Practical microscale one‐pot radiosynthesis of 18F‐labeled probes |
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| Authors: | Ren Iwata Claudio Pascali Kazunori Terasaki Yoichi Ishikawa Shozo Furumoto Kazuhiko Yanai |
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| Affiliation: | 1. Cyclotron and Radioisotope Center, Tohoku University, Sendai, Japan;2. S.C. Medicina Nucleare, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy;3. Cyclotron Research Center, Iwate Medical University, Morioka, Japan;4. Graduate School of Medicine, Tohoku University, Sendai, Japan |
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| Abstract: | High specific activity is often a significant requirement for radiopharmaceuticals. To achieve that with fluorine‐18 (18F)‐labeled probes, it is mandatory to start from no‐carrier–added fluoride and to reduce to a minimum the amount of precursor in order to decrease the presence of any pseudocarrier. In the present study, a feasible and efficient method for microscale one‐pot radiosynthesis of 18F‐labeled probes is described. It allows a substantial reduction in precursor, solvent, and reagents, thus reducing also possible side reaction in the case of base‐sensitive precursors. The method is based on the use of a small amount of Kryptofix 2.2.2/potassium [18F]fluoride in MeOH (K.222/K[18F]F‐MeOH) obtained using Oasis MAX and MCX cartridges. Five methods, differing in terms of MeOH evaporation and precursor addition, for the radiosynthesis of [18F]fallypride and [18F]FET in ≤50‐μL scale, were examined and evaluated. The method using the addition of DMSO to the K.222/K[18F]F‐MeOH solution prior to MeOH evaporation is proposed as a versatile procedure for feasible one‐pot 10‐ to 20‐μL scale radiosyntheses. This method was successfully applied also to the radiosynthesis of [18F]FES, [18F]FLT, and [18F]FMISO, with radiochemical yields comparable with those reported in the literature. Purification of a crude product by an analytical HPLC column was also demonstrated. |
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| Keywords: | [18F]fallypride [18F]FET microscale radiosynthesis reactive [18F]fluoride |
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