AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
Epoxide Formation from Heterogeneous Oxidation of Polycyclic Aromatic Hydrocarbon with Gas-phase Ozone
SHOUMING ZHOU, Leo Yeung, Scott Mabury, Jonathan Abbatt, University of Toronto, Toronto, Canada
Abstract Number: 40 Working Group: Aerosol Chemistry
Abstract Polycyclic aromatic hydrocarbons (PAHs) are a class of ubiquitous air pollutants generated as by-products from incomplete combustion processes. PAHs can also be formed in indoor environments by meat cooking, candle burning and tobacco smoke. Due to their toxic effects on humans, PAHs and their biological/chemical degradation have received extensive studies. While several mechanisms for metabolic activation of PAHs have been proposed, bay-region diol-epoxide formation is believed to play an essential role in the toxicity of PAHs. Toxicological studies also show that the mono epoxides from biotic degradation of PAHs are mutagenic and cytotoxic. Studies on the chemical degradation of PAHs, on the other hand, have shown the formation of a series of oxygenated products, including phenols, quinones, carbonyls and carboxylic acids. To date only one study reported the formation of mono epoxide from oxidation of benzo[a]pyrene (BaP) with ozone.
In this presentation, we will show the experimental evidence of epoxide formation from heterogeneous oxidation of BaP with ozone. The epoxides were derivatized with N-acetylcysteine (NAC) and then analyzed by an LC-MS/MS. In addition to mono epoxide, diol epoxides were determined for the first time from BaP/O3 system. By assuming similar ionization efficiencies between the diol epoxides from the reaction and the standards, a diol epoxide yield is estimated to be as high as ~25%. Moreover, mono and diol epoxides were also observed when BaP was exposed to indoor air.