High yield separation of Cu-67 from irradiated zinc targets

The radionuclide 67Cu is still attracting considerable interest owing to its favorable nuclear properties for theranostics. It decays through the emission of a medium-energy β-particle (Eβ-=141keV ) and γ-radiation (Eγ =185keV), which makes it suitable for both therapy and diagnosis. Production of 67Cu is very challenging due to the very low cross-sections of all potential reactions. Generally, 67Cu can be produced using zinc targets eg. by 68Zn(p,2p) reaction, which requires high energy and high intensity proton beams and long irradiation times. Under these irradiation conditions, a variety of radionuclides are generated including 67Ga (T1/2=3.2617d), which presents the same γ-lines of 67Cu and heavily interferes with the measurement of 67Cu yield. This work was aimed at investigating a highly efficient separation process of Cu radioisotopes from the Zn target and, in particular, from the Ga impurities. Therefore, this procedure could be employed for the precise measurement of the nuclear cross-sections of the various possible routes to 67Cu production and for yield optimization studies. Ion-exchange solid phase extraction was employed as separation method.