A Chromatographic\nApproach for High-Precision Eu Isotope\nAnalysis

Eu isotopes are promising tracers across various scientific\ndomains\nsuch as planetary, earth, and marine science, yet their high-precision\nanalysis has been challenging due to the similar geochemical properties\nof rare earth elements (REEs). In this study, a novel two-column chromatographic\napproach was developed utilizing AG50W-X12 and TODGA resins to separate\nEu effectively from matrix and interfering elements like Ba, Nd, Sm,\nand Gd, while ensuring high Eu yields (99.4 ± 0.4%, <i>n</i> = 19) and low blanks (<20 pg). The robustness of this method\nis evidenced by various rock types and different Eu loading masses.\nThe efficient purification of Eu facilitated the establishment of\na high-precision calibration technique with standard-sample bracketing\n(SSB) and internal normalization (Nd). When a Nu Plasma 1700 multicollector-inductively\ncoupled plasma-mass spectrometry (MC-ICP-MS) instrument was employed,\nrepeated purification and analysis of various Geological Reference\nMaterials (GRMs) confirmed that the long-term external precision of\nδ<sup>153/151</sup>Eu is better than 0.04‰ (2 standard\ndeviation (2SD)), which represents a 2–5-fold increase in precision\ncompared to previously reported methods. Additionally, the high-precision\nEu isotopic compositions of five GRMs, including basalts, andesite,\nsyenite, and marine sediment, were measured. The high-precision Eu\nisotope techniques presented herein open up new avenues for Eu isotope\ngeochemistry.