A method of conducting radiofluorination of a substrate, includes: (a) contacting an aqueous solution of [18F] fluoride with a polymer supported phosphazene base for sufficient time for trapping of [18F] fluoride on the polymer supported phosphazene base； and (b) contacting a solution of the substrate with the polymer supported phosphazene base having [18F] fluoride trapped thereon obtained in step (a) for sufficient time for a radiofluorination reaction to take place.
