By: Lindsay Yee
Molecular composition of organic aerosols in urban and marine atmosphere: A comparison study using FIGAERO-I-CIMS, ESI-FT-ICR MS, and GC × GC-EI-ToF-MS
Authors of the Manuscript Featured: Xudong Xin, Yongyi Zhao, Yibei Wan, Honghai Zhang & Huan Yu
Aerosol Science and Technology, 58:10, 1142-1156, DOI: 10.1080/02786826.2024.2377394
This study compares the chemical composition of ambient organic aerosols (OA) in marine and urban environments using three different methods employing mass spectrometry: Electrospray Ionization-Fourier-Transform Ion Cyclotron Resonance Mass Spectrometry (ESI-FT-ICR MS), Filter Inlet for Gases and Aerosol-Iodide-Chemical Ionization Mass Spectrometry (FIGAERO-I-CIMS), and Two-dimensional Gas Chromatograph-Electron Ionization-Mass Spectrometry (GC x GC-EI-ToF-MS). This study finds that these techniques are complementary on the basis that each are sensitive to different types of compounds. For example, ESI(-)-FT-ICR MS and ESI(+)-FT-ICR MS were respectively sensitive to CHOS/CHONS and CHON species. FIGAERO-I-CIMS is typically used for detecting organic compounds with high acidity or polarity. In this study it was particularly sensitive to CHO compounds with C4–10 and O3–6, while CHO compounds measured with ESI-FT-ICR-MS tended to be C≥7 and O5-10. Due to the high resolution of FT-ICR-MS (550,000 at m/z = 300), ESI-FT-ICR-MS resulted in detection of 490-3491 formulae in negative mode and 213-4004 formulae in positive mode analyses of samples. In contrast, FIGAERO-I-CIMS had a resolving power of ~6000, leading to detection of 74-710 formulae for samples analyzed. Depending on the sample, roughly 50-85% of either FIGAER0-CIMS or ESI-FT-ICR MS determined chemical formulae were unique from the other method. GCxGC-EI-ToF-MS additionally detected organonitrates, carbonyls, alkanes, oxy-PAHs, and amides.
By combining the chemical characterization from all these techniques, urban aerosols were found to have greater number of CHON compounds than marine aerosols, and organonitrates were more common than reduced-nitrogen compounds regardless of environment. Continental sources impacting urban and marine aerosols led to enhancements of CHOS/CHONS, importantly organosulfates of biogenic origin. Aromatic-like organosulfates also tended to be less common compared to aliphatic organosulfates, and chlorine-containing aromatics tended to be more common in marine aerosols while chlorine-containing aliphatics tended to be more common in urban aerosols. Ultimately, the authors conclude that it is necessary to employ many MS methods to gain more complete chemical characterization of organic aerosols. This is also supported by Zhang et al. (2018), in which unique OA composition in a forested environment was also observed between FIGAERO-I-CIMS and a GC x GC-EI-ToF-MS configured differently from this study. As Xin et al., (2024) point out, ionization methods (chemical, electrospray, and electron impact), extraction methods (thermal desorption vs. solvent extraction), and separation technique (direct infusion vs. GC x GC) all contribute to the resulting chemical composition observed.
Further reading:
Xin, X., Zhao, Y., Wan, Y., Zhang, H. and Yu, H.: Molecular composition of organic aerosols in urban and marine atmosphere: A comparison study using FIGAERO-I-CIMS, ESI-FT-ICR MS, and GC × GC-EI-ToF-MS, Aerosol Sci. Technol., 58(10), 1142–1156, doi:10.1080/02786826.2024.2377394, 2024.
Additional reference:
XZhang, H., Yee, L. D., Lee, B. H., Curtis, M. P. M. P., Worton, D. R., Isaacman-VanWertz, G., Offenberg, J. H., Lewandowski, M., Kleindienst, T. E. T. E., Beaver, M. R., Holder, A. L., Lonneman, W. A., Docherty, K. S., Jaoui, M., Pye, H. O. T., Hu, W., Day, D. A. D. A., Campuzano-Jost, P., Jimenez, J. L., Guo, H., Weber, R. J., de Gouw, J. A., Koss, A. R., Edgerton, E. S., Brune, W., Mohr, C., Lopez-Hilfiker, F. D., Lutz, A., Kreisberg, N. M., Spielman, S. R., Hering, S. V., Wilson, K. R., Thornton, J. A. and Goldstein, A. H.: Monoterpenes are the largest source of summertime organic aerosol in the southeastern United States, Proc. Natl. Acad. Sci., 115(9), 2038–2043, doi:10.1073/pnas.1717513115, 2018.
This Issue’s Newsletter Committee:
Editor | Sarah Petters, University of California, Riverside
Senior Assistant Editor | Lindsay Yee, University of California, Berkeley
Junior Assistant Editor | Qian Zhang, UL Research Institute
Junior Assistant Editor | Robert Nishida, University of Waterloo