A method to obtain a radiofluorinated compound of Formula I: wherein: R 1 is hydrogen, halo or C 1-3 alkoxy; R 2 and R 3 are independently methyl, ethyl or benzyl, or together with the nitrogen to which they are attached form a pyrrolidinyl, piperidinyl, azepanyl, or morpholinyl ring; Y 1 is CH 2, CH 2 -CH 2, CH(CH 3)-CH 2, or CH 2 -CH 2 -CH 2; and; n is 1, 2 or 3. wherein said method comprises: (i) providing a precursor compound of Formula Ia: wherein R 1a-3a, Y 1a and m are as defined for and are each the same as R 1-3, Y 1 and n of Formula I, respectively, and LG is a sulfonate leaving group; (ii) reacting said precursor compound of Formula Ia with a suitable source of [ 18 F]-fluoride; (iii) purifying the reaction mixture obtained in step (ii), wherein said purifying step comprises: (a) providing one or more solid-phase extraction cartridges wherein the sorbent comprises particles having a diameter between 10-120μm and bonded hydrocarbons; (b) conditioning said one or more SPE cartridges; (c) loading the reaction mixture onto said one or more conditioned SPE cartridges; (d) washing said one or more SPE cartridges onto which said mixture is loaded using a first solvent system comprising a ratio of water:water-miscible organic solvent in the range 100:0-0:100; and, (e) eluting said one or more SPE cartridges following said washing step using a second solvent system comprising a ratio of water:water-miscible organic solvent in the range 70:30-0:100 with the proviso that in said purifying step HPLC is specifically excluded. R 1 is hydrogen, halo or C 1-3 alkoxy; R 2 and R 3 are independently methyl, ethyl or benzyl, or together with the nitrogen to which they are attached form a pyrrolidinyl, piperidinyl, azepanyl, or morpholinyl ring; Y 1 is CH 2, CH 2 -CH 2, CH(CH 3)-CH 2, or CH 2 -CH 2 -CH 2; and; n is 1, 2 or 3. (i) providing a precursor compound of Formula Ia: wherein R 1a-3a, Y 1a and m are as defined for and are each the same as R 1-3, Y 1 and n of Formula I, respectively, and LG is a sulfonate leaving group; (ii) reacting said precursor compound of Formula Ia with a suitable source of [ 18 F]-fluoride; (iii) purifying the reaction mixture obtained in step (ii), wherein said purifying step comprises: (a) providing one or more solid-phase extraction cartridges wherein the sorbent comprises particles having a diameter between 10-120μm and bonded hydrocarbons; (b) conditioning said one or more SPE cartridges; (c) loading the reaction mixture onto said one or more conditioned SPE cartridges; (d) washing said one or more SPE cartridges onto which said mixture is loaded using a first solvent system comprising a ratio of water:water-miscible organic solvent in the range 100:0-0:100; and, (e) eluting said one or more SPE cartridges following said washing step using a second solvent system comprising a ratio of water:water-miscible organic solvent in the range 70:30-0:100 (a) providing one or more solid-phase extraction cartridges wherein the sorbent comprises particles having a diameter between 10-120μm and bonded hydrocarbons; (b) conditioning said one or more SPE cartridges; (c) loading the reaction mixture onto said one or more conditioned SPE cartridges; (d) washing said one or more SPE cartridges onto which said mixture is loaded using a first solvent system comprising a ratio of water:water-miscible organic solvent in the range 100:0-0:100; and, (e) eluting said one or more SPE cartridges following said washing step using a second solvent system comprising a ratio of water:water-miscible organic solvent in the range 70:30-0:100