Improved Stability and Practicality for Synthesis of 4-Borono-2-[ 18 F]fluoro-l-phenylalanine by Combination of [ 18 O]O 2 Single-Use and [ 18 F]CH 3 COOF Labeling Agents

4-Borono-2-[ F]fluoro-l-phenylalanine ([ F]FBPA) synthesized with [ F]F , produced using the O(p, n) F reaction, has been reported for increasing radioactivity. However, a dedicated system and complex procedure is required to reuse the costly [ O]O gas; also, the use of [ F]F as a labeling agent reduces the labeling rate and radiochemical purity. We developed a stable and practical method for [ F]FBPA synthesis by combining [ F]F , produced using a [ O]O single-use system, and a [ F]CH COOF labeling agent. The produced [ F]F was optimized, and then [ F]FBPA was synthesized. For passivation of the target box, 0.5% F was pre-irradiated in argon. Gaseous products were discarded; the target box was filled with [ O]O gas, and then irradiated (first irradiation). Then, the [ O]O gas was discarded, 0.05-0.08% F in argon was fed into the target box, and it was again irradiated (second irradiation). The [ F]F obtained after this was passed through a CH COONa column, converting it into the [ F]CH COOF labeling agent, which was then used for [ F]FBPA synthesis. The mean amount of as-obtained [ F]F was 55.0 ± 3.3 GBq and that of as-obtained [ F]CH COOF was 21.6 ± 1.4 GBq after the bombardment. The radioactivity and the radiochemical yield based on [ F]F of [ F]FBPA were 4.72 ± 0.34 GBq and 12.2 ± 0.1%, respectively. The radiochemical purity and molar activity were 99.3 ± 0.1% and 231 ± 22 GBq/mmol, respectively. We developed a method for [ F]FBPA production, which is more stable and practical compared with the method using [ O]O gas-recycling and [ F]F labeling agent.