Capture and Preservation of Single Aerosol Particles Through an Aerosol-Into-Emulsion Transition System

YI-BO ZHAO, Li Li, Bernard Olson, Christopher J. Hogan, University of Minnesota

     Abstract Number: 9
     Working Group: Instrumentation and Methods

Abstract
Analyses of single aerosol particles are commonly performed in a real-time and complex manner (e.g., optical tweezers or aerosol mass spectrometers), as there is a lack of capture and long-term storage methods preserving the chemical constituents of individual aerosol particles. We propose and demonstrate an aerosol-into-emulsion transition (AIET) approach to capture aerosol particles separately and preserve them for further analysis. Specifically, we develop an AIET system consisting of a temperature-controlled particle growth tube with water as the working fluid and a multi-nozzle impactor. The growth tube is based on the same principles as water condensation particle counters and growth collectors; aerosol particles grow several micrometers in diameter through water condensation. Subsequently, they are captured individually in a mineral oil/dodecane mixture with SPAN 80 as water-in-oil emulsions for long-term storage. We find that the ability to collect droplets and maintain them as individual droplets in an emulsion is strongly sensitive to the physical properties (viscosity, surface tension) of the collection oil. The AIET approach has been demonstrated with monodisperse fluorescent particles and in the collection of ambient aerosol particles. We envision that this new concept will enable greater choice in characterization techniques for single aerosol particles.