High-accuracy gas analysis via isotope dilution mass spectrometry: Carbon dioxide in air

Journal Article · Wed Nov 01 00:00:00 EST 1989 · Analytical Chemistry (Washington); (USA)

DOI:https://doi.org/10.1021/ac00196a019· OSTI ID:5952313

Verkouteren, R M; Dorko, W D ^[1]

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1. National Institute of Standards and Technology, Gaithersburg, MD (USA)

An absolute method, based on isotope dilution mass spectrometry, is described for the determination of atmospheric concentrations of carbon dioxide (CO{sub 2}) in dry air. In this study, the relative amounts of sample and spike gases are measured manometrically under temperature control before blending. The spike CO{sub 2} composition is approximately 0.1 atom % {sup 13}C while the oxygen isotopic composition is normal. Exhaustive assessment of potential error sources leads to accountability of observed imprecision and determination of accuracy confidence intervals (CI). The imprecision interval (95% CI) about the mean is smaller than {plus minus} 0.1% ({plus minus}0.4 {mu}mol/mol) while the accuracy interval (95% CI) is {plus minus}0.15% ({plus minus}0.52 {mu}mol/mol) for air having a CO{sub 2} concentration of about 350 {mu}mol/mol. Calculated concentrations of CO{sub 2} are statistically indistinguishable from those generated by gravimetry, an independent method of analysis. In this study, the major contributors to uncertainty and imprecision are the predetermination of the gas volume ratio and the measurement of the isotopic composition of the blended CO{sub 2}, respectively.

• OSTI ID: 5952313
• Journal Information: Analytical Chemistry (Washington); (USA), Vol. 61:21; ISSN 0003-2700
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
01 COAL, LIGNITE, AND PEAT
CARBON DIOXIDE
QUANTITATIVE CHEMICAL ANALYSIS
AIR QUALITY
GAS ANALYSIS
ISOTOPE DILUTION
MASS SPECTROSCOPY
SPECTRAL RESPONSE
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
CHEMICAL ANALYSIS
ENVIRONMENTAL QUALITY
ISOTOPE APPLICATIONS
OXIDES
OXYGEN COMPOUNDS
SPECTROSCOPY
TRACER TECHNIQUES
540120* - Environment
Atmospheric- Chemicals Monitoring & Transport- (1990-)
010900 - Coal
Lignite
& Peat- Environmental Aspects