Analysis of tracer molecules from organic aerosols - Application of liquid phase microextraction to aerosol analysis
Abstract: Airborne particulate matter is well known because of its adverse impacts on human health and its role in climate processes. In order to understand completely the role of aerosols in atmosphere, their chemical composition is of basic importance. Chemical analysis of aerosols involves broadly two steps, extraction step and detection/quantification of chemical constituents. Generally aerosols are extracted using classical techniques like Soxhlet extraction or using solvent extraction with help of ultrasonic agitation etc., which have many disadvantages. Liquid membrane extraction could offer some advantages and has never been used as a sample preparation step for aerosols. This dissertation addresses the use of both classical extraction methods and liquid membrane based extraction as a sample preparation steps for aerosols analysis. Common techniques that are used for this purpose are not environmentally green as they involve a lot of organic solvent, they are not efficient and selective enough and do not serve the purpose of trace level analysis as they do not give sufficiently high enrichment. We have shown that hollow fiber liquid phase microextraction (HF-LPME), which is environmentally green is applicable to aerosol samples. Both two-phase and three phase HF-LPME are very helpful in pre-concentration of analytes from aerosol. The dissertation summarises the results of our research for the last four years. Two-phase HF-LPME based analysis of polycyclic aromatic hydrocarbons from aerosols provided limits of detection (LOD) in the range of 2 – 180 pg m-3. Three-phase HF-LPME used for pre-concentration of pinic acid, pinonic acid and some ligin pyrolysis acids from aerosols gave LOD in the range of 10 – 50 pg m-3. Biomass burning tracers (levoglucosan etc.) were also analysed from aerosols and they were found to show high levels during winter.
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