10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
A Semi-Automated System for Measuring the Reactive Oxygen Species (ROS) Catalyzed by Ambient Particulate Matter (PM) in a Dithiothreitol (DTT) Assay
HAORAN YU, Joseph Puthussery, Vishal Verma, University of Illinois Urbana-Champaign
Abstract Number: 520 Working Group: Aerosols and Health - Connecting the Dots
Abstract The oxidative potential of ambient particulate matter (PM), i.e. the ability to generate reactive oxygen species (ROS) in the presence of a biological reductant, has been investigated for a long period of time. In our previous study, we found that dithiothreitol (DTT) could be used to indicate the oxidative potential of PM by measuring both consumption rate of DTT and generation rate of •OH. Although, the measurement of DTT consumption has already been automated, •OH measurement, which is a labor-intensive process, still employs a manual protocol, limiting the number of samples that can be analyzed in a day. To overcome this problem, we are developing a system for analyzing the oxidative potential of PM liquid extracts based on the DTT assay in a semi-automated mode. This system uses DTNB to determine the concentration of DTT, and terephthalate (TPT) to capture the •OH generated from the oxidation of DTT. An automated Kloehn control pump system with sample injection valve is used to automate the protocol. A liquid wavelength capillary cell (LWCC) and a Horiba spectrofluorometer are used for quantifying the DTT and •OH concentration, respectively. The system will be calibrated with pure substances (9,10-phenanthraquinone, PQ and 5-Hydroxy-1,4-naphthoquinone, 5-H-1,4-NQ) as the positive controls, and will be tested for its performance with the real ambient PM samples collected from an urban site. The detection limit, accuracy and precision of the system will be evaluated. The seasonal variability in the oxidative potential of ambient PM measured by this system will also be presented. Finally, we anticipate that system can be coupled to a PM sampling device to monitor the oxidative potential of ambient PM in real-time.