American Association for Aerosol Research - Abstract Submission

AAAR 36th Annual Conference
October 16 - October 20, 2017
Raleigh Convention Center
Raleigh, North Carolina, USA

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Droplet Assisted Inlet Ionization (DAII) for Online Molecular Analysis of Nanoparticles

MICHAEL J. APSOKARDU, Devan E. Kerecman, Yao Zhang, Andrew J. Horan, Murray Johnston, University of Delaware

     Abstract Number: 354
     Working Group: Instrumentation and Methods

Abstract
Molecular composition analysis is essential to our understanding of nanoparticle evolution and growth in the atmosphere, but typically can only be done offline, sacrificing time resolution. This creates a need for an analysis method capable of performing molecular analysis online. Droplet Assisted Inlet Ionization (DAII) has been developed for this purpose. In DAII, nanoparticles are first grown into aqueous microdroplets. The droplets subsequently pass through a heated capillary tube, where rapid vaporization results in the formation of molecular ions. Initial development of DAII has been done primarily with poly(propylene)-glycol (PPG) oligomers. DAII can detect PPG particles as small as 13nm in diameter, with sampled masses on the order of picograms. Additionally, particle and mass concentrations as low as 1000 particles/cm3 and 100 ng/m3 respectively can be measured, surpassing the necessary detection limits required to make ambient measurements. Further studies have been done with bovine serum albumin and angiotensin to demonstrate the capabilities of DAII to induce multiple charging on a single analyte, making DAII sensitive to both large and small molecules. Oligomers in secondary aerosol derived from cyclic siloxane oxidation have also been studied, with high resolution and good signal-to-noise in both positive and negative ion modes. These plus future studies of DAII will be presented.