Technique for High-Precision Analysis of Triple Oxygen Isotope Ratios in Carbon Dioxide

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• 作者：Magdalena E. G. Hofmann ; Andreas Pack
• 刊名：Analytical Chemistry
• 出版年：2010
• 出版时间：June 1, 2010
• 年：2010
• 卷：82
• 期：11
• 页码：4357-4361
• 全文大小：147K
• 年卷期：v.82,no.11(June 1, 2010)
• ISSN：1520-6882

文摘

Since the discovery of mass-independent isotope effects in stratospheric and tropospheric gases, the analysis of triple oxygen isotope abundance in carbon dioxide gained in importance. However, precise triple oxygen isotope determination in carbon dioxide is a challenging task due to mass-interference of ¹⁷O and ¹³C variations. Here, we present a novel analytical technique that allows us to determine slight deviations of CO₂ from the terrestrial fractionation line [TFL]. Our approach is based on isotopic equilibration between CO₂ gas and CeO₂ powder at 685 °C and subsequent mass spectrometric analysis of ceria powder by infrared-laser fluorination. We found that β_CO2-CeO2, the exponent in the relation α^17/16 = (α^18/16)^β, amounts to 0.5240 ± 0.0011 at 685 °C. The oxygen isotope anomaly of CO₂ (Δ¹⁷O) can be determined for a single analysis of CeO₂ with a precision of ±0.05 ‰ (1σ). Our CO₂−CeO₂ equilibration procedure is performed with an excess of CO₂ so that one analysis of Δ¹⁷O on CO₂ requires at least 3.5 mmol of CO₂ gas. Our new technique allows accurate and precise determination of Δ¹⁷O in CO₂ and opens up a new field for investigating triple oxygen isotope abundance in various types of natural CO₂.