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7971936 
Journal Article 
Aspects of 6-[F-18]fluoro-L-DOPA preparation - Deuterochloroform as a substitute solvent for Freon 11 
Fuechtner, F; Zessin, J; Maeding, P; Wuest, F 
2008 
1 
Nuklearmedizin
ISSN: 0029-5566 
47 
1 
62-64 
English 
WOS:000253638400013 
Aim: Replacement of the ecologically harmful solvent Freon 11 (CFCl3) by chloroform for the module-assisted preparation of 6-[F-18]fluoro-L-DOPA based on the electrophilic radiofluorodestannylation of the precursor N-formyl-3,4-di-tert-butoxycorbonyloxy-6-(trimethylstannyl)- L-phenylalanine ethyl ester. Materials, methods: The TRACERlab Fx FDOPA module (GE Medical Systems) was used for the preparation of 6-[F-18]fluoro-L-DOPA. Cyclotron-produced [F-18]F-2 gas (5 GBq) was passed through a cooled solution (5 degrees C) of the stannyl precursor (45 mg) in CDCl3 (10 ml). After the [F-18]fluorination step, HCl (2 ml, 6 mol/l) was added to the solution. Then the reaction mixture was heated at 80 degrees C for 5 min under vacuum to evaporate the chloroform. The hydrolysis to remove the protecting groups was completed by heating the closed reactor at 130 degrees C for 8 min. After cooling to 20 degrees C the reaction mixture was purified by H PLC with two polymer-based RP columns (PRP-1, 7 mu m, 10 x 250 mm, Hamilton) using a solution of AcOH/AcONa (pH 4.7) as eluent. The 6-[F-18]fluoro-L-DOPA fraction was collected and sterile filtrated. Results: Three types of stabilised chloroform were tested for the rodiofluorination of the precursor. Only by use of deutero-chloroform stabilised with silver no significant losses of radioactivity were observed. Thus, 6-[F-18]fluoro-L-DOPA purified by HPLC was obtained in de(ay-corrected radiochemical yields of 25 +/- 3%, ready for human use. Conclusion: CDCl3 has proved to be a convenient solvent for the module-assisted preparation of 6-[F-18]fluoro-L-DOPA. In thiswaythe use of the polluting Freon 11 can be avoided. 
6-[(18)]Fluoro-L-DOPA; electrophilic radiofluorode-stannylation; Freon 11 substitution; deuterochloroform