Stable Isotope Ratios Using Cavity Ring-Down Spectroscopy: Determination of 13C/12C for Carbon Dioxide in Human Breath
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- 作者：Eric R. Crosson ; Kenneth N. Ricci ; Bruce A. Richman ; Frank C. Chilese ; Thomas G. Owano ; Robert A. Provencal ; Michael W. Todd ; Jessica Glasser ; Alex A. Kachanov ; Barbara A. Paldus ; Thomas G. Spence ; an
- 刊名：Analytical Chemistry
- 出版年：2002
- 出版时间：May 1, 2002
- 年：2002
- 卷：74
- 期：9
- 页码：2003 - 2007
- 全文大小：77K
- 年卷期：v.74,no.9(May 1, 2002)
- ISSN：1520-6882
文摘
We have constructed a cavity ring-down spectrometeremploying a near-IR external cavity diode laser capableof measuring 13C/12C isotopic ratios in CO2 in humanbreath. The system, which has a demonstrated minimumdetectable absorption loss of 3.2 × 10-11 cm-1 Hz-1/2,determines the isotopic ratio of 13C16O16O/12C16O16O bymeasuring the intensities of rotationally resolved absorption features of each species. As in isotope ratio massspectrometry (IRMS), the isotopic ratio of a sample iscompared to that of a standard CO2 sample calibrated tothe Pee Dee Belemnite scale and reported as the sample's
13C value. Measurements of eight replicate CO2 samplesstandardized by IRMS and consisting of 5% CO2 in N2 atatmospheric pressure demonstrated a precision of 0.22”for the technique. 13C values were also obtained forbreath samples from individuals testing positive andnegative for the presence of Helicobacter pylori, theleading cause of peptic ulcers in humans. This studydemonstrates the ability of the instrument to obtain 13Cvalues in breath samples with sufficient precision to serveas a useful medical diagnostic.
13C value. Measurements of eight replicate CO2 samplesstandardized by IRMS and consisting of 5% CO2 in N2 atatmospheric pressure demonstrated a precision of 0.22”for the technique. 13C values were also obtained forbreath samples from individuals testing positive andnegative for the presence of Helicobacter pylori, theleading cause of peptic ulcers in humans. This studydemonstrates the ability of the instrument to obtain 13Cvalues in breath samples with sufficient precision to serveas a useful medical diagnostic.