Sources of Carrier F-19 in F-18 Fluoride

Fluorine-18 is used for many PET radiopharmaceuticals. Theoretically F-18 should be carrier free and a good candidate for nanochemistry. However, F-18 has 10 to 1000 times more stable fluorine atoms than radioactive atoms. In order to understand the source of carrier fluoride and other ions associated with F-18 radiosynthesis, anion concentrations of different components of F-18 target systems as well as solvents and chemicals used in radiosynthesis were measured. Results: The enriched water used for production of F-18 had low levels of anions. In general, the sources of anions, particularly of fluoride, were the chemical reagents used for synthesis and trace contaminants in tubing, valves and fittings. A major component of contamination was nitrate from irradiation of dissolved nitrogen gas in the target water.