Design and Application of a Novel Mass Spectrometry Technique for the Analysis of Atmospheric Secondary Organic Aerosols

Secondary organic aerosols (SOA) represent a large fraction of atmospheric particulate matter that affects air quality, climate, and human health. To develop accurate predictive atmospheric models for regulatory emission control policies, a deeper understanding of the SOA formation mechanisms is urgent. Currently, the knowledge of SOA formation mechanisms is limited by the lack of the aerosol chemical composition data. Thermal Desorption Ion Drift Chemical Ionization Mass Spectrometry (TD-ID-CIMS) offers a robust analytical platform for the study of the chemical composition of SOA.

We have developed a novel TD-ID-CIMS platform for the analysis of SOA particles. Our instrument utilizes soft vaporization and ionization methods that preserve the integrity of the molecular structures of the components of SOA particles. We have constructed an improved collection element to study SOA particles with mean geometric diameters of 5-200 nm. Current experiments are underway to validate and calibrate the instrument using representative model organic and inorganic aerosols, including organic acids, sulfuric acid, and ammonium sulfate known as main components of secondary atmospheric aerosols. We have established the analytical limit of detection of the new instrument down to the picogram level. Additional experiments aim to analyze the chemical composition of SOA particles from laboratory chamber experiments with the new particle collection/evaporation element built in our laboratory coupled to the TD-ID-CIMS.

Our new collection element coupled to our TD-ID-CIMS instrument offers a sensitive, robust, and versatile platform that can potentially expand the current understanding of the dynamics and chemical composition of SOA particles in the atmosphere.