Water soluble organic compounds (WSOC) in aerosol samples collected in the Ama-zon Basin in a period encompassing the middle/late dry season and the beginning of the wet season, were investigated by H NMR spectroscopy. HiVol filter samples (PM 2.5 and PM>2.5) and size-segregated samples from multistage impactor were subjected 5 to H NMR characterization. The H NMR methodology, recently developed for the anal-ysis of organic aerosol samples, has been improved exploiting chemical methylation of carboxylic groups with diazomethane, which allows the direct determination of the carboxylic acid content of WSOC. The content of carboxylic carbons for the different periods and sizes ranged from 12% to 20% of total measured carbon depending on 10 the season and aerosol size, with higher contents for the fine particles in the transition and wet periods with respect to the dry period. A comprehensive picture is presented of WSOC functional groups in aerosol samples representative of the biomass burning period, as well as of transition and semi-clean atmospheric conditions. A difference in
Functional group analysis by H NMR/chemical derivatization for the characterization of organic aerosol from the SMOCC field campaign.
2005
Abstract
Water soluble organic compounds (WSOC) in aerosol samples collected in the Ama-zon Basin in a period encompassing the middle/late dry season and the beginning of the wet season, were investigated by H NMR spectroscopy. HiVol filter samples (PM 2.5 and PM>2.5) and size-segregated samples from multistage impactor were subjected 5 to H NMR characterization. The H NMR methodology, recently developed for the anal-ysis of organic aerosol samples, has been improved exploiting chemical methylation of carboxylic groups with diazomethane, which allows the direct determination of the carboxylic acid content of WSOC. The content of carboxylic carbons for the different periods and sizes ranged from 12% to 20% of total measured carbon depending on 10 the season and aerosol size, with higher contents for the fine particles in the transition and wet periods with respect to the dry period. A comprehensive picture is presented of WSOC functional groups in aerosol samples representative of the biomass burning period, as well as of transition and semi-clean atmospheric conditions. A difference inI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
