Expanded uncertainty associated with determination of isotope enrichment factors: Comparison of two point calculation and Rayleigh-plot
Expanded uncertainty associated with determination of isotope enrichment factors: Comparison of two point calculation and Rayleigh-plot
复制标题
与同位素富集因子确定相关的扩展不确定性：两点计算和瑞利图的比较
DOI：
10.1016/j.talanta.2017.08.038
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发表时间：
2018
期刊：
影响因子：
6.1
通讯作者：
Gerald S. Remaud
中科院分区：
文献类型：
--
作者：
Maxime Julien;Alexis Gilbert;Keita Yamada;Richard J. Robins;Patrick Hohener;Naohiro Yoshida;Gerald S. Remaud
富集因子（ε）是表示与现象相关的同位素效应（IE）的常用方法。许多研究使用瑞利图确定ε，这需要多个数据点。最近的文章描述了一种使用瑞利方程的替代方法，该方法允许仅使用一个实验点来确定ε，但这种方法经常受到争议。然而，使用两个点（一个实验点和一个在t0处）的计算方法应该导致相同的结果，因为计算是从瑞利方程导出的。但是，经常有人问：“这两点计算的有效使用域是什么？”本工作的主要目的是系统地比较这两种方法获得的结果，并确定有效计算ε所需的条件。为了评估这两种方法的效率，与确定ε相关的扩展不确定度（U）已使用来自三篇已发表文章的实验数据进行了计算。本工作的第二个目标是描述如何确定与确定ε相关的扩展不确定度（U）。详细介绍了使用瑞利图和两点计算的比较方法，并且清楚地表明，使用单个数据点计算ε可以给出与瑞利图相同的结果，只要遵守一个严格的条件：在小部分未反应底物（f< 30%）下测量实验值。本研究将帮助稳定同位素用户以更严格的表达式ε ± U表示他们的结果，从而在解释之前更好地定义实验结果的显著性。胶囊：富集因子可以通过两种不同的方法确定，相关扩展不确定度的计算允许检查其显著性。
The enrichment factor (ε) is a common way to express Isotope Effects (IEs) associated with a phenomenon. Many studies determine ε using a Rayleigh-plot, which needs multiple data points. More recent articles describe an alternative method using the Rayleigh equation that allows the determination of ε using only one experimental point, but this method is often subject to controversy. However, a calculation method using two points (one experimental point and one at t0) should lead to the same results because the calculation is derived from the Rayleigh equation. But, it is frequently asked “what is the valid domain of use of this two point calculation?” The primary aim of the present work is a systematic comparison of results obtained with these two methodologies and the determination of the conditions required for the valid calculation of ε. In order to evaluate the efficiency of the two approaches, the expanded uncertainty (U) associated with determining ε has been calculated using experimental data from three published articles. The second objective of the present work is to describe how to determine the expanded uncertainty (U) associated with determining ε. Comparative methodologies using both Rayleigh-plot and two point calculation are detailed and it is clearly demonstrated that calculation of ε using a single data point can give the same result as a Rayleigh-plot provided one strict condition is respected: that the experimental value is measured at a small fraction of unreacted substrate (f< 30%). This study will help stable isotope users to present their results in a more rigorous expression: ε ± U and therefore to define better the significance of an experimental results prior interpretation.Capsule: Enrichment factor can be determined through two different methods and the calculation of associated expanded uncertainty allows checking its significance.