Effects of Particle Phase State on the Measurement of Sea Spray Aerosol Composition Using Extractive Electrospray Ionization Mass Spectrometry

SAMANTHA KRUSE, Paul Tumminello, Alexia Moore, Christopher Lee, Kimberly Prather, Jonathan Slade, University of California San Diego

     Abstract Number: 666
     Working Group: Instrumentation and Methods

Abstract
Extractive electrospray ionization time-of-flight mass spectrometry (EESI) is an online technique for the measurement of aerosol molecular composition, offering high time resolution and reduced sample collection times. In this work, we measure three biological marker compounds (glycerol, palmitic acid, and potassium ions) in sea spray aerosol (SSA) with EESI during a phytoplankton bloom. We show SSA composition changes based on the three marker compounds dependent on biological activity in the seawater. We also found that the EESI sensitivity is dependent on sample relative humidity independent of pressure variations and reagent ion intensity. To characterize this effect, we modeled the reagent ion’s diffusive path through the sample aerosol and demonstrate that it is highly dependent on particle viscosity, which is modulated by relative humidity. These results align with recent studies which show that EESI sensitivity can be dependent on particle size and mixing state. These dependencies are also demonstrated in the results, where there is a higher sensitivity for compounds found at the particle surface. This work emphasizes the importance of particle phase state for the accurate measurement and quantification of aerosol composition using EESI.