ANYL 122 |
| Recent changes in the earth's climate caused by global warming are a looming problem that will pose serious challenges for future generations. The accurate analysis of CO2 gas plays a critical role in this field of research. The WMO (World Meteorological Organization) has designated CO2 as a reference gas in analysis for non-dispersive IR (NDIR) to standardize international research. Carbon and Oxygen isotopes in the CO2 molecule absorb the distinctive resonant frequencies in IR spectrometers. However, widely used NDIR measurements use only the vibration band in the range of 2364±50 cm-1 for 12C16O2. If the isotopic abundances of CO2 samples deviate from standard CO2 gas, the NDIR measurement of CO2 will be inexact. In this study, isotopically different mixtures of CO2 were gravimetrically produced and used to study the effect of isotopic variations of CO2 in the NDIR measurements. The d13C values of two CO2 component gases, A and B, were measured to be -42 ‰ and -15 ‰ by an Isotope Ratio MS (Finigan Delta Plus). Using NDIR (Siemens, Ultramat 6E), the internal consistency of standard gas mixtures (A1 ~ A5), prepared with CO2 component gas (d13C = -42 ‰) was compared to mixtures (B1 ~ B2), prepared with d13C = -15 ‰ CO2 gas. The internal consistency of CO2 component gas (d13C = -42 ‰) was 0.050 mmol/mol with a 2 s uncertainty u = 0.012 mmol/mol. The difference between A group (A1 ~ A5) and B group (B1 ~ B2) was found to be 0.17 ± 0.01 mmol/mol, which within uncertainty is in agreement with the theoretically predicted value. |
|
General Papers
7:00 PM-9:00 PM, Sunday, 28 August 2005 Washington DC Convention Center -- Hall A, Poster
Division of Analytical Chemistry |