Previous studies have shown that significant K isotope fractionation is found in continental weathering, oceanic crust subduction, and plant growth, suggesting that K isotopes could be a potentially important tracer. However, the complicated separation method and analytical conditions limit the precise analysis of potassium isotopes via MC-ICP-MS under “cold” plasma conditions. Here, an improved separation method (single column) permits the complete purification of K from the matrix elements. This method is efficient and convenient and achieves a high yield (99.5 ± 0.6%) and low blank (<10 ng K) under complex matrix extraction conditions. The high-resolution mode with a desolvating nebulizer system was used to increase the signal intensity of ⁴¹K⁺ and ³⁹K⁺ and reduce ³⁸ArH⁺, ⁴⁰ArH⁺, and some oxide/nitride interference. To eliminate scattered ions or secondary electrons, we used a new dummy bucket to collect high intensity ⁴⁰Ar⁺ beams. Besides, potassium isotopes for the standard SRM 3141a and new geological, environmental and biological reference materials such as DNC-1a, JMS-2, and GSB-14 were determined on a Nu Plasma 3 MC-ICP-MS instrument. Overall, the reproducibility of K isotope analysis was better than ±0.06‰ (2SD) that reported in most laboratories around the world. The measured δ⁴¹K values of the rock samples are homogeneous, consistent with the previous published data. However, the K isotope composition in soils, sediments, and plants is inhomogeneous and varies greatly from −0.85‰ to −0.25‰. These results show that potassium isotopes have great application potential in the geological, environmental, and biological fields.

中文翻译：

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带有模拟桶的MC-ICP-MS用于高精度K同位素分析的最佳分离方法

先前的研究表明，在大陆风化，大洋地壳俯冲和植物生长中发现了重要的K同位素分馏，这表明K同位素可能是潜在的重要示踪剂。但是，复杂的分离方法和分析条件限制了在“冷”血浆条件下通过MC-ICP-MS精确分析钾同位素的能力。在这里，一种改进的分离方法（单柱）可以从基质元素中完全纯化K。该方法高效便捷，在复杂的基质萃取条件下可实现高收率（99.5±0.6％）和低空白率（<10 ng K）。与脱溶剂喷雾器系统的高分辨率模式被用于以增加的信号强度⁴¹ ķ ⁺和³⁹ K ⁺并减少³⁸ ArH ⁺， ⁴⁰ ArH ⁺以及一些氧化物/氮化物干扰。为了消除散射的离子或二次电子，我们使用了一个新的虚拟桶来收集高强度的⁴⁰ Ar ⁺束。此外，在Nu Plasma 3 MC-ICP-MS仪器上测定了标准SRM 3141a的钾同位素以及新的地质，环境和生物学参考物质，例如DNC-1a，JMS-2和GSB-14。总体而言，钾同位素分析的重现性优于世界上大多数实验室报告的±0.06‰（2SD）。所测得的δ ⁴¹岩石样品的K值是均匀的，与先前发布的数据一致。然而，土壤，沉积物和植物中的钾同位素组成是不均匀的，并且在-0.85‰至-0.25‰之间有很大差异。这些结果表明钾同位素在地质，环境和生物领域具有巨大的应用潜力。