Radiochemical isolation of ⁴⁵Ti using ion chromatography

⁴⁵Ti exhibits favorable decay properties for positron emission tomography (PET) imaging and can be easily produced by the bombardment of natural scandium (Sc) by protons using the ⁴⁵Sc(p,n)⁴⁵Ti nuclear reaction. However, separation of ⁴⁵Ti from irradiated Sc targets is arduous due to the hydrolytic instability of Ti(IV) complexes, making it a significant bottleneck for routine application of this radionuclide. In the present work, we describe the development and optimization of an ion chromatographic separation method based on trapping of ⁴⁵Ti on a hydroxamate-functionalized chelating resin and subsequent elution with oxalic acid at pH = 2.8. Under optimized conditions, this method enabled ⁴⁵Ti-recovery of 61 ± 8% within 7 min. Sc contamination in scaled-up experiments was found to be only 3.0 ± 1.8 µg/mL. The resulting ⁴⁵Ti-solution was directly used for complexation with CDTA as a model chelator, affording the corresponding [⁴⁵Ti]Ti(cdta) complex with a radiochemical conversion of 73 ± 3%. Conclusively, this promising method could be transferred to automated synthesis modules and should enable the preparation of ⁴⁵Ti-labeled compounds for PET imaging.