IV Cl, 2 -+ Ir™ Cl, 8 -) liegen in der Lösung nur weniger als 0,1% des Radioiridiums in Form des Hexachlorokomplexes vor.