Coupling Liquid Chromatography with Aerosol Mass Spectrometry to Enhance Chemically Resolved Aerosol Analysis

Abstract. We present a novel analytical method that links liquid chromatography with aerosol mass spectrometry (LC-AMS) to separate and chemically characterize soluble constituents in atmospheric samples. This method is demonstrated here using ion chromatography (IC) to resolve ionic species prior to AMS detection. As the IC effluent is analyzed by the AMS, quantifiable ion signals and reproducible mass spectra are obtained every second throughout the chromatographic run. These chromatographically resolved AMS data yield quantitative information and chemical fingerprints for distinct and partially overlapping chromatographic features. The method was evaluated using standard mixtures of inorganic anions and cations, as well as atmospherically significant organic compounds (e.g., levoglucosan and organic acids). The IC-AMS chromatograms exhibited stable background signals, which permitted reliable integration of peak regions for quantification of the AMS-derived ions. Isotopically labeled ammonium sulfate ((NH₄)₂³⁴SO₄) was used as an internal standard to account for variations in aerosol generation efficiency and AMS sensitivity. Low-volatility compounds, such as ammonium sulfate and sucrose, showed recoveries close to 100 %. Application to an ambient aerosol sample collected during a wildfire event demonstrated that LC-AMS offers improved chemical resolution that can better characterize aerosol sources, atmospheric processing, and climate- and health-relevant properties.