Advances in processes for PET radiotracer synthesis: Separation of [18F]fluoride from enriched [18O]water

• New developments in processing of [18F]fluoride from [18O]water are detailed.
• Efficient separation is required for dose-on-demand radiopharmaceuticals.
• Electrode trapping of [18F]fluoride offers significant advantages for solvent exchange.
• Microfluidic devices complement novel technologies for isotope separation and synthesis.

Positron emission tomography (PET) is a powerful scientific and clinical tool for the study and visualization of human physiology that can provide important information about metabolism and diseases such as cancer. At present, [18F]fluorodeoxyglucose ([18F]FDG) is the most frequently used radiotracer for the routine clinical evaluation of malignant tumors in a range of body tissues. FDG synthesis is continuously being developed to improve and simplify the synthetic procedure including the isolation of [18F]fluoride from [18O]water. There are many methods reported in literature for the isolation of [18F]fluoride, including evaporation, coat-capture–elution, the use of cation-exchange resin and electrode trapping. This review article gives an overview of some of the most common methods for the separation of [18F]fluoride ions from [18O]water, highlighting the potential strength of the methods and also problems and weaknesses for synthesis of 18F PET tracers.