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

Pagonis, D., P. 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. L. Jimenez (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