Application Of Ionic Liquids In Sample Pretreatment Of Chromatography

In this work, the application of ionic liquid-based extraction techniques in sample pretreatment of different chromatographic methods was investigated. Novel ionic liquid-based liquid phase microextraction has been developed while the application of ionic liquids for the extraction of complex matrices and the combination of ionic liquid and accelerated solvent extraction method were also examined. The major content was composed of four chapters.Chapter one comprised a brief introduction of ionic liquid and its application in analytical chemistry and a comprehensive review of the application of ionic liquid extraction methods in sample pretreatment of chromatography and the ionic liquid extraction techniques consisted of liquid-liquid extraction, liquid phase microextraction, solid phase (micro)extraction, ionic liquid supported hollow fiber membrane microextraction and microwave assisted extraction.In chapter two, hydrophobic ionic liquid was used for the extraction of phenols and aromatic amines from water samples. On the basis of ionic liquid based liquid-liquid extraction, a novel liquid phase microextraction method termed ionic liquid based liquid-liquid dispersive microextraction, for the first time, was developed. Parameters that might affect the extraction efficiency such as extraction time, the concentration of added salt, the volume of ionic liquid and pH values of aqueous phase were examined. Experiments indicated that compared with liquid-liquid, ionic liquid based liquid-liquid dispersive microextraction was very rapid and only required a small amount of sample.In chapter three, ionic liquid was used for the extraction of complex matrices including chilli powder, chilli oil, food additive, meat products and glace fruit samples. The combination of ionic liquid micelles solution for the extraction of sulfonamides from meat products followed by anion-exchange chromatography was investigated and ionic liquid micelles solution was also used for the extraction of organic acids from glace fruit samples combined with accelerated solvent extraction. Experiments demonstrated that good recoveries and extraction efficiency could be obtained with one step ionic liquid extraction.In chapter four, the possibility of the combination of ionic liquid with gas chromatography has been examined. The analysis of organic compounds extracted into ionic liquid phase via thermal desorption and headspace gas chromatography was investigated. Experiments showed that headspace gas chromatography was a feasible alternative for the analysis of organic compounds extracted into ionic liquid. However, there were still some problems for the analysis of organic compounds extracted into ionic liquid with thermal desorption-gas chromatography.