Rare-earth elements (REEs) are known for their similar behaviors, which make their purification through chromatographic techniques particularly challenging. The use of α-hydroxyisobutyric acid (α-HIBA) in combination with a cation-exchange resin is perhaps the most widely used chromatographic technique to separate individual REEs from each other. However, only limited REE partition data between α-HIBA and cation resins exist, which makes it challenging to develop and optimize purification techniques using this platform. Here, we report distribution coefficients (K_d) of REEs, as well as Sr, Y, Ba, Th, and U, between α-HIBA at pH = 4.50 and AG50W-X8 cation-exchange resin, obtained by batch equilibration experiments. For all 19 elements, the distribution coefficients decrease with increasing acid concentration. For the REEs, a linear relationship is observed in log–log space between K_d values and α-HIBA molarity. While the K_d values have been calibrated at pH = 4.50, formulas are provided allowing recasting of the K_d values at any pH. To test the accuracy of the data, we compare elution curves simulated using the newly determined distribution coefficients to actual elution curves. The close agreement between simulated and experimental elution curves demonstrates that the distribution coefficients obtained in this study are effective to devise multielement extraction and purification scheme for high-precision elemental and isotopic analyses of REEs for various applications.

中文翻译：

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α-HIBA和AG50W-X8树脂之间的REE，Sr，Y，Ba，Th和U的分布系数

稀土元素（REE）以其相似的行为而闻名，这使得通过色谱技术进行纯化特别​​具有挑战性。将α-羟基异丁酸（α-HIBA）与阳离子交换树脂结合使用可能是最广泛使用的色谱技术，可将各个REE相互分离。但是，仅存在α-HIBA和阳离子树脂之间的有限REE分配数据，这使得使用该平台开发和优化纯化技术面临挑战。在这里，我们报告分布系数（K _d通过分批平衡实验获得的REE以及pH = 4.50的α-HIBA与AG50W-X8阳离子交换树脂之间的REE，Sr，Y，Ba，Th和U. 对于所有19种元素，分配系数均随酸浓度的增加而减小。对于稀土元素，线性关系在之间的双对数空间观察ķ _d值和α-HIBA摩尔浓度。虽然K _d值已在pH = 4.50时进行了校准，但提供的公式允许重铸K _d在任何pH值。为了测试数据的准确性，我们将使用新确定的分配系数模拟的洗脱曲线与实际洗脱曲线进行比较。模拟和实验洗脱曲线之间的密切一致性表明，本研究中获得的分布系数可有效地设计出适用于各种应用的稀土元素的高精度元素和同位素分析的多元素提取和纯化方案。