Radiochemical isolation of 45Ti using ion chromatography

Abstract

Abstract45Ti 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.