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| Titel |
Identification of humic-like substances (HULIS) in oxygenated organic aerosols using NMR and AMS factor analyses and liquid chromatographic techniques |
| VerfasserIn |
M. Paglione, A. Kiendler-Scharr, A. A. Mensah, E. Finessi, L. Giulianelli, S. Sandrini, M. C. Facchini, S. Fuzzi, P. Schlag, A. Piazzalunga, E. Tagliavini, J. S. Henzing, S. Decesari |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 14, no. 1 ; Nr. 14, no. 1 (2014-01-02), S.25-45 |
| Datensatznummer |
250118241
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| Publikation (Nr.) |
 copernicus.org/acp-14-25-2014.pdf |
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| Zusammenfassung |
| The atmospheric organic aerosol composition is characterized by a great
diversity of functional groups and chemical species, challenging simple
classification schemes. Traditional offline chemical methods identify
chemical classes based on the retention behaviour on chromatographic columns
and absorbing beds. Such an approach led to the isolation of complex mixtures
of compounds such as the humic-like substances (HULIS). More recently,
online aerosol mass spectrometry (AMS) was employed to identify chemical
classes by extracting fragmentation patterns from experimental data series
using statistical methods (factor analysis), providing simplified schemes for
the classification of oxygenated organic aerosols (OOAs) on the basis of the
distribution of oxygen-containing functionalities. The analysis of numerous
AMS data sets suggested the occurrence of very oxidized OOAs which were
postulated to correspond to HULIS. However, only a few efforts were made to
test the correspondence of the AMS classes of OOAs with the traditional
classifications from the offline methods. In this paper, we consider a case
study representative of polluted continental regional background
environments. We examine the AMS factors for OOAs identified by positive
matrix factorization (PMF) and compare them to chemical classes of water-soluble
organic carbon (WSOC) analysed offline on a set of filters collected in
parallel. WSOC fractionation was performed by means of factor analysis
applied to proton nuclear magnetic resonance (NMR)
spectroscopic data, and by applying an ion-exchange chromatographic method
for direct quantification of HULIS. Results show that the very oxidized
low-volatility OOAs from AMS correlate with the NMR factor showing HULIS
features and also with true "chromatographic" HULIS. On the other hand,
UV/VIS-absorbing polyacids (or HULIS {sensu stricto}) isolated on
ion-exchange beds were only a fraction of the AMS and NMR organic carbon
fractions showing functional groups attributable to highly substituted
carboxylic acids, suggesting that unspeciated low-molecular weight organic
acids contribute to HULIS in the broad sense. |
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