Interlaboratory comparison of boron isotope analyses of boric acid, seawater and marine CaCO3 by MC-ICPMS and NTIMS
Interlaboratory comparison of boron isotope analyses of boric acid, seawater and marine CaCO3 by MC-ICPMS and NTIMS
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DOI：
10.1016/j.chemgeo.2013.08.027
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发表时间：
2013-11-04
期刊：
影响因子：
3.9
通讯作者：
Vengosh, Avner
中科院分区：
文献类型：
--
作者：
Foster, Gavin L.;Hoenisch, Baerbel;Vengosh, Avner
在这项研究中，我们首次尝试对四个不同的实验室测量的海洋生物成因碳酸盐的硼同位素(增量B-11)进行内部校准，每个实验室使用不同的分析技术。这种校准的重要性在于B-11三角洲相对较小的变化(2%)的主要含义，这是B-11-pH代用品在古气候中的典型应用。尽管本研究中不同实验室使用了不同的质谱学技术(负离子热电离质谱仪的两种变体和多收集器电感耦合等离子体质谱的两种变体)，但对于没有复杂样品基质的样品，如硼酸，没有明显的实验室间偏差：这些样品的2SD汇集为千分之0.39，这在每个实验室报告的测量不确定度范围内(范围在0.18至0.80%之间)。对于海水这一常见的内部参考物质，我们发现尽管有四种不同的样品制备程序，但仍有类似的良好一致性(Delta B-11=39.65+/-0.41%，2SD)。报告的碳酸钙样品的增量B-11的混合2SD为1.46%，大于每个实验室报告的测量不确定度。我们试图确定这种实验室间变异性的来源，并发现总体样本量(根据可用B)和B/Ca比率(即相对于基质的硼量)可能起到一定作用，但确切的机制仍不确定。然而，所报告的CaCO3样品的增量B-11的观测变化对于每个实验室对于给定的样品基质来说是相对系统的(即相似的B/Ca和用于分析的硼量)。这意味着，参与这项研究的四个实验室可以比绝对的硼同位素比率更准确地重建给定基质样本集中的增量B-11的相对差异。(C)2013爱思唯尔B.V.保留所有权利。
In this study we make the first attempt to inter-calibrate boron isotope (delta B-11) measurements on marine biogenic carbonates measured by four different laboratories, each using a different analytical technique. The importance of such calibrations lies in the major implications of relatively small changes in delta B-11 (< 2%), which are typical of palaeoclimate applications of the delta B-11-pH proxy. Despite the variety of mass spectrometric techniques used by the different laboratories in this study (two variants of negative ion thermal ionisation mass spectrometry and two variants of multicollector inductively coupled plasma mass spectrometry), for samples without a complex sample matrix, such as boric acid, there are no significant interlaboratory biases: the pooled 2sd of these samples is 0.39 parts per thousand, which is within the measurement uncertainties reported by each laboratory (which range between 0.18 and 0.80%). For seawater, a common in-house reference material, we find a similarly good agreement (delta B-11 = 39.65 +/- 0.41%, 2sd) despite four different sample preparation procedures. Reported delta B-11 for calcium carbonate samples have a pooled 2sd of 1.46%, which is larger than the measurement uncertainty reported by each laboratory. We have attempted to identify the source of this interlaboratory variability, and find that overall sample size (in terms of available B) and B/Ca ratio (i.e. amount of boron relative to matrix) may play a role, but the exact mechanisms remain uncertain. Observed variations in reported delta B-11 for the CaCO3 samples are, however, relatively systematic for each laboratory for a given sample matrix (i.e. similar B/Ca and amount of boron for analysis). This implies that relative differences in delta B-11 in a sample set of a given matrix can be reconstructed by the four laboratories involved in this study more accurately than the absolute boron isotope ratios. (C) 2013 Elsevier B.V. All rights reserved.