18F is a positron emitting radionuclide which is produced in cyclotrons by the proton irradiation of isotopically enriched 18O-water. 18F is normally separated from 18O-water using quaternary amine (QMA) functionalized silica and then recovered for use directly as Na18F or labeled to small molecules such as fluorodeoxyglucose (18FDG) for targeted imaging of various diseases by positron emission tomography (PET).