Comparing the Reactivity of Aqueous Brown Carbon Precursors in Aqueous Solutions and Levitated Droplets

ERIN BOWEY, Prakriti Singh, James F. Davies, Paula K. Hudson, University of California, Riverside

     Abstract Number: 470
     Working Group: Aerosol Chemistry

Abstract
Aqueous phase reactions between aldehydes and small amino acids produce a wide array of products that contribute to the formation of brown carbon (BrC) aerosol. The reaction products and their chemical processing are highly variable and large uncertainties remain, especially with atmospheric aging over time. These reactions have been studied extensively in bulk aqueous solutions representative of cloud droplets, but the rapid liquid-vapor partitioning, enhanced surface adsorption and viscosity effects, and unique phase morphologies presented by droplets play important roles for their chemistry that are not reproducible in a bulk solution of similar composition. Furthermore, the influence of aerosol-phase processing following loss of water is not well understood. In this work, we leverage single particle levitation using a linear quadrupole electrodynamic balance (LQ-EDB) and mass spectrometry using an open port sampling interface (OPSI-MS) to compare the chemistry of glyoxal (GX) or methylglyoxal (MeGX) with glycine (Gly), in both bulk solution and levitated droplets. We compare the optical properties and composition for samples aged over a series of days, with varying initial compositions, with a focus on identifying the similarities and differences between aging in bulk solution versus aging in a droplet. These measurements will provide a more complete understanding of the formation and lifetime of aqueous BrC aerosol necessary to inform on their effects in the environment.