Production of positron-emitting 110mIn via the 110Cd(3He, 3n)110Sn→110mIn process

Positron-emitting 110mIn was produced in a two-step process. Irradiation of highly enriched 110Cd with 3He-particles over an energy range of 36-25 MeV led to the formation of 110Sn, which after its fast radiochemical separation from the target material was used to prepare a 110Sn→110mIn generator. The radiochemical separation consisted of a thermochromatographic volatilization of 110SnCl4 from metallic 110Cd targets in a small quartz apparatus at 800 ± 10 °C within 20 min, followed by its removal from the quartz tube via dissolution in hydrochloric acid. The 110Sn separation yield was >98% and the fraction contained only < 10−4% of the target material. The solution was then transferred to a small Kieselgel 40 column to prepare a 110Sn→110In elution generator. The 110In was eluted quantitatively within 1 ml of 0.02 M hydrochloric acid. The only detectable isotopic impurity was 111In, generated from the co-formed 111Sn-contamination. Its percentage decreased from about 0.8% at 1 h after the end of bombardment to <0.01% at 7 h. The final solution was free of any traces of Cd. In the first experiments more than 15 mCi of 110mIn was delivered per generator.