Cyclotron production and radiochemical separation of 55Co and 58mCo from 54Fe, 58Ni and 57Fe targets

This work presents the production with a cyclotron of the positron emitter 55Co via the 54Fe(d,n) and 58Ni(p,α) reactions and the Auger electron emitter 58mCo via the 57Fe(d,n) reaction after high current (40 μA p and 60 μA d) irradiation on electroplated targets. High specific activity radionuclides (up to 55.6 GBq/μmol 55Co and 31.8 GBq/μmol 58mCo) with high radionuclidic purity (99.995% 55Co from 54Fe, 98.8% 55Co from 58Ni, and 98.7% 58mCo from 57Fe at end of bombardment, EoB), in high activity concentration (final separated radionuclide in < 0.6 mL) and with almost quantitative overall activity separation yield (> 92%) were obtained after processing of the irradiated targets with novel radiochemical separation methods based on HCl dissolution and the resin N,N,N′,N′-tetrakis-2-ethylhexyldiglycolamide (DGA, branched). One hour long irradiations using 38-65, 110-214 and 59-78 mg of enriched 54Fe (99.93%), 58Ni (99.48%) and 57Fe (95.06%), respectively, electroplated over a 1.0 cm2 surface, yielded 582 ± 66 MBq 55Co, 372 ± 14 MBq 55Co and 810 ± 186 MBq 58mCo, respectively, decay corrected to EoB. The separation methods allow for the recovery of the costly enriched target materials, which were reconstituted into metallic targets after novel electroplating methods, with an overall recycling efficiency of 93 ± 4% for iron. The produced radionuclides were used to radiolabel the angiogenesis marker antibody TRC105 conjugated to the chelator NOTA as a demonstration of their quality.