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99mTc-Methionine complexes from enantiomeric and racemic methionines were prepared controlling reaction parameters such as pH and the concentration of stannous chloride. Some radiochromatographic systems were also examined to determine the labelling yields of 99mTc complexes. The best resolutions of 99mTc complexes were obtained at ITLC-SA developed with acetone and paper chromatography with n-butanol saturated with 0.3N HCI. In the former system, HR-99mTc and 99mTc-methionine complex remained at origin, while 99mTcO4-moved with Rf value of 1. 0. In latter process, HR-99mTc stayed at the origin, while 99mTcO4-and 99mTc-methionine complexes moved with Rf value of 0. 5. By combining of two chromatographic systems, the contents of three 99mTc species were calculated easily. 99mTc Labelling from enantiomeric and racemic methionines had little differences and the optimal condition was found at pH 9.00 and the molar ratio of methionine to stannous chloride od 24:1. The yields of 99mTc complexes from D-, L-, and DL-methionines were 87.6%, 94.1%, and 97.9%, respectively. The results indicated that methionine containing relatively hydrophobic methylthio group (-SCH3) would be labelled with 99mTc by stannous chloride method.
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