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| Titel |
Online derivatization for hourly measurements of gas- and particle-phase semi-volatile oxygenated organic compounds by thermal desorption aerosol gas chromatography (SV-TAG) |
| VerfasserIn |
G. Isaacman, N. M. Kreisberg, L. D. Yee, D. R. Worton, A. W. H. Chan, J. A. Moss, S. V. Hering, A. H. Goldstein |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 7, no. 12 ; Nr. 7, no. 12 (2014-12-12), S.4417-4429 |
| Datensatznummer |
250115993
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| Publikation (Nr.) |
 copernicus.org/amt-7-4417-2014.pdf |
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| Zusammenfassung |
| Laboratory oxidation studies have identified a large number of oxygenated
organic compounds that can be used as tracers to understand sources and
oxidation chemistry of atmospheric particulate matter. Quantification of
these compounds in ambient environments has traditionally relied on low-time-resolution
collection of filter samples followed by offline sample
treatment with a derivatizing agent to allow analysis by gas chromatography
of otherwise non-elutable organic chemicals with hydroxyl groups. We present
here an automated in situ instrument for the measurement of highly polar
organic semi-volatile and low-volatility compounds in both the gas- and
particle-phase with hourly quantification of mass concentrations and
gas–particle partitioning. The dual-cell semi-volatile thermal desorption
aerosol gas chromatograph (SV-TAG) with derivatization collects
particle-only and combined particle-plus-vapor samples on two parallel
sampling cells that are analyzed in series by thermal desorption into helium
saturated with derivatizing agent. Introduction of MSTFA
(N-methyl-N-(trimethylsilyl)trifluoroacetamide), a silylating
agent, yields complete derivatization of all tested compounds, including
alkanoic acids, polyols, diacids, sugars, and multifunctional compounds. In
laboratory tests, derivatization is found to be highly reproducible
(< 3% variability). During field deployment, a regularly injected
internal standard is used to correct for variability in detector response,
consumption of the derivatization agent, desorption efficiency, and transfer losses.
Error in quantification from instrument fluctuations is found to be less
than 10% for hydrocarbons and less than 15% for all oxygenates for
which a functionally similar internal standard is available, with an
uncertainty of 20–25% in measurements of particle fraction. After
internal standard corrections, calibration curves are found to be linear for
all compounds over the span of 1 month, with comparable response on both of
the parallel sampling cells. |
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