Automated radiosynthesis and purification of [ 18 F]flumazenil with solid phase extraction.

This paper describes the novel approach for preparation of [18 F]flumazenil ([18 F]FMZ), well known radioligand for assessment of GABAA receptors by PET. The optimized reaction conditions allowed us to implement commercially available SPE cartridges for [18 F]FMZ purification avoiding HPLC. All procedures were performed with TRACERlab FX N Pro synthesizer in 53 min. Developed approach provided [18 F]FMZ with high RCP (> 97%) and low level of chemical impurities (< 5 µg/mL). FMZ was routinely synthesized in 6.4 ± 0.7% RCY at EOS (not decay corrected, n = 8) and the molar radioactivity was > 185 GBq/μmol.