AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Semi-continuous Online Measurements of Reactive Oxygen Species in the Particle and Gas Phase
LAURA KING, Vishal Verma, Rodney Weber, Georgia Institute of Technology
Abstract Number: 186 Working Group: Instrumentation and Methods
Abstract Reactive oxygen species (ROS) have been linked to oxidative stress and acute inflammatory responses in the lungs; however, due to limitations in current monitoring capabilities the concentrations, sources or links to other gas and aerosol components of particle-bound ROS are not well known. Traditional particulate filter assessments are also limited due to potential sampling artifacts, highlighting the need for a continuous or semi-continuous method for quantifying ROS concentrations.
Two analytically similar semi-continuous online instruments have been developed to measure ROS. The first instrument uses a mist chamber to alternately collect ROS as a total gas and particle sample, and as a gas fraction. The second instrument uses the particle into liquid sampler (PILS) to collect ROS in the particle phase alone. Each instrument uses 2’,7’ dichlorofluorescin (DCFH) premixed with peroxidase from horseradish (HRP), combined with an fraction of the liquid sample to determine ROS concentration using a continuous flow through cell and spectrometer. The mist chamber system operates on a 10.5 minute cycle, analyzing a 5 minute sample, while the PILS system analyzes collected particles on a near-continuous basis, on a 5 minute cycle. The analytical systems have limits of detection of 2 nmol H2O2/L.
Results from ambient measurements of total ROS, gaseous ROS and particle ROS at contrasting sites will be presented along with ROS phase correlations with other gas and particle phase air quality parameters.