Vacuum ultraviolet photon-mediated production of [¹⁸ F]F₂

The chemistry of F₂ and its derivatives are amenable to facile aliphatic or aromatic substitution, as well as electrophilic addition. The main limitation in the use of [¹⁸ F]F₂ for radiopharmaceutical synthesis is the low specific activity achieved by the traditional methods of production. The highest specific activities, 55 GBq/μmol, for [¹⁸ F]F₂ have been achieved so far by using electrical discharge in the post-target production of [¹⁸ F]F₂ gas from [¹⁸ F]CH₃ F. We demonstrate that [¹⁸ F]F₂ is produced by illuminating a gas mixture of neon/F₂ /[¹⁸ F]CH₃ F with vacuum ultraviolet photons generated by an excimer laser. We tested several illumination chambers and production conditions. The effects of the initial amount of [¹⁸ F]F^- , amount of carrier F₂ , and number of 193-nm laser pulses at constant power were evaluated regarding radiochemical yield and specific activity. The specific activity attained for [¹⁸ F]F₂ -derived [¹⁸ F]NFSi was 10.3 ± 0.9 GBq/μmol, and the average radiochemical yield over a wide range of conditions was 6.7% from [¹⁸ F]F^- . The production can be improved by optimization of the synthesis device and procedures. The use of a commercially available excimer laser and the simplicity of the process can make this method relatively easy for adaptation in radiochemistry laboratories.