AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
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Quantification of OH Radicals Generated by Secondary Organic Aerosols with Fluorometric Assay and Electron Paramagnetic Resonance Spectrometry
JINLAI WEI, Ting Fang, Manabu Shiraiwa, University of California, Irvine
Abstract Number: 377 Working Group: Health-Related Aerosols
Abstract The adverse health effects of ambient particulate matter (PM) are linked to the oxidative potential, known as the capability to generate reactive oxygen species (ROS) in vivo. Secondary organic aerosols (SOA) account for a large fraction of ambient PM, but the mechanisms of SOA inducing ROS generation are not well understood. Hydroxyl radicals are of great concern among ROS due to their drastic effects on biological tissues and cell components. Various acellular techniques have been applied for the quantification of OH, among which the fluorometric assay is most widely used. Electron paramagnetic resonance (EPR) spectrometry coupled with a spin trapping technique has also been used for OH measurements, which also enables simultaneous detection of other radical species including superoxide and organic radicals. However, the applications of these techniques have not been compared in measuring OH, and their pros and cons have not been well discussed. In this study, we investigated the hydroxyl radical generation from Fenton reaction using both fluorometric assay and EPR with spin trapping. Despite the difference in OH concentrations measured by the two methods, the kinetic modeling revealed a good agreement in OH production rate. Our preliminary results show that it is necessary to couple kinetic modeling with experimental techniques when bridging different methods in ROS measurement to exclude the impacts of associated artifacts. We plan to further investigate the ROS activity of laboratory-generated SOA from biogenic, anthropogenic and indoor-relevant precursors, and their interactions with transition metals using both techniques combined with kinetic modeling.