Kitamaki Yuko, Aoki Nobuyuki, Aoki Shinsuke, Ishida Hiroshi, Suzumura Masahiro
National Metrology Institute of Japan (NMIJ), National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki, 305-8563, Japan.
Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8567, Japan.
Anal Sci. 2023 Apr;39(4):619-623. doi: 10.1007/s44211-023-00279-8. Epub 2023 Feb 2.
Ambient air commonly contains carbon dioxide at concentrations greater than 400 µmol mol and methane at ~ 2000 nmol mol; non-methane hydrocarbons are also widespread in the atmosphere at much lower concentrations. For quantification of various carbon-containing compounds in typical analytical instrument, corresponding number of reference materials are required. Therefore, the development of a method that uses a single reference material applicable to air monitoring is desired. Here, we examined a post-column reaction system combined with a gas chromatograph equipped with a flame ionization detector (FID), which involves oxidation and reduction processes after separation. To determine various carbon-containing gases by post-column reaction gas chromatography with FID (GC-r-FID) using a single reference, it is necessary to confirm a good linearity of the response with carbon concentrations originating from various carbon-containing gases. When mixtures of carbon-containing gases at three different concentrations and the calibration curve of the FID response with the concentration converted into methane were used, a single linear calibration curve (correlation coefficient > 0.9999, 18 points) was obtained over four orders of magnitudes (to ~ 5000 µmol mol as methane). The applicability of GC-r-FID was confirmed by determining carbon-containing gases in air and gas seeped from the seafloor samples. Because the results were comparable to those obtained by conventional GC-FID and GC-thermal conductivity detector, typically GC-r-FID with a single reference gas should be suitable for air monitoring.
环境空气中通常含有浓度大于400 µmol/mol的二氧化碳和约2000 nmol/mol的甲烷；非甲烷碳氢化合物在大气中也广泛存在，但其浓度要低得多。对于在典型分析仪器中对各种含碳化合物进行定量分析，需要相应数量的标准物质。因此，人们期望开发一种使用适用于空气监测的单一标准物质的方法。在此，我们研究了一种柱后反应系统，该系统与配备火焰离子化检测器（FID）的气相色谱仪相结合，其中涉及分离后的氧化和还原过程。为了使用单一标准物质通过带FID的柱后反应气相色谱法（GC-r-FID）测定各种含碳气体，有必要确认来自各种含碳气体的碳浓度与响应之间具有良好的线性关系。当使用三种不同浓度的含碳气体混合物以及将浓度转换为甲烷后的FID响应校准曲线时，在四个数量级（以甲烷计至约5000 µmol/mol）范围内获得了一条单一的线性校准曲线（相关系数>0.9999，18个点）。通过测定空气中的含碳气体以及从海底样品中渗出的气体，证实了GC-r-FID的适用性。由于结果与通过传统GC-FID和GC-热导检测器获得的结果相当，通常使用单一标准气体的GC-r-FID应该适用于空气监测。
