Articles | Volume 8, issue 12
https://doi.org/10.5194/amt-8-5315-2015
https://doi.org/10.5194/amt-8-5315-2015
Research article
 | 
21 Dec 2015
Research article |  | 21 Dec 2015

An analytical system for stable isotope analysis on carbon monoxide using continuous-flow isotope-ratio mass spectrometry

S. L. Pathirana, C. van der Veen, M. E. Popa, and T. Röckmann

Abstract. A fully automated system for the determination of δ13C and δ18O in atmospheric CO has been developed. CO is extracted from an air sample and converted into carbon dioxide (CO2) using the Schütze reagent. The isotopic composition is determined with an isotope-ratio mass spectrometer (IRMS) technique. The entire system is continuously flushed with high-purity helium (He), the carrier gas. The blank signal of the Schütze reagent is ~ 4 nmol mol−1, or 1–3 % of the typical sample size. The repeatability is 0.1 ‰ for δ13C and 0.2 ‰ for δ18O. The peak area allows for simultaneous determination of the mole fraction with an analytical repeatability of ~ 0.7 nmol mol−1 for 100 mL of ambient air (185.4 nmol mol−1 of CO). An automated single measurement is performed in only 18 min, and the achieved time efficiency (and small volume of sample air) allows for repetitive measurements practically.

Download
Short summary
CO is established as an important indirect greenhouse gas, as it is the major sink for the OH∙. We have developed a fully automated system for the determination of δ13C and δ18O in atmospheric CO. The blank signal of the Schütze reagent is 1-3 % of the typical sample size. The repeatability is 0.1 ‰ for δ13C and 0.2 ‰ for δ18O. The analytical repeatability for the mole fraction is ~0.7 nmol mol-1 for 100 mL of ambient air (185.4 nmol mol-1 of CO). A single measurement is performed in 18 min.