A new simple and rapid method was developed for the purification of Ca from geological and biological samples. The proposed separation protocol is based on DGA resin and consists of only three elution steps and two types of eluents (6.8 mL 4 mol L⁻¹ HNO₃ and 3 mL DI-water), which afford a straightforward separation of Ca with a high yield (95–99%), good purity and low blank level. Moreover, a vacuum box was employed which enables Ca purification for a batch of twelve samples within two hours, with greatly improved efficiency compared to conventional gravity flow separation methods. Ca isotopic ratios were measured by multi-collector inductively coupled plasma mass-spectrometry (MC-ICP-MS) using a standard–sample bracketing method. Based on repeated measurements of NIST SRM 915a and Alfa Ca, the long-term reproducibility was evaluated at ±0.07‰ (2SD) for δ^44/42Ca. The validity of the proposed method was demonstrated by the analysis of thirteen international geological and biological reference materials with satisfactory results which are in good agreement with published values. Therefore, the proposed method can be used for a rapid and efficient determination of stable Ca isotopic ratios in geological and biological samples.

中文翻译：

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快速，简单的单步法从地质和生物样品中分离钙，通过MC-ICP-MS进行同位素分析†

开发了一种从地质和生物样品中纯化钙的简单而又快速的新方法。提议的分离方案基于DGA树脂，仅包含三个洗脱步骤和两种类型的洗脱液（6.8 mL 4 mol L ^-1 HNO ₃和3 mL去离子水），可直接分离Ca，产率高（95–99％），纯度高，空白水平低。此外，采用了真空箱，与常规重力流分离方法相比，该真空箱能够在两个小时内对一批十二个样品进行Ca纯化，效率大大提高。钙同位素比值通过多集电极电感耦合等离子体质谱法（MC-ICP-MS）使用标准样品包围法进行测量。基于NIST SRM 915A和阿尔法钙的重复测量，长期再现性在±0.07‰（2SD）评价δ ^44/42钙 通过对13种国际地质和生物参考资料的分析证明了该方法的有效性，其结果令人满意，与公开发表的值吻合良好。因此，该方法可用于快速有效地测定地质和生物样品中稳定的Ca同位素比。