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| Titel |
Aerosol quantification with the Aerodyne Aerosol Mass Spectrometer: detection limits and ionizer background effects |
| VerfasserIn |
F. Drewnick, S. S. Hings, M. R. Alfarra, A. S. H. Prévôt, S. Borrmann |
| 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 ; 2, no. 1 ; Nr. 2, no. 1 (2009-02-12), S.33-46 |
| Datensatznummer |
250000425
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| Publikation (Nr.) |
 copernicus.org/amt-2-33-2009.pdf |
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| Zusammenfassung |
| Systematic laboratory experiments were performed to investigate
quantification of various species with two versions of the Aerodyne Aerosol
Mass Spectrometer, a Quadrupole Aerosol Mass Spectrometer (Q-AMS) and a
compact Time-of-Flight Aerosol Mass Spectrometer (c-ToF-AMS). Here we
present a new method to continuously determine the detection limits of the
AMS analyzers during regular measurements, yielding detection limit (DL)
information under various measurement conditions. Minimum detection limits
range from 0.03 μg m−3 (nitrate, sulfate, and chloride) up to 0.5 μg m−3
(organics) for the Q-AMS. Those of the c-ToF-AMS are found
between 0.003 μg m−3 (nitrate, sulfate) and 0.03 μg m−3
(ammonium, organics). The DL values found for the c-ToF-AMS were ~10
times lower than those of the Q-AMS, mainly due to differences in ion duty
cycle. Effects causing an increase of the detection limits include long-term
instrument contamination, measurement of high aerosol mass concentrations
and short-term instrument history. The self-cleaning processes which reduce
the instrument background after measurement of large aerosol concentrations
as well as the influences of increased instrument background on mass
concentration measurements are discussed. Finally, improvement of detection
limits by extension of averaging time intervals, selected or reduced ion
monitoring, and variation of particle-to-background measurement ratio are
investigated. |
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