Synthesis of isomers of F-18-labelled amino acid radiopharmaceutical: Position 2- and 3-L-F-18-alpha-methyltyrosine using a separation and purification system

To diagnose cancers with radiolabelled amino acid using positron emission tomography, we have constructed a separation and purification system for the production of L-F-18-alpha-methyltyrosine (L-(FAmT)-F-18). This system could provide radioprotection and consistent production of L-(FAmT)-F-18. L-(FAmT)-F-18 was synthesized and purified and the efficiency of the system was examined. The radiochemical yield of L-(FAmT)-F-18 was 20.3 +/- 5.1% (n = 5) based on the radioactivity trapped in the reaction vessel. The radiochemical purity was greater than 99.4 +/- 0.3% (n = 5). The radiochemical stability in phosphate-buffered saline and human plasma was examined and little decomposition was observed by HPLC analysis. Our results indicate that the separation and purification system gave simple and quick synthesis of L-(FAmT)-F-18 with a large reduction in radiation exposure and consistent production of L-(FAmT)-F-18.