Airborne extractive electrospray mass spectrometry measurements of the chemical...

Pagonis, D., Campuzano Jost, H. Guo, D. A. Day, M. Schueneman, W. Brown, B. Nault, H. Stark, K. Siemens, A. Laskin, F. Piel, L. Tomsche, A. Wisthaler, M. Coggon, G. Gkatzelis, H. Halliday, J. E. Krechmer, R. Moore, D. Thomson, C. Warneke, L. Wiggins, and J. Jimenez-Palacios (2021), Airborne extractive electrospray mass spectrometry measurements of the chemical composition of organic aerosol, Atmos. Meas. Tech., 14, 1545-1559, doi:10.5194/amt-14-1545-2021.

We deployed an extractive electrospray ionization time-of-flight mass spectrometer (EESI-MS) for airborne measurements of biomass burning aerosol during the Fire Influence on Regional to Global Environments and Air Quality (FIREX-AQ) study onboard the NASA DC-8 research aircraft. Through optimization of the electrospray working solution, active control of the electrospray region pressure, and precise control of electrospray capillary position, we achieved 1 Hz quantitative measurements of aerosol nitrocatechol and levoglucosan concentrations up to pressure altitudes of 7 km. The EESI-MS response to levoglucosan and nitrocatechol was calibrated for each flight, with flight-toflight calibration variability of 60 % (1σ ). Laboratory measurements showed no aerosol size dependence in EESI-MS sensitivity below particle geometric diameters of 400 nm, covering 82 % of accumulation-mode aerosol mass during FIREX-AQ. We also present a first in-field intercomparison of EESI-MS with a chemical analysis of aerosol online proton-transfer-reaction mass spectrometer (CHARON PTRMS) and a high-resolution Aerodyne aerosol mass spectrometer (AMS). EESI-MS and CHARON PTR-MS levoglucosan concentrations were well correlated, with a regression slope of 0.94 (R 2 = 0.77). AMS levoglucosan-equivalent concentrations and EESI-MS levoglucosan showed a greater difference, with a regression slope of 1.36 (R 2 = 0.96), likely indicating the contribution of other compounds to the AMS levoglucosan-equivalent measurement. The total EESIMS signal showed correlation (R 2 = 0.9) with total organic aerosol measured by AMS, and the EESI-MS bulk organic

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Research Program: 
Tropospheric Composition Program (TCP)
Funding Sources: 
NASA grants 80NSSC18K0630 and 80NSSC19K0124