Sample Preparation of Organic Compounds in Environmental Analysis using Liquid Membrane Extraction

Sammanfattning: This thesis demonstrates the potential of the liquid membrane extraction technique as an alternative method for the analysis of trace ionisable organic compounds in the environment. Liquid membrane based extraction methods for the analysis of s-triazine herbicides and phenolic compounds were developed. Selectivity of the technique was demonstrated by extraction the above compounds in river water, river water spiked with high amounts of humic substances, wastewater and hydroponic nutrient solution for growing vegetables. Extracts from the various matrices analysed by reverse phase liquid chromatography with UV detection showed that they were free of interfering peaks. This therefore highlighted the liquid membrane technique as capable of selectively discriminating both polar and non-polar matrix components. Basic studies on the important parameters that influence the extraction and selectivity of the liquid membrane extraction technique were also performed. Studies showed that the first condition to achieving any extraction is analyte dissolution into the membrane. This is influenced by the polarity of both the analyte and membrane. With hydrophobic interactions as as the main mechanism of analyte dissolution into the membrane, analytes with octanol-water partition coefficients higher than 100 can be successively extracted in n-undecane or dihexyether as membrane liquids. In order to obtain high enrichment factors, complete trapping of the analytes in the acceptor is necessary. High enrichment factors can further be obtained within a relatively short extraction time by using high donor flow rate for compounds with octanol-water partition coefficients higher than 100 as the amount extracted per unit time increases for compounds with such polarity.