Improved titanium-44 purification process for establishing a high apparent molar activity titanium-44/scandium-44 generator

Abstract

⁴⁴Sc-radiopharmaceuticals are gaining more interest but still lack availability. The proof of principle of a⁴⁴Ti/⁴⁴Sc generator, which can produce ⁴⁴Sc daily, has been established but with some limitations and drawbacks. Despite recent advances, separation of ⁴⁴Ti from massive quantities of scandium target material is still cumbersome. In this work, the improved radiochemical separation of ⁴⁴Ti from residual scandium target material was carried out by precipitation of Sc with fluoride ions. Furthermore, two approaches were used to set up a high apparent molar activity small-scale generator. The first method relied on extraction chromatography for fine purification using a DGA resin, followed by loading of the purified ⁴⁴Ti onto a ZR resin column. In the second method, ⁴⁴Ti was loaded on the ZR resin directly after the precipitation step. This second method was used to set up a generator of 370 kBq and evaluate by radiolabeling. An apparent molar activity of 2 MBq/nmol was obtained for the radiolabeling with DOTA, the most common and suitable chelate for scandium. This result is comparable with previously published data on ^44 m/44Sc.