Radiocarbon and Stable Carbon Isotope Ratio Analysis of CO, CO ₂ , and CH ₄ in Synthetic Air Mixtures with Environmental Applications

We developed a robust vacuum system for separating CH4, CO, and CO2 from laboratory-prepared and natural gaseous samples for radiocarbon (14C) and stable carbon isotope ratio (δ13C) analyses. The system is unique in its ability to isolate all three gases from a single sample without cross-contamination. While CH4 and CO2 are major greenhouse gases, atmospheric CO is a toxic air pollutant primarily emitted from incomplete combustion processes. As these species have different sources, tracing of individual gases needs efficient separation methods for δ13C- and 14C-based source identifications. The developed system achieves extraction efficiencies of ∼95-100% for all three gases, with negligible background contribution to the isotopic ratios and no detectable intermixing. System performance is demonstrated using synthetic air mixtures with controlled gas concentrations, as well as natural air samples collected from diverse environmental settings. The results confirm that the system is well suited for high-precision δ13C and 14C measurements of CO2, CH4, and CO in complex air matrices.