An Analytical System for Determining 17O in CO2 Using Continuous Flow-Isotope Ratio MS

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• 作者：Shinsuke Kawagucci ; Urumu Tsunogai ; Shingo Kudo ; Fumiko Nakagawa ; Hideyuki Honda ; Shuji Aoki ; Takakiyo Nakazawa ; and Toshitaka Gamo
• 刊名：Analytical Chemistry
• 出版年：2005
• 出版时间：July 15, 2005
• 年：2005
• 卷：77
• 期：14
• 页码：4509 - 4514
• 全文大小：348K
• 年卷期：v.77,no.14(July 15, 2005)
• ISSN：1520-6882

文摘

We developed a simple measurement system for ¹⁷O innanomole quantities of CO₂ using continuous flow isotoperatio mass spectrometry (CF-IRMS). The analytical systemconsisted of a sample injection system, a helium-purgedCO₂ purification line, a capillary GC, a combustion unit,and CF-IRMS. A unique feature of the system is that weuse molecular CO₂ to determine the isotopic compositionsincluding ¹⁷O. The ¹⁷O of CO₂ in a sample is calculatedfrom the mass ratios of both 45/44 and 46/44 of twodifferent kinds of CO₂, which have been purified quantitatively from different aliquots of a sample. While onealiquot (rCO₂) flows into IRMS directly, the other (eCO₂)flows through a CuO unit (900 C) prior to injection intoIRMS, to exchange oxygen atoms in the sample CO₂molecules with those in CuO for which we can assume¹⁷O = 0. In our system, we introduce both rCO₂ andeCO₂ alternately to IRMS repeatedly by using an automaticmultianalytical system to improve analytical precisionstatistically. The standard deviation of 0.35” for ¹⁷Ocan be realized using as little as 8.7 nmol CO₂ in a ~3-hanalysis. Based on this system, we have quantified ¹⁷Oin the stratospheric CO₂ over Japan.