High-Time Resolution Determination of Ions in Matrix Challenged Ambient Air Samples Using the Ion Chromatography Based URG Ambient Ion Monitor

Russell W. Long (1), Matthew S. Landis (1), Christopher R. Fortune (2), Julie M. Stone (3)

(1) U.S. EPA, National Exposure Research Laboratory, Research Triangle Park, NC 27711 (2) Alion Science and Technology, Research Triangle Park, NC 27711 (3) URG Corporation, Chapel Hill, NC 27516

     Abstract Number: 122
     Last modified: April 19, 2010

Abstract
Research conducted by the United States Environmental Protection Agency (EPA) at its facility in Research Triangle Park, NC and during field intensive studies in Michigan, Alabama and Ohio has demonstrated the capability for the high-time resolution determination of ions in matrix challenged ambient air samples using instrumentation based on liquid diffusion denuder (LDD), inertial particle separation and ion chromatography (IC) technology. Ions in ambient air exist as both components of particulate matter (PM) and their gas phase precursors. Ambient PM ions include but are not limited to sulfate, itrate, nitrite, and ammonium. Gas phase precursors that can be detected as ion include sulfur dioxide, nitric and nitrous acid, and amonia. The URG Series 9000 Ambient Ion Monitor (AIM, URG Corporation, Chapel Hill, NC) an IC-based sampler was evaluated in a laboratory setting using simulated ambient particles and gases to monitor its performance, compare its response to other measurement methods under controlled conditions and to identify potential sampling and analysis interferences. The AIM was also operated during field intensive studies in Dearborn, MI, (July-August 2007); Birmingham, AL (April-May 2008, September-October 2008); and Cleveland, OH (July-August 2009, February 2010) during which results obtained from the LDD-IC based AIM were compared to results obtained from additional high and low time resolution methods for the determination of ions in the particulate/gaseous ambient air matrix. A detailed description of the AIM components and principle of operation will be presented in addition to select results from the laboratory and field evaluations.

DISCLAIMER
Although this work was reviewed by EPA and approved for presentation, it may not necessarily reflect official Agency policy.