A simple method to generate [18F]triflyl fluoride for 18F radiosynthesis

Abstract

A simple, continuous-flow solid-phase radiosynthesis method has been developed for the generation of [18F]triflyl fluoride as a source of [18F]fluoride for the preparation of 18F labeled radiopharmaceuticals without the need for an azeotropic drying step. After [18F]fluoride was trapped and dried on an anion-exchange resin cartridge, gaseous [18F]triflyl fluoride was generated directly by eluting the cartridge with a solution of PhN(OTf)2, followed by isolation from the eluted reaction mixture via an empty cartridge and conversion to [18F]fluoride in a basic solution for radiofluorination. A peristaltic pump was used to maintain flow through the above stages, eventually providing reaction-ready [18F]fluoride in over 90% radiochemical yield in less than 10 min. Up to 0.057 µg non-radioactive fluoride was introduced from the reagents and components used during the above processes. Several radiolabeling reactions were carried out using the [18F]fluoride generated in this manner, affording the labeled products in good to high radiochemical yields. This method should have great potential for the safe and convenient preparation of 18F labeled radiopharmaceuticals.