Effects of different cone combinations on accurate and precise determination of Li isotopic composition by MC-ICP-MS
Effects of different cone combinations on accurate and precise determination of Li isotopic composition by MC-ICP-MS
复制标题
不同锥体组合对 MC-ICP-MS 准确测定锂同位素组成的影响
DOI：
10.1016/j.sab.2018.04.015
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发表时间：
2018-08-01
影响因子：
3.3
通讯作者：
Liu, Chun-Yao
中科院分区：
文献类型：
--
作者：
Gou, Long-Fei;Jin, Zhang-Dong;Liu, Chun-Yao
多收集器电感耦合等离子体质谱(MC-ICP-MS)是一种高精度、快速、准确的锂(Li)同位素测量仪器。改进的高灵敏度喷射样品和X撇油器锥体大大提高了分析灵敏度，降低了样品消耗，具有明显的仪器质量偏差行为。本文测试了四种样品锥和撇油锥的组合[喷射样品锥+X撇油锥(Jet+X)、标准样品锥+X撇油锥(Standard+X)、标准样品锥+H撇渣锥(Standard+H)和喷射样品锥+H撇渣锥(Jet+H)]对溶液模式下锂同位素测量的峰形、灵敏度、质量偏差行为以及准确度和精密度的影响。结果表明，通过调整相关参数，四种组合都能获得理想的峰形，Li-7(和Li-6)信号与Li浓度呈线性正相关。对于给定的Li浓度，使用标准+X、Jet+H和Jet+X组合比使用标准+H的灵敏度提高3-7倍。提高灵敏度是由于更多的等离子体离子通过Jet和X锥体引入质谱仪。不同的锥体组合有不同的质量偏差，不同Li浓度的质量偏差略有不同，说明测量过程中浓度匹配的必要性。在四种锥体组合中，以标准+X锥体测定样品的精密度和准确度最好。此外，在分析前先用5%的HNO_3和0.1%的HF进行预处理，然后再用2%的HNO_3进行分析，可以使Li的记忆效应降到最低。(C)2018爱思唯尔B.V.保留所有权利。
The multiple collector inductively coupled plasma mass spectrometer (MC-ICP-MS) is booming to be a high-precision, fast, and accurate instrument in measuring lithium (Li) isotopes. Modified highly sensitive Jet sample and X skimmer cones have largely upgraded analytical sensitivity and reduced sample consumption with distinct instrumental mass bias behaviors. Herein, four available combinations of the sample and skimmer cones [Jet sample cone + X skimmer cone (Jet + X), Standard sample cone + X skimmer cone (Standard + X), Standard sample cone + H skimmer cone (Standard + H), and Jet sample cone + H skimmer cone (Jet + H)] were tested for their effects on peak shape, sensitivity, mass bias behavior, and accuracy and precision of Li isotopic measurements in solution mode. The results showed that all four combinations were able to attain an ideal peak shape by adjusting the associated parameters, with a positively linear relation between Li-7 (and Li-6) signals and Li concentrations. For a given Li concentration, the sensitivities were enhanced 3-7 times using the Standard + X, the Jet + H, and the Jet +X combinations compared to that of using the Standard + H. The enhanced sensitivity is attributable to more plasma ions introduced into the mass spectrometer through the Jet and X cones. Mass bias is distinct for different cone combinations, with a slight difference with various Li concentrations, indicating the neccesity of concentration match during measurement. Among the four cone combinations, the best reproducibility can be obtained by using the Standard + X cones to determine precise and accurate Li isotopes for samples. Furthermore, a pretreatment by 5% HNO3 and 0.1% HF, and then 2% HNO3 prior to analyses can minimize the memory effect of Li. (C) 2018 Elsevier B.V. All rights reserved.