Standardization for 13C‐13C clumped isotope analysis by fluorination method
Standardization for 13C‐13C clumped isotope analysis by fluorination method
复制标题
氟化法 13C-13C 簇同位素分析的标准化
DOI：
10.1002/rcm.9109
复制
发表时间：
2021
影响因子：
2
通讯作者：
Ueno Yuichiro
中科院分区：
文献类型：
--
作者：
Taguchi Koudai;Gilbert Alexis;Ueno Yuichiro
C2分子的13 C-13 C同位素最近已经使用一种同位素方法测量。首先将C2化合物氟化为六氟乙烷（C2 F6），随后使用传统的同位素比质谱仪测量其13 C-同位素体。在这里，我们提出了一种方法来标准化的绝对参考规模的同位素富集C2F6.MethodsWe标记的乙醇和天然乙醇的13 C-13 C-制备的物理混合物的同位素富集C2 F6的方法。富集的乙醇样品使用最近开发的HPLC法进行测量。基于计算值和测量值之间的差异，我们量化了在脱水、脱水和离子源电离过程中同位素体被打乱的程度。ResultsThe测量的13 C13 C值比13 C-13 C乙醇的量预期的低约20%。离子源中的电势扰乱估计为0.5- 2%，这低于观察到的同位素重排。结论对于典型的天然样品分析，离子源中的干扰作用仅能使样品中13 C13 C值的变化小于0.04‰，低于目前的分析精度（±0.07‰）。因此，所观察到的同位素重排可能发生在乙烯的氢化过程中，通过乙烯的同位素体的混乱，但不是在质谱仪的离子源或乙醇的脱水过程中，由于少量的C1和C3+分子。由此得到了经验传递函数λ 13 C13 CCSC = λ × λ 13 C13 C，对乙醇/乙烯和乙烷的α值分别为1.25 ± 0.01和1.00。使用经验传递函数，开发的方法可以提供实际的差异，在实际的传输值。
RationaleThe13C‐13C isotopologues of C2molecules have recently been measured using a fluorination method. The C2compound is first fluorinated into hexafluoroethane (C2F6), and its13C‐isotopologues are subsequently measured using a conventional isotope ratio mass spectrometer. Here, we present an approach for standardizing the fluorination method on an absolute reference scale by using isotopically enriched C2F6.MethodsWe prepared physical mixtures of13C‐13C‐labeled ethanol and natural ethanol. The enriched ethanol samples were measured using the recently developed fluorination method. Based on the difference between the calculated and measured ∆13C13C values, we quantified the extent to which isotopologues were scrambled during dehydration, fluorination, and ionization in the ion source.ResultsThe measured ∆13C13C value was approximately 20% lower than that expected from the amount of13C‐13C ethanol. The potential scrambling in the ion source was estimated to be 0.5–2%, which is lower than the observed isotopic reordering. Therefore, isotopic reordering may have occurred during either dehydration or fluorination.ConclusionsFor typical analysis of natural samples, scrambling in the ion source can only change the ∆13C13C value by less than 0.04‰, which is lower than the current analytical precision (±0.07‰). Therefore, the observed isotopic reordering may have occurred during the fluorination of ethene through the scrambling of isotopologues of ethene but not in the ion source of the mass spectrometer or during the dehydration of ethanol, given the small amount of C1and C3+molecules. Thus, we obtained the empirical transfer function ∆13C13CCSC= λ × ∆13C13C with avalue of 1.25 ± 0.01 for ethanol/ethene and 1.00 for ethane. Using the empirical transfer function, the developed fluorination method can provide actual differences in ∆ values.