磁铁矿LA-ICP-MS原位微量元素分析方法研究

激光剥蚀电感耦合等离子体质谱(LA-ICP-MS)技术在矿物微量元素分析方面具有原位、高分辨率和高灵敏度等优势,近年来磁铁矿LA-ICP-MS原位微量元素研究进展迅速,并在地质领域得到了广泛应用。利用长安大学成矿作用及其动力学实验室Agilent 7700X四极杆等离子体质谱和Photo Machines Analyte Excite 193 nm激光,建立了LA-ICP-MS测定磁铁矿原位微量元素组成的分析方法。以美国地质调查局(USGS)玻璃标样BIR-1G、BHVO-2G、BCR-2G和GSE-1G为校正标准,采用无内标-多外标法对磁铁矿中微量元素进行了定量计算,并测定了NIST612和自然岩浆磁铁矿BC28的微量元素组成,以评估本实验室建立方法的可靠性。结果表明,NIST612所有微量元素的相对标准偏差(RSD,N=30)变化于1.31%~6.33%之间,多数元素的测定结果与推荐值及前人LA-ICP-MS方法测定值的相对误差小于10%;BC28大部分微量元素的相对标准偏差(RSD,N=30)小于10%,其中11个重要微量元素与前人LA-ICP-MS测定值的相对误差基本小于10%。以上结果表明本实验室建立的方法可以实现对磁铁矿原位微区微量元素的分析测定,分析数据结果准确可靠,具有良好的应用前景。

Analysis method for in-situ trace element determination of magnetite by LA-ICP-MS

Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) method is characterized by in-situ, high space resolution and high sensitivity. Therefore, the study of LA-ICP-MS in-situ trace elements analysis in magnetite has made a rapid progress and it is widely used in geological field in recent years. An analytical method for the trace elements determination of magnetite by LA-ICP-MS using Agilent 7700X inductively coupled plasma-mass spectrometry (ICP-MS) and Photo Machines Analyte Excite 193nm laser ablation was established at the laboratory of mineralization and dynamics, Chang′an University. This method adopts multiple external standards (BIR-1G, BHVO-2G, BCR-2G and GSE-1G) as calibration standards without an internal standard. Trace element compositions of the glass standard material NIST 612 and natural magmatic magnetite BC 28 were determined by the established method to evaluate its reliability. The results show that the relative standard deviation (RSD, N=30) of trace elements in NIST 612 ranges from 1.31% to 6.33%. Compared with the recommended values and the previous reference values obtained by LA-ICP-MS, the relative error of most elements in NIST 612 is smaller than 10%. The RSD (N=30) of most elements in BC 28 is lower than 10%, and the relative error of 11 important trace elements in BC 28 is smaller than 10% compared with the reported values by LA-ICP-MS. The above results show that in-situ trace element determination of magnetite can be carried out by using the method established in this study. The analysis data is accurate and reliable, and it has a great application potential.