KCS

The no-carrier added (nca) lutetium-177 (¹⁷⁷Lu, t_1/2 = 6.7 d) are a promising therapeutic radionuclide in nuclear medicine because it has high specific radioactivity and high radionuclide purity without long-lived radioactive impurity. The nca ¹⁷⁷Lu can be produced via the ¹⁷⁶Yb(n,γ)¹⁷⁷Yb → ¹⁷⁷Lu reaction, where the process of separating it from a macroscopic amount of Yb target is important. Ion exchange chromatography is generally used to separate two adjacent nuclides Yb and Lu, with α-HIBA (α-hydroxyisobutyric acid) as complexing agent and NH₄⁺ (ammonium hydroxide) as separating ion. Numerous papers evaluating the separation efficiency have studied the effect of the concentration of the eluent, but few papers have evaluated the separation efficiency using separating ion other than normal NH₄⁺ ion. Thus, in this study, the separation efficiency of stable isotopes Yb and Lu was evaluated by using different ammonium ions, including primary, secondary and tertiary ammonium ions, replacing NH₄⁺ ion. Separation experiments were carried out using α-HIBA with pH adjusted using ammonium hydroxide, methylamine, ethylamine, diethylamine, pyridine, ethanolamine and ethylenediamine, respectively. Since the column retention time and elution time increase as the amine order increases, it is important to select an appropriate type of ammonium ion for effective and selective separation of Yb and Lu.