AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Examining Evolution of Biogenic Organic Aerosols Using a Theoretical Carbon Number Functionality Grid
JUDITH PERLINGER, Tanvir Khan, Bo Zhang, Hans P. Arp, Michigan Technological University
Abstract Number: 359 Working Group: Carbonaceous Aerosols in the Atmosphere
Abstract According to the Abraham solvation model, non-ionic intermolecular interactions in aerosols as in other condensed phases can be characterized according to non-specific interactions (van der Waals and cavity formation) and three types of specific interactions (dipolarity/polarizability, hydrogen bond donor, and hydrogen bond acceptor interactions). The magnitude of these interactions is altered as aerosols are transformed through oxidation in the atmosphere. Interaction of organic aerosol species with atmospheric water, which affects aerosol optical properties, cloud condensation nuclei activation, and removal by precipitation, is expected to increase as hydrogen bond donor-acceptor (HDA) character and ionization increase. Using this model, a retention index diagram of a hypothetical, multidimensional gas chromatographic (GCx2GC) analysis of a mixture of non-ionic biogenic precursors and oxidation products can be created and used to quantify changes in organic aerosol. In GCx2GC analysis, separation of complex mixtures is achieved by diverting the modulated effluent from a polar or non-polar primary column, which separates species according to non-specific and specific interactions, into two polar secondary columns having different stationary phases that provide further separation of species. In previous simulations it was shown that, when derivatization was employed, and using 50%-trifluoropropyl-methylpolysiloxane as primary column and secondary columns 90%-cyanopropyl polysilphenylene-siloxane and polyethylene glycol, none of which undergo HDA interaction, the primary column was able to separate species by carbon number, and the polar secondary columns provided additional separation according to functionality. Here, we examine use of ionic liquid stationary phases, which undergo HDA interactions and as such provide enhanced separation of underivatized compounds. Using a combination of published measurements and computational chemistry, we examine theoretical retention in GCx2GC, including ionic liquid stationary phases, for hypothetical, complex mixtures of biogenic precursors and oxidation products.