Airborne extractive electrospray mass spectrometry measurements of the chemical composition of organic aerosol

Pagonis, Demetrios; Campuzano-Jost, Pedro; Guo, Hongyu; Day, Douglas A.; Schueneman, Melinda K.; Brown, Wyatt L.; Nault, Benjamin A.; Stark, Harald; Siemens, Kyla; Laskin, Alex; Piel, Felix; Tomsche, Laura; Wisthaler, Armin; Coggon, Matthew M.; Gkatzelis, Georgios I.; Halliday, Hannah S.; Krechmer, Jordan E.; Moore, Richard H.; Thomson, David S.; Warneke, Carsten; Wiggins, Elizabeth B.; Jimenez, Jose L.

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-to-flight calibration variability of 60 % (1inline-formulaσ). 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 PTR-MS) 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 (inline-formulaR2=0.77). AMS levoglucosan-equivalent concentrations and EESI-MS levoglucosan showed a greater difference, with a regression slope of 1.36 (inline-formulaR2=0.96), likely indicating the contribution of other compounds to the AMS levoglucosan-equivalent measurement. The total EESI-MS signal showed correlation (inline-formulaR2=0.9) with total organic aerosol measured by AMS, and the EESI-MS bulk organicpage1546 aerosol sensitivity was 60 % of the sensitivity to levoglucosan standards.



Pagonis, Demetrios / Campuzano-Jost, Pedro / Guo, Hongyu / et al: Airborne extractive electrospray mass spectrometry measurements of the chemical composition of organic aerosol. 2021. Copernicus Publications.


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