HR: 11:10h
AN: A72B-03    [Abstracts]
TI: Development of a New Calibration Method for an Ambient Ion Monitor Ion Chromatograph (AIM-IC)
AU: * Markovic, M
EM: mmarkovi@chem.utoronto.ca
AF: University of Toronto, 80 St. George Street, Toronto, ON M5S3H6, Canada
AU: VandenBoer, T
EM: tvandenb@chem.utoronto.ca
AF: University of Toronto, 80 St. George Street, Toronto, ON M5S3H6, Canada
AU: Murphy, J G
EM: jmurphy@chem.utoronto.ca
AF: University of Toronto, 80 St. George Street, Toronto, ON M5S3H6, Canada
AB: Fine atmospheric aerosols play an important role in the atmosphere as they alter the radiative balance of the Earth through direct and indirect climate effects, reduce visibility, participate in acid rain formation and affect human health. The motivation for chemically and temporally resolved measurements of fine aerosol composition has lead to the development of the Ambient Ion Monitor Ion Chromatograph (AIM-IC) system by Dionex/URG. This instrument is capable of simultaneously monitoring fine aerosols (<2.5μm) and associated precursor gases on a nearly continuous basis with a time resolution of 1 hour. The instrument utilizes a parallel-plate wet denuder with a constantly regenerated surface for collection of gases and a particle condensation chamber for the collection of aerosols. AIM-IC is capable of monitoring HCl(g), HONO(g), HNO₃(g), SO₂(g), NH₃(g), Cl^-, NO₂^-, NO₃^-, SO₄^2-, NH₄⁺ , and some water soluble organic acids and amines. Standard calibration of the AIM-IC is carried out by injecting a series of mixed standards directly onto the ion chromatographs, bypassing the sampling component of the instrument. This results in calculated detection limits on the order of 10-200 pptv for gases and 10-500 of ng/m³ for individual particle constituents when collecting at 3 L/min for 55 minutes. In this work, we present a new method for the calibration of the AIM-IC for both gas and particle collection that enables us to evaluate the entire system from size-selection to detection. This external calibration method is assessed for the gases HNO₃(g), SO₂(g), and NH₃(g), and for particles containing (NH₄)₂SO₄, NH₄NO₃, and Na₂SO₄. Quantitative collection of SO₂ is found to require careful optimization of the H₂O₂ concentration of the denuder liquid, while the replacement of a cyclone with an impactor improves the sampling efficiency of NH₃ and HNO₃.
DE: 0394 Instruments and techniques
SC: Atmospheric Sciences [A]
MN: 2009 Joint Assembly