AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
The Atmospheric Organic Aerosol Explored Through High Resolution Mass Spectrometry
YIYI WEI, Tingting Cao, Yehia Mechref, Jonathan Thompson, Texas Tech University
Abstract Number: 394 Working Group: Aerosol Chemistry
Abstract The complexity of the organic aerosol often frustrates attempts to completely characterize this material on a molecular level. The required chemical analysis necessitates the ability to separate and speciate a broad variety of organics (alcohols, aldehydes, furans, amines etc...) that are often present at < ng m$^(-3) levels. Recent advances in molecular mass spectrometry move this suite of techniques towards being an optimal analyzer. For instance, electrospray ionization (ESI) allow ionization of analytes with minimal fragmentation in the source, and high resolution mass analyzers can assign m / z values to within 5 ppm mass accuracy, which can allow unambigious assignment of molecular formula.
In this work, we have explored use of the Orbitrap high resolution mass analyzer to better understand the chemistry occuring during the ozonolysis of squalene within a 3.6 m$^3 FEP lined chamber. Secondary aerosol generated in the chamber was collected on a filter from 0 to 1300 squalene ozonolysis lifetimes and analyzed in positive ion mode after extraction with 50:50 water / acetonitrile (ACN) with 0.05% formic acid preent. We observed approx. 1000 peaks in the mass spectrum in the m / z range of 100 - 500 with the most dominant peaks at 163.038, 149.022, and 279.159 m / z units. These peaks correspond to molecular formulas C$_9H$_7O$_3, C$_8H$_5O$_3, and C$_(16)H$_(23)O$_4, respectively. In addition, results from ambient aerosol samples collected in Lubbock, TX will also be presented. The mass spectra of the water / ACN extracts of these samples exhibited over 1000 distinct peaks not present in the blank, illustrating the complexity of the organic aerosol - even in a region not heavily influenced by VOC emissions.