GC-MS ANALYSIS OF WATER-SOLUBLE ORGANICS IN ATMOSPHERIC AEROSOL AS ORGANIC TRACERS OF ATMOSPHERIC PROCESSES

Water-soluble organic compounds (WSOCs), mainly dicarboxylic acids and sugars, are animportant group of chemical tracers present in the atmosphere that can be primarily emitted by a multiplicity of sources -- including power plants, vehicular circulation, meat cooking operations and biomass burning -- or secondarily produced by photochemical atmosphere reactions fromboth biogenic and anthropogenic precursors. A multi-residue analytical methodology has been developed for the simultaneous GC-MS analysis of a wide range of WSOCs in atmospheric aerosol by optimizing the operating conditions of the silylation procedure -- i.e., reaction temperature and duration, reagent concentration. The optimized procedure provides the lowdetection limits (lower tha 2 ngm-3) and the good reproducibility (RSD%lower than 13%) required by environmental monitoring .The procedure was applied to quantify WSOCs in fine (PM2.5) and ultrafine (PM1) aerosol samples collected in a local area surrounding Bologna, Northen Italy, during separate month-long intensive summer and winter campaigns of Moniter project (Environment Agency of Emilia Romagna region). The obtained results show that in all samples, the most concentrated compound is levoglucosan, as the major by-product from biomass burning. The other abundant molecular tracers were: azelaic acid, marker of vegetation emission; adipic, hydroxy benzoic and phthalic acids, tracers of anthropogenic secondary aerosol; glucose and mycose, key molecular markers of soil resuspension; and arabinose, galactose and maltose, indicators of primary emissions from biogenic sources