Mass spectrometry-based <i>Aerosolomics</i>: a new approach to resolve sources, composition, and partitioning of secondary organic aerosol

Abstract. Particulate matter (PM) largely consists of secondary organic aerosol (SOA) that is formed via oxidation biogenic and anthropogenic volatile compounds (VOCs). Unambiguous identification SOA molecules their assignment to precursor vapors are challenges have so far only succeeded for a few marker compounds, which now well characterized (partly) available as authentic standards. In this work, we resolve the complex composition by means top-down approach based on newly created Aerosolomics database, fed non-target analysis results filter samples from flow reactor experiments. We investigated products five VOCs α-pinene, β-pinene, limonene, 3-carene, trans-caryophyllene four toluene, o-xylene, 1,2,4-trimethylbenzene, naphthalene. Using ultrahigh-performance liquid chromatography coupled high-resolution (Orbitrap) mass spectrometer, determine molecular formula 596 chromatographically separated exact isotopic pattern. utilize retention time fragmentation spectra basis unambiguous attribution parent VOCs. Based molecular-resolved application able assign roughly half total signal oxygenated hydrocarbons in ambient suburban PM2.5 one nine studied The database enabled us interpret appearance diurnal compound clusters different processes. Furthermore, performing hierarchical cluster (HCA) same set samples, identified depend sulfur dioxide mixing ratio temperature. This study demonstrates how tools (database HCA) applied PM can improve our understanding sources, formation pathways, temperature-driven partitioning compounds.