Extraction and Chromatography of targeted emission markers in atmospheric aerosols

Abstract: Atmospheric aerosols are a highly complex and dynamic mixture of solid particles, liquid deplots and gases. They travel across the continents and affect global climate and human health in various ways, often negatively. One important aspect of research in atmospheric aerosols is the investigation of emissions to the atmosphere from various sources. Emission markers are compounds unique to their sources of emission, hence, they act as fingerprints and are extensively used in source apportionment studies. It is highly challenging to sample, extract and quantify the compounds of interest, e.g. emission markers, from a complex mixture of thousands of organic and inorganic compounds, minerals and metals. A common bottleneck is the stringent requirements on the analytical methods, demanding high selectivity and low limits of detection. The work presented here focuses on the development of various extraction and chromatography methodsfollowed by mass spectrometry detection for the extraction, islation andquantitative anlaysis of targeted emission markers from complex aerosol samples.Development and optimization of various extraction and microextraction methods, optimization of different chromatography methods and mass spectrometry detection was motivated by the goals of higher selectivity, sensitivity, precision, accuracy, low limits of detection and low limits of quantification. Selection of greener solvents, reduced solvent use, shorter run times and eventually cheaper solutions were emphasised. The developed methods were compared with already existing methods in terms of 1) lower limits of detection, 2) reduced bias in analytical measurements and 3) greener alternatives. An interesting discovery on the formation of iron(III) complexes of 3-methyl-1,2,3-butane tricarboxylic acid, one of the emission markers for secondary biogenic emissions from monoterpenes,was also presented for the first time. The potential of the methods wasdemonstrated by their applications to aerosol samples as well as to solve societalproblems like early detection of smouldering fire using a unique emission marker.Finally, detailed description of hollow-fibre liquid-phase microextraction methodstudied for the extraction of 3-methyl-1,2,3-butane tricarboxylic acid waspresented along with the drawbacks of the method observed for the compound. It is expected that the research presented here will be a positive contribution in the estimation of emission markers and similar compounds from complex samples.