Chamber Validation of Passive Ammonia Samplers

Nina Gartman1, Lee Green1, Chris Lehmann1 and John Walker2

The NADP is evaluating several passive sampler types as part of its Ammonia Monitoring Network (AMoN) special study. Three different passive sampler types were tested concurrently in an environmental chamber: Radiello (Sigma-Aldrich), Ogawa (Ogawa & Company), and Adapted Lowcost Passive High Absorption (ALPHA, United Kingdom Centre for Ecology & Hydrology). All samplers were prepared at the NADP's Central Analytical Laboratory (CAL), and shipped together with a travel blank to the U.S. EPA's National Risk Management Research Laboratory in RTP. After exposure, samplers were returned to the CAL, where they were extracted and analyzed. The environmental testing chamber is a 0.035 m3 Teflon-lined Plexiglas enclosure, approximately 61 cm long by 30.5 cm wide by 19 cm high. Samplers are suspended from a grid on the chamber ceiling in a random configuration. Circulation fans are used to ensure well-mixed conditions. Test gases are supplied using standard gas cylinders with the concentrations verified using closed circuit FTIR or impingers. Empirical factors were calculated for each sampler type as the ratio of measured concentrations (calculated using the manufacturer's supplied method) to the standard gas concentration.

1National Atmospheric Deposition Program/Central Analytical Laboratory, Illinois State Water Survey, Institute of Natural Resource Sustainability, University of Illinois at Urbana-Champaign, 2204 Griffith Dr., Champaign, IL; 217-244-0869;
2U.S. EPA, National Risk Management Research Laboratory, Air Pollution Prevention and Control Division, Research Triangle Park (RTP), NC; 919-541-2288;