Development of an automated system for the quick production of 13N-labeled compounds with high specific activity using anhydrous [13N]NH3

An automated system was developed to synthesize 13N-labeled compounds with high specific activity using anhydrous [13N]NH3 as a synthetic precursor. This system enabled (1) production of an aqueous solution of [13N]NH3, (2) concentration and desiccation of the [13N]NH3 solution, (3) reaction of anhydrous [13N]NH3 with substrate, (4) purification and formulation. By the use of this system, [13N]p-nitrophenyl carbamate ([13N]NPC) ready for i.v. injection could be obtained in 5.1±0.1 min at the yield of 3.5±0.4 GBq, specific activity 460±55 GBq/μmol, and radiochemical purity >99% (n=3) by irradiating a 10 mM ethanol solution with 18 MeV protons at 17 μA for 25 min. With special precautions, [13N]NPC could be obtained at the extremely high specific activity of 1800±200 GBq/μmol.