Characterization of organic matter in total suspended particles by thermodesorption and pyrolysis-gas chromatography-mass spectrometry.
The organic matter in tropospheric aerosol plays an important role in atmospheric physical and chemical processes. The bulk of organic matter, representing a significant proportion of the total suspended particulate (TSP) mass, is bound to polymeric material whose structure and properties are largely unknown. Here we used thermodesorption gas chromatography/mass spectrometry (Td-GC/MS) to study organic compounds of low molecular mass and pyrolysis gas chromatography/mass spectrometry (Py-GC/MS) to characterize the chemical structure of macromolecules in TSP samples collected in different seasons from different sites in Guangzhou. n-Alkanes, fatty acids and nitriles were the predominant compounds in the thermodesorption products, whereas aromatics, fatty acids, nitriles and n-alkanes/alkenes were the major compounds in the pyrolysates. The results indicated that aromatics were main units in macromolecules. The fatty acids and nitriles formed from carboxylic ammonium salts were detected in both thermodesorption products and pyrolysates at a certain concentration, indicating the importance of these compounds in TSP formation. The TSP source mainly determined the occurrence of compounds in samples from urban, suburban and forest sites, whereas the TSP source and formation process maybe controlled the seasonal variation in compounds detected. High levels of nitriles in summer samples from suburban and forest sites coincide with the release of ammonium from the land and of fatty acids from vegetation at these sites.
Zhao
Jinping
J
State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
Peng
Ping'an
P
Song
Jianzhong
J
Shexia
Ma
M
Sheng
Guoying
G
Fu
Jiamo
J
D005227:Fatty Acids / Q000032:analysis; D008401:Gas Chromatography-Mass Spectrometry; D006358:Hot Temperature; D017672:Nitrogen Compounds / Q000032:analysis; D009930:Organic Chemicals / Q000737:chemistry*; D017601:Oxygen Compounds / Q000032:analysis; D052638:Particulate Matter / Q000737:chemistry*; D012621:Seasons
D005227:Fatty Acids; D017672:Nitrogen Compounds; D009930:Organic Chemicals; D017601:Oxygen Compounds; D052638:Particulate Matter