Abstract Sulfur isotope measurements by multi collector-inductively coupled plasma-mass spectrometry (MC-ICP-MS) require up to one hundred times less sulfur than traditional measurements via elemental analyzer isotope ratio mass spectrometry (EA-IRMS). Here, we report an improved MC-ICP-MS protocol for measuring δ34S values in different natural samples, specifically, calcium-sulfate minerals, carbonate associated sulfate, and dissolved sulfate in water. Sample preparation and subsequent anion exchange chromatography quantitatively recovers sulfur as sulfate. However, for samples with high and complex anion budgets, such as meteoric water, a stronger retention of sulfate on the anion exchange resin is observed relative to samples that contain sulfur as pure sulfate such as calcium-sulfate minerals and carbonate associated sulfate. An extended elution scheme with HNO3 is therefore required to achieve full recovery of sulfur, and thus accurate and reproducible δ34S values for the different materials investigated. Sulfur isotope measurements were performed on a Neptune Plus MC-ICP-MS coupled to an Apex-Ω desolvator, resulting in a “dry” plasma, negligible level of isobaric interferences, a sensitivity of >40 V ppm−1 sulfur, and a precision of 0.2‰ (2 S.D.) for δ34S for as little as 70 ng sulfur of a pure sulfate solution. The accuracy of the procedure was tested against duplicate δ34S EA-IRMS measurements for eleven different geologic samples. The EA-IRMS and MC-ICPMS values generally agree well within analytical uncertainty. However, procedural blank levels are on the order of a few tens of nanogram sulfur, and are thus the main limiting factor for accurate low-level sulfur isotope measurements with MC-ICP-MS.

中文翻译：

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电感耦合等离子体和气源质谱法对地质材料硫同位素测量的比较

摘要 通过多集电极电感耦合等离子体质谱法 (MC-ICP-MS) 测量硫同位素所需的硫含量比通过元素分析仪同位素比质谱法 (EA-IRMS) 进行的传统测量少一百倍。在这里，我们报告了一种改进的 MC-ICP-MS 协议，用于测量不同天然样品中的 δ34S 值，特别是硫酸钙矿物、碳酸盐伴生硫酸盐和水中溶解的硫酸盐。样品制备和随后的阴离子交换色谱定量回收作为硫酸盐的硫。然而，对于具有高且复杂的阴离子预算的样品，例如大气水，相对于含有硫作为纯硫酸盐（例如硫酸钙矿物和碳酸盐相关硫酸盐）的样品，观察到硫酸盐在阴离子交换树脂上的保留更强。因此，需要使用 HNO3 的扩展洗脱方案来实现硫的完全回收，从而使所研究的不同材料的 δ34S 值准确且可重现。硫同位素测量在与 Apex-Ω 去溶剂器耦合的 Neptune Plus MC-ICP-MS 上进行，产生“干”等离子体，同量异位干扰的水平可以忽略不计，硫的灵敏度 >40 V ppm-1，以及精确度对于低至 70 ng 硫的纯硫酸盐溶液，δ34S 为 0.2‰ (2 SD)。该程序的准确性针对 11 个不同地质样品的重复 δ34S EA-IRMS 测量值进行了测试。EA-IRMS 和 MC-ICPMS 值通常在分析不确定度范围内一致。然而，程序空白水平约为几十纳克硫，