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Sampling Duration Dependence of Semi-Continuous Organic Carbon Measurements on Steady State Secondary Organic Aerosols

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Abstract:Semi-continuous organic carbon concentrations were measured through several experiments of statically generated secondary organic aerosol formed by hydrocarbon + NOx irradiations. Repeated, randomized measurements of these steady state aerosols reveal decreases in the observed concentration with increasing sampling time for a given sampling flow rate. More pronounced changes are observed when a gas phase denuder is not upstream of the semi-continuous instrument. Initial results indicate that longer sampling integrations times will minimize the influence of the apparent sampling artifacts. Furthermore, these experiments indicate that reported organic carbon concentrations collected using one set of sampling time/flow rate parameters may not be comparable to other sampling protocols, especially when protocols involve short duration sampling, or when integrations periods are most dissimilar. Extrapolation of these results to ambient measurements of organic carbon also suggests that comparison of concentrations measured via differing instrumental protocols may lead to results which are not directly comparable.

This work has been funded wholly or in part by the United States Environmental Protection Agency under Contract 68-D-00-206 to ManTech Environmental Technology, Inc. Although this work was reviewed by the EPA and approved for publication, it may not necessarily reflect official Agency policy.
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Citation:Offenberg, J., M. Lewandowski, T. E. Kleindienst, E. O. Edney, M. Jaoui, and E. W. Corse. Sampling Duration Dependence of Semi-Continuous Organic Carbon Measurements on Steady State Secondary Organic Aerosols. Presented at American Association for Aerosol Research 2004 Annual Conference, Atlanta, GA, October 4-8, 2004.
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Contact: Liz Hope - (919) 541-2785 or hope.elizabeth@epa.gov
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Division: Human Exposure & Atmospheric Sciences Division
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Branch: Process Modeling Research Branch
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Product Type: Abstrct/Oral
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Presented: 10/07/2004
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Bullet Item Science Version of PM Chemistry Model
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Last Updated on Monday, October 22, 2007
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