A method is provided to purify [F-18]FEONM under a high pressure. The synthesis processes of [F-18]FEONM are integrated. An isolation process of non-toxic radio-high performance liquid chromatography (radio-HPLC) is used to purify the crude product. The method integrates a convention [F-18]FDG synthesizer and a novel radio-HPLC system together in a heat chamber. After radiofluorinating the precursor, the reaction product is purified with an alumina solid-phase column in advance to obtain the crude product while fluorine-18 is removed. Then, diphenyl semipreparative HPLC column is used for a final purification. A non-toxic solvent is used for mobile-phase eluting to remove the unreacted precursor and the phase-transfer solvent. The radiofluorination has a reaction yield about 50 percent (%). The method has an uncorrected radiochemical yield of 10˜20%. Both of the radio-HPLC and the radio-thin layer chromatography (radio-TLC) have radiochemical purity higher than 95%.