Chemical characteristics of the assigned elemental formulas from the FT-ICR MS data of aerosol-derived organic matter simultaneously collected in Beijing, China and Gwangju, Korea in January 2018

In this study, ambient fine particles (PM2.5) were simultaneously collected in two urban cities in China and Korea (Beijing and Gwangju, respectively) in January 2018. Comprehensive compositional analysis of the organic matter (OM) samples, extracted using dichloromethane, was performed on a 15 Tesla Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer equipped with an atmospheric pressure photoionization (APPI) interface in positive ion mode. Analysis of the nonpolar and semipolar OM using APPI FT-ICR MS revealed that CHO and CHON accounted for more than 90% of the total intensity of the OM peaks. Higher proportions of CHON compounds were observed during PM2.5 events (i.e., days with abnormally high PM2.5 levels) at both sites than on regular or non-event days.