Molecular-level organic aerosol composition and volatility using chemical ionization high resolution time-of-flight mass spectrometry
Authors
Jose-Luis Jimenez — University of Colorado
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Joel Thornton — University of Washington
Julia Wargo — University of Washington
Joel K Kimmel — Aerodyne Research, Inc./Tofwerk
Amber V. Ortega — University of Colorado, Boulder
Laxmi Narasimha Reddy Yatavelli — Desert Research Institute
Description
The sources and transformations of aerosol organic matter remain uncertain. Mapping the evolution of organic aerosol composition on a molecular level remains crucial to developing accurate source attribution and mechanisms of chemical processing required for constraining coupled chemistry-climate models. Towards this end, we have developed an instrument coupling soft chemical ionization with a high-resolution time-of-flight (TOF) mass spectrometer for molecular-level analysis of organic matter in both the gas and particle phases without a chromatographic separation. Laboratory studies indicate the prototype has a high sensitivity to carboxylic acids (~ picogram detection limits) with a mass resolution of >4000 and mass accuracy of ~ 20 ppm. Together with the fast spectrum acquisition rate provided by TOFMS (0–500 amu at >10 Hz), these characteristics provide the potential to constrain aerosol component vapor pressures as a function of elemental composition and molecular mass. We demonstrate instrument performance using select standards, output from a Potential Aerosol Mass chamber, and preliminary field measurements. Finally, we discuss the planned application of this instrument to chamber studies of the aerosol life cycle and field measurements as part of the DOE GVAX campaign.
