Hierarchical macro/mesoporous γ-Al₂O₃ as column matrix for development of low specific activity ⁹⁹Mo/^99mTc generator via ¹⁰⁰Mo (γ, n)⁹⁹Mo reaction

Abstract 99m Tc, the daughter product of 99 Mo, is a γ-emitting radionuclide with essential diagnostic applications in nuclear medicine. In this paper, an accelerator-based method ( 100 Mo (γ, n) 99 Mo) for production of 99 Mo and 99m Tc has been explored. Approximately 68.3 MBq of 99 Mo was successfully produced by the irradiation of 100 Mo metallic target for 40 h using electron beam with energy of 50 MeV and current of 0.2 μA at electron linear accelerator (Institute of Modern Physics, Chinese Academy of Sciences, IMPCAS). Different types of 99 Mo/ 99m Tc generators were prepared using hierarchical macro/mesoporous γ-Al 2 O 3 (HMMA) as column adsorbent, and their performances were evaluated for over one week. 99 Mo/ 99m Tc generator with a column (3 mL, 4.2 × 0.95 cm) packed with 0.6 g HMMA exhibited excellent eluting performance. 99m Tc could be collected within 4.0 mL of saline solution with high purity, and the elution efficiency could reach >85 %. Furthermore, 99 Mo breakthrough in the eluates was negligible (<2 × 10 −3 %) and concentration of impurity (<10 ppm) was acceptable. Finally, the enriched 100 Mo was eluted from the spent 99 Mo/ 99m Tc generator using 1.0 mol/L ammonium hydroxide, and then reduced by high-temperature hydrogen reduction process with a total recovery of 95.3 %. This work demonstrated that the preparation of 99 Mo via 100 Mo (γ, n) 99 Mo reaction and isolating 99m Tc using HMMA column chromatography have a potential in application.