A simple and cost-effective sample preparation and storage method for stable isotope analysis of atmospheric CO for GasBench II/continuous flow isotope ratio mass spectrometry.

Rationale: The stable isotope compositions of atmospheric CO can provide useful insight into various geochemical processes and carbon cycles on Earth, which is critical for understanding of Earth's changing climate. Here, we present a simple and cost-effective analytical method for the collection and measurement of carbon and oxygen isotope compositions of atmospheric CO.

Methods: Air samples of ~150 mL were collected individually or collectively using our simple active air collection system and then extracted on a vacuum purification line to remove noncondensable gases and atmospheric water vapor.

Techniques for measuring carbon and oxygen isotope compositions of atmospheric CO via isotope ratio mass spectrometry.

Measuring the stable isotope compositions of atmospheric CO is common in earth and atmospheric sciences, and various analytical methods have been developed utilizing continuous-flow (CF) or dual-inlet (DI) isotope ratio mass spectrometry (IRMS). Air is typically collected via passive, manual, or automated collection methods and the volume of the air sample ranges from 10 to 300 mL for CF-IRMS to >1 L for DI-IRMS to yield a measurable amount of atmospheric CO gas. It has been determined that the integrity of vials and flasks for air sample storage can be compromised after 3 days of air collection for δ C values and within 10 hours for δ O values.