Different methods are available for the purification of recovered enriched water from FDG synthesis units. Procedures for organic solvents elimination as: irradiation of the water with UV light, oxidation with KMnO4/NaOH (Rötering et al., 2015), electrolysis (Huang et al., 2003; Weber et al., 2003), ozonolysis (Asti et al., 2007) or He gas purging are proposed. All these methods can remove organic impurities, but they cannot eliminate metallic impurities coming from the [18F]F-targets. Some of the inorganic and metallic impurities can be removed by solid-phase extraction (SPE) methods through ion–ion exchange reactions, IC–Chelate cartridges (Razpotnik et al., 2003), or slow distillation under vacuum (Rötering et al., 2015). All authors report very good results for purification and negligible decreasing of [18F]FDG yields using recycled [18O]H2O but without clear view about generated radioactive waste and radiation safety of involved personal.
A simple, effective, easy-handling and reliable method for recycling of [18O]H2O, used for 18F production, is developed based on co-precipitation, co-crystallization and distillation. Preliminary experiments with normal H2O were used to determine the optimal purification conditions. The obtained recycled [18O]H2O had comparable quality to commercially distributed 18O enriched water. The loss of enriched water was about only 7 % and losses of 18O enrichment about 1.3% ± 0.2%. The method ensures elimination of radioisotopes (99.7% ± 0.1%), organic compounds (99.5% ± 0.1%) and trace metals (99.8% ± 0.1%) with special attention on radiation safety and generated radioactive waste.
Key words: H218O; Purification; Recycling
Astia, M., Grassib, E., Sghedonib, R., De Pietria, G., Fioronib, F., Versaria, A., Borasib, G., Salvoa, D., 2007. Purification by ozonolysis of 18O enriched water after cyclotron irradiation and the utilization of the purified water for the production of [18F]-FDG (2-deoxy-2-[18F]-fluoro-D-glucose). Applied Radiation and Isotopes, 65, 831–835.
Huang, B. X., Channing, M. A., Plascjak, P. S., Kiesewetter, D. O., Der, M., Ma, Y., Eck- elman, W. C., 2003. Routine quality control of recycled target [18O]water by capillary electrophoresis and gas chromatography. Nucl. Med. Biol. 30, 785–790.
Razpotnik, P., Tursic, J., Veber, M., Novic, M., 2003. Efficiency and characteristics of solid-phase (ion-exchange) extraction for removal of Cl- matrix. Issue Series Title: J. Chromatogr. A 999 (1), 23–29.
Rötering, S., Franke, K., Zessin, J., Brust, P., Füchtner, F., Fischer, S., Steinbach, J., 2015. Convenient recycling and reuse of bombarded [18O]H2O for the production and the application of [18F]F-. Applied Radiation and Isotopes, 101, 44–52.
Weber, K., Marx, H., Vierling, J., Wittstadt, U., Eisenhut, M., 2003. Electrolytic purification of [18O] water. J. Labeled. Compd. Radiopharm. 46, 279.