Functional group analysis using tandem mass spectrometry :<br />Application to atmospheric organic aerosols

The particulate organic matter (POM) of atmospheric aerosols presents a chemical composition which is particularly complex. At best, only 20 % of the particulate mass can be identified by means of molecular speciation techniques. On the other hand, global analysis methods lead to a great simplification of the matrix and thus to a loss of information. The work carried out during this thesis aim to develop innovative and complementary methods of chemical analysis, enabling a better knowledge and a better comprehension of the organic fraction of atmospheric aerosols. Three functional group analytical methods using tandem mass spectrometry (MS/MS) have been developed, for the quantitative determination of the carboxylic (R-COOH), carbonyl (R-CO-R') and nitro (RNO2) functional groups. In the three cases, the precision of the measurements was estimated by calculating the variability obtained for the analysis of 25 reference mixtures constituted of 16 to 31 compounds according to the studied functional group, in different proportions from one mixture to another. The result of this statistical study shows an analytical error below 20 % for each of the three functional groups. The detection limits (approximately 0,005 mM) and the linearity range (0,01 - 0,5 mM) allowed the application of the developed methods to samples of secondary organic aerosols produced in simulation chamber, emission aerosols, and atmospheric aerosols. The results obtained are in accordance with literature and our present knowledge of the aerosols. Several lines of inquiry on the way of using the developed methods are finally presented, highlighting the relevance of this new approach in terms of source apportionment and aerosol ageing studies.