高精度硅同位素分析方法研究进展

Progress in High Precision Analytical Approaches of Silicon Isotope

基于碱熔法的改进和多接收电感耦合等离子质谱仪(MC-ICP-MS)的发展,近年来高精度Si同位素组成(δ30Si)分析方法取得了长足进步,分析精度(2SD)自气体质谱仪(GS-MS)时代的±0.15‰~±0.30‰提高到优于±0.10‰,足以辨析高温过程中Si同位素发生的微小分馏,并且避免了实验流程中使用含氟等危险化学品。二次离子质谱(SIMS)和飞秒激光剥蚀(fs LA)的发展使得原位Si同位素组成分析精度近期也优化到±0.10‰~±0.22‰。文章对近年来Si同位素分析方法的发展沿革进行综述,探讨建立溶液法MC-ICP-MS的高精度Si同位素分析方法的进展与局限,并比对了国内外各个实验室已发表国际国内Si同位素标准物质测定值,最后总结了硅酸盐地球(BSE)、地壳和陨石等主要地质储库的δ^(30)Si组成范围。

With the modification of Alkali fusion method for digesting silicates and the development of the multi-collection inductively coupled plasma mass spectrometer(MC-ICP-MS),the silicon isotopic analysis methods have been significantly improved in recent years.The analytical precision ofδ30Si(2SD)is better than±0.10‰,compared with±0.15‰-±0.30‰by gas mass spectrometer(GS-MS)in earlier studies.It enables us to distinguish the minor fractionation of Si isotopes during the high temperature processes;and also avoid using hazardous chemical such as fluoride.For the in situ determination ofδ30Si,the analytical precision of secondary ion mass spectrometry(SIMS)and femtosecond laser ablation(fs LA)also have been modified to be±0.10‰-±0.22‰.This article reviewed the progress in silicon isotope analysis in the past decades,and discussed the establishment of high precision silicon isotope analysis method under wet plasma condition using MC-ICP-MS.Then we compared the silicon isotopic compositions of standard reference materials in different laboratories,and finally summarized the range ofδ^(30)Si in major geological reservoirs,e.g.,BSE,Earth crust and Meteorites.