Measuring ⁸⁷Sr/⁸⁶Sr ratios with MC-ICP-MS is a straightforward technique due to its fast sample introduction. However, excellent accuracy and precision cannot be easily achieved unless careful optimization of plasma running conditions and evaluation of instrumental mass bias are conducted. Here, we developed an optimized protocol for measuring ⁸⁷Sr/⁸⁶Sr ratios using a modified cone arrangement (H skimmer cone + Jet sample cone) by carefully examining the effects of plasma working conditions on the performance of Sr isotope analysis with a Neptune Plus™ MC-ICP-MS. The modified cone arrangement significantly enhanced the Sr signal sensitivities by a factor of 2, compared to the standard cone arrangement (H skimmer cone + standard sample cone). For both cone arrangements, the mass bias of Sr isotopes fits the standard exponential law under optimal conditions. However, at non-optimum sample gas flow rates, the corrected ⁸⁷Sr/⁸⁶Sr ratios deviated from the reference value, and thus non-linear mass bias was observed. Such mass bias could not be corrected using the standard exponential law. This observation cautioned researchers analyzing Sr ratios at optimized sample gas flow rates when using MC-ICP-MS. With further evaluation of the sample concentration, integration time and interference element correction, ⁸⁷Sr/⁸⁶Sr ratio analysis with high accuracy and precision was achieved. Excellent results of the reference materials were obtained using the optimized protocol. Compared to the classical TIMS technique, our method is comparable in precision (∼8 × 10⁻⁶, 2SE) but much faster in operation (14 minutes per analysis), and therefore is a technical advance in Sr isotope geochemistry.

中文翻译：

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使用Neptune Plus多收集器电感耦合等离子体质谱仪进行87Sr / 86Sr高精度测量的优化协议：评估不同锥体组合以测定Sr同位素。

由于MC-ICP-MS快速引入样品，因此用它来测量⁸⁷ Sr / ⁸⁶ Sr比是一项简单的技术。但是，除非仔细地优化等离子体运行条件和评估仪器的质量偏差，否则无法轻易获得出色的精度和精密度。在这里，我们开发了一种用于测量⁸⁷ Sr / ⁸⁶的优化协议通过使用Neptune Plus™MC-ICP-MS仔细检查等离子体工作条件对Sr同位素分析性能的影响，使用改进的圆锥布置（H分离器圆锥+ Jet样品圆锥）来获得Sr比率。与标准圆锥布置（H分离器圆锥+标准样品圆锥）相比，改进的圆锥布置将Sr信号灵敏度显着提高了2倍。对于两个圆锥体布置，Sr同位素的质量偏差在最佳条件下均符合标准指数定律。但是，在非最佳样品气体流速下，校正后的⁸⁷ Sr / ⁸⁶Sr比偏离参考值，因此观察到非线性质量偏差。使用标准指数定律无法纠正这种质量偏差。该观察结果提醒研究人员在使用MC-ICP-MS时应以最佳的样品气体流速分析Sr比率。通过进一步评估样品浓度，积分时间和干扰元素校正，可以实现高精度和高精度的⁸⁷ Sr / ⁸⁶ Sr比分析。使用优化的方案可获得参考材料的优异结果。相较于传统技术TIMS，我们的方法是在精度（〜8×10可比^-6，2SE），但在操作快得多（每次分析14分钟），并因此是在锶同位素地球化学一个技术进步。