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Characterization of Polar Organosulfates in Secondary Organic Aerosol from the Green Leaf Volatile 3- Z -Hexenal

2014; American Chemical Society; Volume: 48; Issue: 21 Linguagem: Inglês

10.1021/es503226b

1520-5851

Mohammad Safi Shalamzari, Ariane Kahnt, Reinhilde Vermeylen, Tadeusz E. Kleindienst, Michael Lewandowski, Filip Cuyckens, Willy Maenhaut, Magda Claeys,

Atmospheric Ozone and Climate

Evidence is provided that the green leaf volatile 3-Z-hexenal serves as a precursor for biogenic secondary organic aerosol through the formation of polar organosulfates (OSs) with molecular weight (MW) 226. The MW 226 C6–OSs were chemically elucidated, along with structurally similar MW 212 C5–OSs, whose biogenic precursor is likely related to 3-Z-hexenal but still remains unknown. The MW 226 and 212 OSs have a substantial abundance in ambient fine aerosol from K-puszta, Hungary, which is comparable to that of the isoprene-related MW 216 OSs, known to be formed through sulfation of C5-epoxydiols, second-generation gas-phase photooxidation products of isoprene. Using detailed interpretation of negative-ion electrospray ionization mass spectral data, the MW 226 compounds are assigned to isomeric sulfate esters of 3,4-dihydroxyhex-5-enoic acid with the sulfate group located at the C-3 or C-4 position. Two MW 212 compounds present in ambient fine aerosol are attributed to isomeric sulfate esters of 2,3-dihydroxypent-4-enoic acid, of which two are sulfated at C-3 and one is sulfated at C-2. The formation of the MW 226 OSs is tentatively explained through photooxidation of 3-Z-hexenal in the gas phase, resulting in an alkoxy radical, followed by a rearrangement and subsequent sulfation of the epoxy group in the particle phase.