黑色页岩铁同位素标准物质的研制

The Preparation of Reference Material for Fe Isotope Measurement of Black Shale Samples

本文选择宜昌三峡地区九龙湾剖面采集的黑色页岩作为黑色页岩Fe同位素备选标准物质,命名为CAGS-BS。使用单因素方差分析法对CAGS-BS进行均匀性检验;使用t检验对其在24个月中四次分析的数据进行长期稳定性的检验,结果显示均匀性和稳定性良好,满足标准物质的要求。黑色页岩Fe同位素标准物质采用多家实验室协作定值的方法确定特征量值。协作定值的单位包括:中国地质科学院地质研究所,中国科学技术大学,中国地质大学(北京),天津大学和中国科学院广州地球化学研究所。剔除了可疑值之后的数据符合正态分布,可以采用算术平均法进行标准物质的定值。标准物质不确定度由协作测定的不确定度分量(uchar)、批内瓶间差异引起的不均匀性不确定度分量(ubb’)和实验室保存引起的长期不稳定性不确定度分量(ults)共同确定,总不确定度为扩展不确定度,包含因子(k)等于2。得到CAGS-BS的特征值及不确定度为:δ^56FeIRMM-014/‰=0.10±0.04。该标准物质可用于黑色页岩样品的化学流程评价和验证、质谱仪的校正及整个过程的分析质量控制。

A new black shale reference material,named CAGS-BS,for use as Fe isotope ratio reference,has been prepared by Institute of Geology,Chinese Academy of Geological Sciences.One-way analysis of variance was used to test the homogeneity of CAGS-BS,and t-test was used to test the stability of CAGS-BS during 24 months(four times).CAGS-BS shows sufficient homogeneity and stability for use as an isotopic reference material.The reference value was determined by an interlaboratory comparison of results from five participating laboratories,which are Institute of Geology,Chinese Academy of Geological Sciences,University of Science and Technology of China,China University of Geosciences(Beijing),Tianjin University,and Guangzhou Institute of Geochemistry,Chinese Academy of Sciences.The property value was calculated from the unweighted means of the results submitted by the participating laboratories.The property value(δ^56FeIRMM-014/‰)for CAGS-BS is 0.10,with a combined expanded uncertainty(k=2)of 0.04.CAGS-BS can be used to validate chromatographic separation and total measurement procedures and to conduct inter-laboratory comparisons when Fe isotope of black shale samples is measured.