American Association for Aerosol Research - Abstract Submission

AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA

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Identification of PM Components that Contribute to Oxidative Potential in the Dithiothreitol (DTT) Assay

JESSICA CHARRIER, Kennedy-Kiet Vu, Alam Hasson, Cort Anastasio, University of California, Davis

     Abstract Number: 575
     Working Group: Health Related Aerosols

Abstract
The rate of consumption of dithiothreitol (DTT) is increasingly used to measure the oxidative potential of particulate matter (PM), which has been linked to adverse health effects. It is important to identify which chemical components of PM cause DTT loss in order to better understand the results of this assay, inform in vivo health studies, and identify PM sources that may pose a higher health risk. In past work we have tested DTT loss from laboratory stocks of individual chemicals and found DTT activity from both soluble transition metals and quinones. We calculated that soluble metals should dominate the DTT response from ambient PM because their concentrations are larger than quinones. However, ambient PM is more complex than laboratory stock solutions, especially in regards to metal oxidation state and ligand binding. Extending findings from laboratory stocks to ambient PM is also complicated by the fact that past studies have not measured both soluble metals and quinones in the same PM samples. To better quantify the contributions of quinones and soluble metals to DTT loss from ambient PM, we are measuring DTT loss, and quinone and soluble metal concentrations, from PM2.5 samples collected in Claremont, CA and Fresno, CA. We will estimate the fraction of DTT loss from each quinone and transition metal using previously measured concentration response curves of pure compounds to identify which chemical species are most important for oxidant production and if these species account for the full oxidative potential of the PM. We will evaluate this approach by comparing the calculated DTT loss based on the chemical composition versus the measured DTT loss.