AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
A New, Automated System for the Simultaneous Determination of Gaseous Ammonia and Particulate Ammonium
MICHAEL BATTAGLIA JR., Julian Paige, Justin Thaggard, Christopher Hennigan, University of Maryland, Baltimore County
Abstract Number: 44 Working Group: Instrumentation and Methods
Abstract A new method is presented for the automated, on-line measurement of gaseous ammonia and particulate ammonium. A mist chamber (MC) collects ammonia while a Particle-into-Liquid Sampler (PILS) simultaneously collects water-soluble aerosol components, including ammonium. The liquid extracts from the MC and the PILS undergo reaction according to a simplified Berthelot method, in which ammonium undergoes reaction and forms a compound easily detected by colorimetric analysis. The method, which is used extensively for the analysis of water samples, is applied to atmospheric measurements for the first time. On-line mixing and liquid handling is performed using syringe pumps, calibrated to deliver the mixed reagent/sample to a liquid waveguide capillary cell with a 50 cm path length at a precise reaction time for color evolution. Spectrophotometric analysis using a modular spectrometer was performed at 660 nm. The on-line system was tested and validated against an AiRRmonia gas-phase ammonia analyzer and Metrohm 850 IC in preparation for field deployment and integration into existing liquid-phase collection and analysis protocols. Benefits of this modular online system are operational simplicity relative to gas-phase analyzers and IC, lighter-weight and more portable for field deployment, less expense than IC and gas-phase analytic instruments (instrumentation and operation), higher time resolution, and high sensitivity at atmospheric concentration levels (demonstrated to > 0.001 a.u. sensitivity).