Esler M B, Griffith D W, Wilson S R, Steele L P
Department of Chemistry, University of Wollongong, Australia.
Anal Chem. 2000 Jan 1;72(1):216-21. doi: 10.1021/ac990563x.
We report the development of a method of carbon stable isotope ratio analysis based on 1-cm-1 resolution Fourier transform infrared (FT-IR) spectroscopy, deployable in both laboratory and field applications. We demonstrate the determination of the 13C/12C ratio of CO2 (i.e., delta 13CO2) in air with an analytical precision of the order of +/- 0.1/1000 (i.e., +/- 0.01%). The FT-IR method relies on calibration using synthetically calculated absorbance spectra and a multivariate calibration algorithm. The method requires no sample preparation other than optional drying of the sample and may be applied directly to ambient air samples containing approximately 350 mumol mol-1 CO2 (molar mixing ratio). It may also be applied to samples more concentrated in CO2, such as human breath, approximately 5% CO2. We demonstrate the utility of the technique to the analysis of delta 13CO2 in air during an experimental field campaign and to the laboratory-based analysis of human breath. A similar method could also be used to determine the H/D ratio in atmospheric water vapor.
我们报告了一种基于1厘米-1分辨率傅里叶变换红外（FT-IR）光谱的碳稳定同位素比率分析方法的开发，该方法可用于实验室和现场应用。我们展示了对空气中二氧化碳的13C/12C比率（即δ13CO2）的测定，分析精度约为±0.1‰（即±0.01%）。FT-IR方法依赖于使用合成计算的吸收光谱和多元校准算法进行校准。该方法除了可选择对样品进行干燥外，无需样品制备，可直接应用于含有约350 μmol/mol-1二氧化碳（摩尔混合比）的环境空气样品。它也可应用于二氧化碳浓度更高的样品，如人体呼出气体，约含5%二氧化碳。我们展示了该技术在实验现场活动中对空气中δ13CO2分析以及在基于实验室的人体呼出气体分析中的实用性。类似的方法也可用于测定大气水汽中的H/D比率。
