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- Author or Editor: I. Galaţeanu x
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Abstract
The radiation stability of methionine-35S and selenomethionine75Se was investigated using the methods of thin-layer chromatography, gas chromatography and ESR. Radiation decomposition of methionine-35S mainly consists in an oxidation process and in the release of volatile products. The ESR-spectra of irradiated DL-methionine indicated a strong localization of the unpaired electrons on sulfur atoms. Radiation damage to selenomethionine-75Se as a function of radiation dose proved an increased stability of this compound, and its radiation decomposition consists in the formation of oxidized products and by direct rupture of the selenium bonds accompanied by the formation of volatile compounds like CH3SeH and SeH2. The self-radiolysis of the aqueous solution of selenomethionine-75Se during its storage in air leads, however, to a lower decomposition rate which consists in the release of inorganic selenium and in an oxidation process.
Abstract
The lower valence states of technetium under the conditions of the preparation of radiopharmaceuticals were studied by polarography and cerimetry. The results indicate that the reduction of Tc(VII) by ascorbic acid in the absence of HCl takes place only to Tc(V), but in the presence of 20% HCl to Tc(IV). The reduction of Tc(VII) by stannous chloride proceeds only to Tc(V) and was confirmed by cerimetry. The polarographic reduction of Tc(VII) in the non-aqueous electrolyte acetonitrile, thus firstly studied, indicated a great tendency of technetium reduced species to hydrolyse. The formation of hydrolysed species like TcO(OH)+, TcO(OH)2, for Tc(IV) and TcO(OH) 2 + for Tc(V) is supposed which influence the technetium binding capacity during its incorporation into radiopharmaceuticals.
Abstract
In order to determine the radiochemical impurities in pertechnetate solution as well as that of unbound99mTc in its colloid and complex compounds, in indium chloride solution and related compounds, paper chromatography on Whatman No. 1, thin-layer chromatography on silica gel plates, and paper electrophoresis were applied. A simple method for the determination of radionuclidic purity was developed.
