Radiochemical and chemical quality-assurance methods for [13N]-ammonia made from a small volume H2(16)O target

HPLC and TLC systems were sought for routine assurance of [13N]NH3 for human PET studies. An ion chromatograph with conductivity and radioactivity detection was used to confirm that [13N]NO2- and [13N]NO3- were the major 13N species formed by the 16O(p, alpha)13N reaction in a small volume (0.5 mL) water target irradiated with protons (24 MeV), and that Devarda's alloy reduction and distillation in an apparatus constructed of disposable components and requiring no external heating gave radiochemically and radionuclidically pure [13N]NH3. Merck polyethylene-backed TLC plates were developed in the upper phase of the solvent mixture: H2O/acetone/propionic acid (6:4:2, v/v) saturated with NaCl. The Rf of [13N]NH3 was 0.6. HPLC was conducted with a 25 X 0.46 cm column with 2 mL/min CH3CN/10 mM aqueous sodium 1-octanesulfonate (1:2, v/v). [13N]NH3 eluted at 3.5 min.