Elemental Distribution Behavior of Sulfonic Acid Cation-Exchange Resins and Applications to High-precision Isotope Analysis

The distribution coefficient (K_d) of elements in ion exchange resin is the basis of element purification and separation, which is the premise for high-precision isotope analysis. However, systematic comparison of the K_d in different types of acid is lacking, which has hindered the development of efficient separation procedures for emerging isotope system. In this research, the K_d of 60 elements in AG^®50W-X8 cationic resin with different concentrations and types of acid was studied. Our results show that, in acid solutions, the K_d of almost all elements is negatively related to acidity. Compared to nitric acid, a significant decrease in the K_d for Al, Fe, Se, Pd, Cd, and In is observed in hydrochloric acid. The addition of hydrofluoric acid can significantly reduce the K_d of Be, Al, Sc, Fe, Sn, Th, U, Ti, Zr, and Hf in dilute hydrochloric and nitric acid, so that they can be quantitively eluted from the resin. In the mixed hydrofluoric acid solutions, K_dREE shows an initial increasing and then decreasing trend as the concentration of HCl increases. The present study provides data support for the development and optimization of element purification processes that are suitable for high-precision metal stable isotope analysis. The BRIEF REPORT is available for this paper at http://www.ykcs.ac.cn/en/article/doi/10.15898/j.ykcs.202309260154.