The present invention provides a simplified method for the preparation of 18F-labelled compounds that is particularly suitable for automation. The method of the invention is specifically applicable where the 18F-labelled compound is prepared from a labelling precursor that comprises protecting groups and wherein the synthetic route to the final compound includes removal of these protecting groups by acid or alkaline hydrolysis. Also provided by the present invention is a cassette useful for carrying out the method of the invention in an automated manner.