Comparative Evaluation of Non-Polar and Polar Chromatographic Columns for Analyzing Oxygenated Intermediate-Volatility Organic Compounds in Air Samples by Thermal Desorption–GC/MS

Oxygenated intermediate-volatility organic compounds (OIVOCs) represent an important but poorly constrained class of secondary organic aerosol (SOA) precursors due to analytical challenges in their molecular-level characterization. In this study, we conducted a systematic comparison of a non-polar gas chromatography column (HP-5MS) and a polar column (DB-Heavy WAX) for the measurement of atmospheric OIVOCs using thermal desorption–gas chromatography–mass spectrometry (TD–GC/MS). A set of 48 representative oxygenated standards together with urban ambient air samples was analyzed to evaluate chromatographic separation, compound identification, and quantitative responses. The developed analytical method demonstrated excellent linearity (R2 > 0.90) and precision, with relative standard deviations (RSDs) typically below 10%. The polar WAX column provided improved chromatographic resolution and peak shapes for 39 oxygenated standards (e.g., ether alcohols, esters, diesters, and nitrogen-containing compounds) driven by strong intermolecular hydrogen bonding and dipole interactions, whereas the HP-5MS column showed stronger selectivity toward non-polar species such as long-chain siloxanes and branched alkanes. Application to urban ambient samples revealed that the WAX column increased the number of identifiable OIVOC species by 14.6% relative to the HP-5MS column. Furthermore, total OIVOC concentrations derived from the WAX column were 7% higher than those obtained using the HP-5MS column, while OIVOC-to-alkane ratios were 2–4 times greater. These differences demonstrate that chromatographic selectivity can influence the characterization of oxygenated compounds within the IVOC volatility range. The potential implications of these analytical differences were further illustrated through secondary organic aerosol formation potential (SOAFP) estimation, although the limited availability of experimental SOA yield data remains a major uncertainty. Overall, this study demonstrates that appropriate chromatographic method selection is essential for reducing analytical uncertainty and improving the molecular characterization of OIVOCs in complex environmental samples.