摘要
采用193 nm准分子激光与MC-ICP-MS质谱仪探讨了原位微区分析过程中物质基体效应对铅同位素测定的影响,指出选择基体匹配标准物质对测定硫化物铅同位素具有重要意义。通过模拟计算发现准确测定Tl与Hg的分馏因子关系,可以在204Hg/204Pb<2的范围内有效校对204Hg对204Pb的干扰。研究表明,束斑直径(24~160μm)和剥蚀频率(2~20 Hz)并不影响铅同位素组成测试。改变激光剥蚀参数可以解决MC-ICPMS信号检测范围较窄的问题。针对目前硫化物固体标准物质缺乏的现状,采用压片法和快速熔融法制备硫化物标准物质。压片样品铅同位素组成表现出较好的均一性,而不同批次快速熔融法样品存在铅同位素分馏,仅单次制造的熔融样品内部铅同位素组成具有均匀性。结果表明,虽然快速熔融法还存在一定缺陷,但这两种方法都有望成为硫化物标准样品制作方法的备选方案。利用本方法对天然硫化物样品(黄铁矿和闪锌矿)及人工合成硫化物样品的铅同位素组成进行了准确测定,测定值与溶液值在误差范围内一致。
Pb isotope is an important geochemical tracer in the study of ore-forming material source,mineralization process and deposit formation mechanism.In this study,the matrix effect on Pb isotope determination by 193 nm excimer laser and multiple collector inductively coupled plasma mass spectrometry（MC-ICP-MS） was investigated,and the results showed that it was of importance to select an appropriate matrix matching standard material for determination of Pb isotope composition in sulfide.By the simulation,it was found that the accurate determination of Tl and Hg fractionation factor could effectively correct the interference of ^204Hg-^204Pb in the range of ^204Hg/^204Pb〈2.It was also found that the spot size（24-160 μm） and the pulse frequency（2-20 Hz） did not affect the Pb isotope analysis,so changing the laser ablation parameters could solve the problem of narrow detection range for MC-ICP-MS.To solve the lack of sulfide solid standard materials,the preparation of sulfide standard materials by pressing and rapid melting method was attempted.The pellet samples showed a good homogeneity of Pb isotope composition.For the rapid melting method,there was Pb isotope fractionation in different batches.But the homogeneous Pb isotopic composition was found in the single-batch molten samples.The results showed that these two methods were promising candidates for the preparation of sulfide standard samples,though the rapid melting method needed to be further modified.The Pb isotopic compositions in natural sulfide samples（pyrite and sphalerite） and synthetic sulfides were determined by the established method.The measured values were consistent with the solution values in the error range.
出处
《分析化学》
SCIE
EI
CAS
CSCD
北大核心
2017年第1期14-22,共9页
Chinese Journal of Analytical Chemistry
基金
国家自然科学基金面上项目(No.41573015)
中国博士后科学基金面上项目(No.2015M580677)资助~~
