Production of fluorine-18 by small research reactor

High purity ¹⁸F was prepared by irradiating 1 g of lithium hydroxide or otherwise 0.14 g of enriched lithium carbonate containing 50% ⁶Li in the pneumatic tube of a TRIGA-II research reactor at a thermal neutron flux of 1.2 x 10¹² n/cm²·sec. After cooling for 20 min, the irradiated lithium hydroxide was dissolved in distilled water. The resulting ¹⁸F was separated from the irradiated target by passing the lithium hydroxide solution successively through ion exchange columns of H-, OH- and H-forms. Use was also made of the Co-form ion exchange column in place of the H-form for the elimination of impurities. In the case of ⁶Li enriched lithium carbonate, the irradiated lithium carbonate was dissolved in hydrochloric acid, and ion exchange columns of Ag-, OH- and H-forms were used for purifying the ¹⁸F. The product ¹⁸F was obtained in the form of water containing ¹⁸F. The chemical yield for the purification of ¹⁸F was about 80% and the final radioactive impurities were less than 1 ppm. A neutron activation method for determining the isotopic abundance of ⁶Li was developed using the nuclear reactions ⁶Li(n, α)³H and ¹⁶O(t, n)¹⁸F. Aqueous solutions containing lithium were irradiated in pneumatic tube for 1 hr. ¹⁸F was separated by steam distillation from the irradiated solutions and precipitated as magnesium fluoride. The chemical yield for the separation of ¹⁸F was about 80%. The sensitivity limit was estimated to be 4 μg of natural lithium. (author)