Radioactive isotope separation with 3D-printed flow-based device

Radioactive isotope (RI) metals are a new type of tracer for positron emission tomography generated from the target metal by proton irradiation using a cyclotron. The generated metal RIs need to be separated from the target metal rapidly and effectively. In the present study, we developed a 3D-printed flow device to separate metal RIs from target metals. The separation was performed with selective formation of ethylenediaminetetraacetic acid (EDTA) complex based on the difference in formation constants. The RI metal selectively formed a EDTA complex, thus changing its ionic charge in solution. The solution was then introduced into a cation exchange column for selective adsorption of the target metal. The solution with added chelator and controlled pH was introduced into the developed system and automatically separated metal RI from target metals within 14 min. The separation method was applied to separate RI ⁶⁷Ga from target metal Zn using a mixture of 107 pg L^{-1 67}Ga in 250 mg L^-1 Zn²⁺. The recoveries of ⁶⁷Ga and Zn were 97% and 100%, respectively. Furthermore, an ultraviolet (UV) radiation reactor was integrated into the system to decompose the EDTA complex and recover the Ga³⁺ ion. Ga³⁺ recovery by UV radiation was effective, 87%. The developed system was also successfully applied to the separation of Zr and Y. Therefore, the method and system can be applied to separate other metal RIs from target metals.