Emission Characteristics of Evaporative Intermediate-Volatility Organic Compounds from In-Use Gasoline Vehicles

The evaporation of intermediate-volatility organic compounds (IVOCs) from vehicle emissions substantially contributes to secondary organic aerosol (SOA) and ozone (O₃) formation. However, the limited characterization of evaporative IVOCs from in-use vehicles leads to uncertainties in assessing their atmospheric impact. Herein, aided by two-dimensional gas chromatography-mass spectrometry and flame ionization detectors (2D-GC-MS/FID), the highly resolved composition of IVOCs from in-use light-duty gasoline vehicles (LDGVs) are comprehensively characterized, revealing that the proportion of unresolved complex mixtures (UCMs) significantly decreased to 2.6%. In addition to aliphatic and aromatic IVOCs, the volatility distribution of O/N/S/Si-containing-IVOCs was newly illustrated, revealing their enhanced potential for evaporation in the low-volatility range. Moreover, IVOCs increased considerably with rising temperature, exhibiting significant temperature-dependent characteristics, and functional relationships were first established. In addition, different fuels and testing conditions were demonstrated to affect evaporative IVOC emissions. Obtaining a comprehensive understanding of IVOC composition, volatility distribution, temperature dependence, and other influencing factors fills the research gap and facilitates a more accurate characterization of the environmental impacts of IVOCs.