A test of comparative equilibration for determining non-exchangeable stable hydrogen isotope values in complex organic materials
A test of comparative equilibration for determining non-exchangeable stable hydrogen isotope values in complex organic materials
复制标题
DOI：
10.1002/rcm.4150
复制
发表时间：
2009-08-01
影响因子：
2
通讯作者：
Wassenaar, Leonard I.
中科院分区：
文献类型：
--
作者：
Kelly, Jeffrey F.;Bridge, Eli S.;Wassenaar, Leonard I.
比较平衡已被提议作为一种方法学途径，用于确定复杂有机材料（从羽毛到血液和土壤）中不可交换氢的氢同位素组成（Δ D）。该方法依赖于使用均质化标准品，这些标准品先前已针对其不可交换H的Δ D值进行了校准，其组成与未知样品相似，并且跨越适当的同位素范围。目前还没有可交换氢的有机标准物质，因此要求同位素实验室开发临时内部校准标准品，例如目前用于动物迁移研究的角蛋白标准品。不幸的是，一些样品的同位素比落在目前用于比较平衡的角蛋白标准品的范围之外。在这里，我们测试了一组五个均匀的角蛋白粉末，以及羽毛从彩斑和黑眼容科斯，以确定外推比较平衡归一化方程的角蛋白标准的同位素范围之外的影响。我们发现，（1）比较平衡在校准标准品范围内给出了精确的结果;（2）归一化方程的线性外推产生了精确的Δ D结果，接近于所用角蛋白标准品范围外的千分之40（-187至-108）;以及（3）对于均质化的角蛋白粉末和不均匀的未知样品，在角蛋白含量范围内和范围外的样品之间的方差没有差异，标准这表明，比较平衡法是测定复杂有机基质Δ D的一种稳健实用的方法，但对于远远超出校准范围的样品需要谨慎。版权所有（C）2009约翰威利父子有限公司
Comparative equilibration has been proposed as a methodological approach for determining the hydrogen isotopic composition (delta D) of non-exchangeable hydrogen in complex organic materials, from feathers to blood and soils. This method depends on using homogenized standards that have been previously calibrated for their delta D values of non-exchangeable H, that are compositionally similar to unknown samples, and that span an appropriate isotopic range. Currently no certified organic reference materials with exchangeable H exist, and so isotope laboratories have been required to develop provisional internal calibration standards, such as the keratin standards currently used in animal migration studies. Unfortunately, the isotope ratios of some samples fall outside the range of keratin standards currently used for comparative equilibration. Here we tested a set of five homogenized keratin powders as well as feathers from Painted Buntings and Dark-eyed Juncos to determine the effects of extrapolating comparative equilibration normalization equations outside the isotopic range of keratin standards. We found that (1) comparative equilibration gave precise results within the range of the calibration standards; (2) linear extrapolation of normalization equations produced accurate delta D results to similar to 40 parts per thousand outside the range of the keratins standards used (-187 to -108); and (3) for both homogenized keratin powders and heterogeneous unknown samples there was no difference in variance between samples within and outside the range of keratin standards. This suggested that comparative equilibration is a robust and practical method for determining the delta D of complex organic matrices, although caution is required for samples that fall far outside the calibration range. Copyright (C) 2009 John Wiley & Sons, Ltd.