摘要
硅酸盐岩中含有微量的碳,对其精确地分析可以示踪流体的来源和形成过程。元素分析仪-同位素质谱方法(EA-IRMS)是一种使用样品量小、快速的分析方法,本文将EA-IRMS技术应用于硅酸盐岩中微量碳同位素组成的测定,基于一系列条件实验,确认了硅酸盐岩中微量碳分析的EA-IRMS连续流方法的关键条件参数。标准物质选择和归一化处理使用以下方法:(1)选择较宽碳同位素组成范围且合理的碳同位素分布的标准物质,以高纯石英粉末与之混合来模拟天然样品中的基质。(2)利用与样品类似含量的3个标准物质的测量值和标准真值建立校准曲线,对天然样品的测量值进行标准化,从而实现了对硅酸盐岩中低至600!g/g微量碳含量和同位素组成的精确测定。用国家标准物质GBW04416作为未知样品检验了不同含量下拟合的线性方程,在碳含量不低于600!g/g时,标准偏差分别约为0.02‰、0.04‰、0.05‰、-0.07‰、0.11‰;在MERCK+USGS24混合物中,测量的δ13C值在标准误差范围内与理论值是一致的。因此,对于碳含量不低于600!g/g的30 mg硅酸盐岩样品,本方法能够获得高精准度的碳同位素分析结果。根据不同碳含量的标准混合物的峰面积(峰强度)和相对应的含量所建立的线性曲线获得样品的碳含量,碳含量的分析误差在10%以内。
The precise and accurate analyses of minor carbon in silicate rocks can provide valuable insights into the origin of flui and formation processes. The Elemental Analyzer-Isotope Ratio Mass Spectrometry （ EA-IRMS） is a quick analytical method using small quantities of sample. In this study, EA-IRMS is applied to analyze carbon isotopic composition of trace carbon in silicate rock. Based on a series of tests, the key analytical parameters are confirmed. The normalization procedure and reference materials selection are as follows. （I） Selection of standard materials with a wide carbon isotope composition range and reasonable carbon isotope distribution. Preparation of the mixtures of reference materials and super quality quartz power. （2） A calibration curve was established using the measured values and certified values of the three reference materials similar to the samples. The measurement of natural samples is normalized to achieve an accurate determination of trace carbon content as low as 600 μg/g in silicate rocks and carbon isotopic composition. National standard material GBW04416 is used as an unknown sample to test the linear equations regressed with different contents. When the carbon content is no lower than 600 jixg/g, the standard deviations are 0. 02‰ , 0. 04‰ , 0. 05‰, - 0. 07‰, 0.11‰ , respectively. For the mixture of MERCK and USGS24, the determined carbon isotopic composition and carbon content are comparable with the true value within analytic uncertainty. Therefore, the high precision and accuracy of carbon isotopic composition can be obtained for carbon content no less than 600 μg/g in 30 mg silicate rock. The carbon content of the sample was established based on the linear curve established by the peak area （peak intensity） of the standard mixture of different carbon contents and the corresponding content. Analytic uncertainty of carbon content of the sample is within 10% .
作者
查向平
龚冰
郑永飞
ZHA Xiang-ping GONG Bing ZHENG Yong-fei(Key Laboratory of Crust-Mantle Materials and Environments, Chinese Academy of Sciences, School of Earth andSpace Sciences, University of Science and Technology of China, Hefei 230026, Chin)
出处
《岩矿测试》
CSCD
北大核心
2017年第4期327-339,共13页
Rock and Mineral Analysis
基金
中央高校基本科研业务费专项资金资助(WK3410000007)
关键词
元素分析仪
碳含量
碳同位素比值
硅酸盐岩
elemental analyzer
carbon concentration
carbon isotope ratio
silicate rocks
