Neither azeotropic drying, nor base nor other additives: a minimalist approach to 18F-labeling

A novel, efficient, time-saving and reliable radiolabeling procedure via nucleophilic substitution with [F-18] fluoride is described. Different radiolabeled aliphatic and aromatic compounds were prepared in high radiochemical yields simply by heating of quaternary anilinium, diaryliodonium and triarylsulfonium [F-18] fluorides in suitable solvents. The latter were obtained via direct elution of F-18(-) from an anion exchange resin with alcoholic solutions of onium precursors. Neither azeotropic evaporation of water, nor a base, nor any other additives like cryptands or crown ethers were necessary. Due to its simplicity this method should be highly suitable for automated radiosyntheses, especially in microfluidic devices.