Hitzfeld Kristina L, Gehre Matthias, Richnow Hans-Hermann
a Department of Isotope Biogeochemistry , Helmholtz-Centre for Environmental Research - UFZ , Leipzig , Germany.
Isotopes Environ Health Stud. 2017 May;53(2):116-133. doi: 10.1080/10256016.2016.1215983. Epub 2016 Aug 16.
In this study conversion conditions for oxygen gas chromatography high temperature conversion (HTC) isotope ratio mass spectrometry (IRMS) are characterised using qualitative mass spectrometry (IonTrap). It is shown that physical and chemical properties of a given reactor design impact HTC and thus the ability to accurately measure oxygen isotope ratios. Commercially available and custom-built tube-in-tube reactors were used to elucidate (i) by-product formation (carbon dioxide, water, small organic molecules), (ii) 2nd sources of oxygen (leakage, metal oxides, ceramic material), and (iii) required reactor conditions (conditioning, reduction, stability). The suitability of the available HTC approach for compound-specific isotope analysis of oxygen in volatile organic molecules like methyl tert-butyl ether is assessed. Main problems impeding accurate analysis are non-quantitative HTC and significant carbon dioxide by-product formation. An evaluation strategy combining mass spectrometric analysis of HTC products and IRMS O/O monitoring for future method development is proposed.
在本研究中，使用定性质谱法（离子阱）对氧气气相色谱高温转换（HTC）同位素比率质谱法（IRMS）的转换条件进行了表征。结果表明，给定反应器设计的物理和化学性质会影响HTC，进而影响准确测量氧同位素比率的能力。使用市售和定制的套管式反应器来阐明（i）副产物形成（二氧化碳、水、小有机分子），（ii）氧的第二来源（泄漏、金属氧化物、陶瓷材料），以及（iii）所需的反应器条件（调节、还原、稳定性）。评估了现有HTC方法对挥发性有机分子（如甲基叔丁基醚）中氧的化合物特异性同位素分析的适用性。阻碍准确分析的主要问题是HTC的非定量性和大量二氧化碳副产物的形成。提出了一种结合HTC产物的质谱分析和IRMS O/O监测的评估策略，用于未来的方法开发。
