Interlaboratory comparison study of calibration standards for foraminiferal Mg/Ca thermometry
Interlaboratory comparison study of calibration standards for foraminiferal Mg/Ca thermometry
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DOI：
10.1029/2008gc001974
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发表时间：
2008-08-19
影响因子：
3.5
通讯作者：
Wilson, P. A.
中科院分区：
文献类型：
--
作者：
Greaves, M.;Caillon, N.;Wilson, P. A.
[1]在全球25个测定有孔虫Mg/Ca比值的实验室的参与下，对三种市售碳酸盐标准物质（BAM RS3、CMSI 1767和ECRM 752-1）中的Mg/Ca和Sr/Ca比值进行了实验室间研究。将这些含有有孔虫方解石范围内的Mg/Ca（0.8 mmol/mol至6 mmol/mol）的参比材料与溶解方案一起循环用于分析。要求参与者对粉末样品进行重复溶解，并使用实验室常规使用的仪器和校准标准品进行分析。根据国际标准化组织标准5725进行统计分析，该标准基于方差分析（ANOVA）技术。重复性（RSDr%），实验室内精密度的指标，为Mg/Ca测定溶液中的Mg/Ca后，增加减少Mg/Ca，从0.78%（Mg/Ca = 5.56 mmol/mol）至1.15%（Mg/Ca = 0.79 mmol/mol）。在离心溶液中测定Mg/Ca的重现性（RSDR%）（实验室间方法精密度的指标）明显差于重复性，范围从Mg/Ca = 5.56 mmol/mol时的4.5%至Mg/Ca = 0.79 mmol/mol时的8.7%。这项研究的结果表明，实验室间的变异性主要是仪器校准之间的不一致，并强调需要提高实验室间的兼容性。此外，该研究证实了这些固体标准品作为有孔虫Mg/Ca（和Sr/Ca）测定参考材料的适用性，前提是采用适当的程序以最大限度地减少和监测硅酸盐矿物相的可能污染。
[1] An interlaboratory study of Mg/Ca and Sr/Ca ratios in three commercially available carbonate reference materials (BAM RS3, CMSI 1767, and ECRM 752-1) was performed with the participation of 25 laboratories that determine foraminiferal Mg/Ca ratios worldwide. These reference materials containing Mg/Ca in the range of foraminiferal calcite (0.8 mmol/mol to 6 mmol/mol) were circulated with a dissolution protocol for analysis. Participants were asked to make replicate dissolutions of the powdered samples and to analyze them using the instruments and calibration standards routinely used in their laboratories. Statistical analysis was performed in accordance with the International Standardization Organization standard 5725, which is based on the analysis of variance (ANOVA) technique. Repeatability (RSDr%), an indicator of intralaboratory precision, for Mg/Ca determinations in solutions after centrifuging increased with decreasing Mg/Ca, ranging from 0.78% at Mg/Ca = 5.56 mmol/mol to 1.15% at Mg/Ca = 0.79 mmol/mol. Reproducibility (RSDR%), an indicator of the interlaboratory method precision, for Mg/Ca determinations in centrifuged solutions was noticeably worse than repeatability, ranging from 4.5% at Mg/Ca = 5.56 mmol/mol to 8.7% at Mg/Ca = 0.79 mmol/mol. Results of this study show that interlaboratory variability is dominated by inconsistencies among instrument calibrations and highlight the need to improve interlaboratory compatibility. Additionally, the study confirmed the suitability of these solid standards as reference materials for foraminiferal Mg/Ca (and Sr/Ca) determinations, provided that appropriate procedures are adopted to minimize and to monitor possible contamination from silicate mineral phases.