Europium (Eu) has only two isotopes (¹⁵¹Eu and ¹⁵³Eu). As sequential rare earth elements, Eu and Gd do not easily separate from each other during column chromatography, making it difficult to measure accurate and precise Eu isotope ratio during mass spectral analysis. Eu isotope ratios can be determined by MC-ICP-MS using internal Sm or Gd spikes to correct for mass discrimination. In this report, we discuss and propose optimal conditions for precise and accurate Eu isotope ratio measurements in geological materials (igneous rock samples) using MC-ICP-MS. The NIST3117a ultrapure chemical reagent showed almost no Eu isotope fractionation regardless of the kind of isotope pair used in normalization. A pure Eu fraction with almost no Gd matrix extracted from rock samples also showed nearly the same degree of Eu isotope fractionation regardless of the isotope pair used in normalization. In the case of Eu fraction extracted from highly fractionated granite and high silica volcanic rocks, when ¹⁵⁴Gd interference relative to the internal ¹⁵⁴Sm standard exceeded ca. 0.1% (due to incomplete Eu separation), this Gd matrix effect created artifactual variation in Eu isotope ratios during MC-ICP-MS analysis. In order to obtain the best estimates of Eu isotope fractionation in geological samples, especially high silica rocks, our analytical methods require complete Eu separation without Gd matrix during sample preparation.

铕 (Eu) 只有两种同位素（¹⁵¹ Eu 和¹⁵³欧盟）。作为连续稀土元素，Eu 和 Gd 在柱层析过程中不易相互分离，使得在质谱分析过程中难以准确测量 Eu 同位素比。Eu 同位素比率可以通过 MC-ICP-MS 使用内部 Sm 或 Gd 尖峰来确定，以校正质量歧视。在本报告中，我们讨论并提出了使用 MC-ICP-MS 在地质材料（火成岩样品）中精确测量 Eu 同位素比值的最佳条件。无论在标准化中使用何种同位素对，NIST3117a 超纯化学试剂几乎没有显示出 Eu 同位素分馏。从岩石样品中提取的几乎没有 Gd 基质的纯 Eu 馏分也显示出几乎相同的 Eu 同位素分馏程度，而不管标准化中使用的同位素对如何。相对于内部¹⁵⁴ Sm 标准的¹⁵⁴ Gd 干扰超过了大约。0.1%（由于 Eu 分离不完全），这种 Gd 基质效应在 MC-ICP-MS 分析期间造成了 Eu 同位素比率的人为变化。为了获得地质样品，尤其是高硅岩石中 Eu 同位素分馏的最佳估计，我们的分析方法需要在样品制备过程中完全分离 Eu，而无需 Gd 基质。