A Field-Based Approach for Determining ATOFMS Instrument Sensitivities to Ammonium and Nitrate
Abstract
Aerosol time-of-flight mass spectrometry (ATOFMS) instruments measure the size and chemical composition of individual particles in real-time. ATOFMS chemical composition measurements are difficult to quantify, largely because the instrument sensitivities to different chemical species in mixed ambient aerosols are unknown. In this paper, we develop a field-based approach for determining ATOFMS instrument sensitivities to ammonium and nitrate in size-segregated atmospheric aerosols, using tandem ATOFMS-impactor sampling. ATOFMS measurements are compared with collocated impactor measurements taken at Riverside, CA, in September 1996, August 1997, and October 1997. This is the first comparison of ion signal intensities from a single-particle instrument with quantitative measurements of atmospheric aerosol chemical composition. The comparison reveals that ATOFMS instrument sensitivities to both NH_4^+ and NO_3^- decline with increasing particle aerodynamic diameter over a 0.32−1.8 μm calibration range. The stability of this particle size dependence is tested over the broad range of fine particle concentrations (PM_(1.8) = 17.6 ± 2.0−127.8 ± 1.8 μg m^(-3)), ambient temperatures (23−35 °C), and relative humidity conditions (21−69%), encountered during the field experiments. This paper describes a potentially generalizable methodology for increasing the temporal and size resolution of atmospheric aerosol chemical composition measurements, using tandem ATOFMS-impactor sampling.
Additional Information
© 2002 American Chemical Society. Received for review December 3, 2001. Revised manuscript received July 25, 2002. Accepted August 21, 2002. Financial support for this research was provided by the U.S. Environmental Protection Agency under agreement No. R826371-01-0 (California Institute of Technology), by the Coordinating Research Council, Inc. and the U.S. DOE Office of Heavy Vehicle Technologies through the National Renew able Energy Laboratory under CRC Project No. A-22 (California Institute of Technology), by the California Air Resources Board through contracts No. 95-305 and 96-307 (University of California, Riverside), and by the National Renewable Energy Laboratory through contract No. ACI-17075-01 (University of California, Riverside). Thanks are due to Richard Carlin, Keith Coffee, Tas Dienes, Markus Gälli, Eric Gard, Deborah Gross, Sergio Guazzotti, Don-Yuan Liu, Christopher Noble, Sylvia Pastor, Philip Silva, David Suess, and Jeffrey Whiteaker, for assistance with the ATOFMS data collection (University of California, Riverside), and to Lara Hughes, Robert Johnson, Michael Kleeman, Paul Mayo, and Lynn Salmon, for assistance with the impactor data collection (California Institute of Technology). Constructive criticism from Deborah Gross, Michael Kleeman, Denis Phares, Jeffrey Whiteaker, and three anonymous reviewers greatly enhanced the quality of this manuscript.Attached Files
Supplemental Material - es015823i-3_s1.pdf
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Additional details
- Eprint ID
- 67733
- DOI
- 10.1021/es015823i
- Resolver ID
- CaltechAUTHORS:20160607-122447755
- R826371-01-0
- Environmental Protection Agency (EPA)
- Coordinating Research Council
- CRC Project No. A-22
- Department of Energy (DOE)
- 95-305
- California Air Resources Board
- 96-307
- California Air Resources Board
- ACI-17075-01
- NSF
- Created
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2016-06-07Created from EPrint's datestamp field
- Updated
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2023-02-24Created from EPrint's last_modified field