Sequential separation-to-purification of radioactive copper using a combination of flow electrolysis and ion transfer...

Preparation of the copper radioisotope ⁶⁴Cu (t_1/2 = 12.7 h) for use in positron emission tomography (PET) cancer diagnosis is an active area of research. This study describes a sequential separation and purification system that can quantitatively recover ⁶⁴Cu generated by irradiating a ⁶⁴NiO target with a proton beam, developed using a flow electrolysis device (FED) and electrodialysis ion-transfer device (ITD). The system operates as follows: (1) ⁶⁴Cu²⁺ dissolved by HCl is deposited on the carbon working electrode in the FED by applying -0.8 V and the coexisting stable Ni²⁺ is excluded; (2) the ⁶⁴Cu is eluted by 10 mmol/L HNO₃, applying +1.0 V to the FED; (3) the ⁶⁴Cu²⁺ is then injected into the sample channel in the ITD; and (4) transferred from the sample channel to the cation acceptor channel with 100 mM acetic acid, which is required to synthesize a labeled antibody in the PET, applying +40 V to the ITD. The final recovery of ⁶⁴Cu²⁺ was 96 ± 2 %. The developed process took 15 min to complete under the conditions used in this study. The picomolar levels of copper radioisotope were recovered from the large amount of target metal and transferred from strongly acidic to weakly acidic solution without a heating process.