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| Titel |
Chemical characterization of the main products formed through aqueous-phase photonitration of guaiacol |
| VerfasserIn |
Z. Kitanovski, A. Čusak, I. Grgić, M. Claeys |
| 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. 8 ; Nr. 7, no. 8 (2014-08-12), S.2457-2470 |
| Datensatznummer |
250115868
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| Publikation (Nr.) |
 copernicus.org/amt-7-2457-2014.pdf |
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| Zusammenfassung |
| Guaiacol (2-methoxyphenol) and its derivatives can be emitted into the
atmosphere by thermal degradation (i.e., burning) of wood lignins. Due to
its volatility, guaiacol is predominantly distributed atmospherically in the
gaseous phase. Recent studies have shown the importance of aqueous-phase
reactions in addition to the dominant gas-phase and heterogeneous reactions
of guaiacol, in the formation of secondary organic aerosol (SOA) in the
atmosphere. The main objectives of the present study were to chemically
characterize the main products of the aqueous-phase photonitration of
guaiacol and examine their possible presence in urban atmospheric aerosols.
The aqueous-phase reactions were carried out under simulated sunlight and in
the presence of hydrogen peroxide and nitrite. The formed guaiacol reaction
products were concentrated by solid-phase extraction and then purified with
semi-preparative high-performance liquid chromatography (HPLC). The
fractionated individual compounds were isolated as pure solids and further
analyzed with liquid-state proton, carbon-13 and two-dimensional nuclear
magnetic resonance (NMR) spectroscopy, and direct infusion negative ion
electrospray ionization tandem mass spectrometry ((−)ESI-MS/MS). The NMR
and product ion (MS2) spectra were used for unambiguous product
structure elucidation. The main products of guaiacol photonitration are
4-nitroguaiacol (4NG), 6-nitroguaiacol (6NG), and 4,6-dinitroguaiacol
(4,6DNG). Using the isolated compounds as standards, 4NG and 4,6DNG were
unambiguously identified in winter PM10 aerosols from the city of Ljubljana
(Slovenia) by means of HPLC/(−)ESI-MS/MS. Owing to the strong absorption
of ultraviolet and visible light, 4,6DNG could be an important constituent
of atmospheric "brown" carbon, especially in regions affected by biomass
burning. |
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