Characterization of high molecular weight compounds in urban atmospheric particles

[摘要] The chemical nature of a large mass fraction of ambient organic aerosolparticles is not known. High molecular weight compounds (often namedhumic-like substances) have recently been detected by several authors andthese compounds seem to account for a significant fraction of the totalorganic aerosol mass. Due to the unknown chemical structure of thesecompounds quantification as well as a determination of their molecularweight is difficult. In this paper we investigate water soluble humic-likesubstances in ambient urban aerosol using size exclusion chromatography-UVspectroscopy and laser desorption/ionization mass spectrometry (LDI-MS).LDI-MS was used for the first time to investigate HULIS from atmosphericaerosols. A careful evaluation of the two method shows that both methodscomplement each other and that both are needed to learn more about themolecular weight distribution and the concentration of humic-likesubstances. An upper molecular weight limit of humic-like substances ofabout 700 Da and a concentration of 0.3-1.6 µg/m³ air can beestimated, corresponding to 9-30% of the total organic carbon for anurban background site.

[学科分类] 大气科学