AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
Laboratory Evaluation of Organic Aerosol Chemical Composition and Partitioning Measurements Obtained from High-Resolution Mass Spectrometers with Different Soft Ionization Schemes
MANJULA CANAGARATNA, Jordan Krechmer, Melissa Morris, Andrew Lambe, Francesca Majluf, Harald Stark, Kaspar Daellenbach, Megan Claflin, Archit Mehra, Chenyang Bi, Brian Lerner, Felipe Lopez-Hilfiker, Gabriel Isaacman-VanWertz, John Jayne, Douglas Worsnop, Aerodyne Research, Inc.
Abstract Number: 566 Working Group: Instrumentation and Methods
Abstract Atmospheric organic aerosols remain an important topic of study because of their impacts on human health and climate. Historically, our community has lacked aerosol measurement techniques that can measure a high mass fraction of organic aerosols with high chemical resolution as well as high time resolution. Recently several techniques that combine soft-ionization with high-resolution mass spectrometry have been developed to address this need. Here, we utilize several of these soft-ionization techniques simultaneously in the laboratory to study SOA formed from anthropogenic precursors such as trimethylbenzene and catechol. The goals of this work are to combine these techniques to obtain a more complete characterization of the laboratory SOA and to compare and contrast the speciation capabilities of the various measurement methods. For this study we utilized a Filter Inlet for Gases and AEROsols coupled to a chemical-ionization mass spectrometer (FIGAERO-CIMS), a Vocus Inlet for Aerosols (VIA), and an extractive electrospray ionization inlet (EESI). We examine the influence of thermal decomposition, chemical fragmentation, and ionization selectivity on FIGAERO-CIMS, VIA and EESI-MS measurements. Additional volatility information obtained from the FIGAERO thermograms is also assessed. Overall, while each instrument observed many signals common with other instruments, instrument-specific biases were observed. The I-FIGAERO was biased towards more oxidized aerosol constituents, whereas the EESI-TOF treated more and less-oxidized aerosol constituents equally. Off-line measurements with gas chromatography (GC) and ion mobility spectrometry mass spectrometry (IMS-MS) are also utilized to obtain increased molecular-level identification obtained via isobaric and isomeric separation.