Recent Advances of Microextraction with Ionic Liquid as Friendly Acceptor Phase for Sample Preparation in Analytical Chemistry

Ionic liquid has been rapidly developed as an environment-friendly acceptor phase for microextraction and sample preparation in analytical chemistry in recent years. Present microextraction with ionic liquid mainly includes liquid phase microextraction, single drop liquid phase microextraction, solid phase microextraction, dispersive liquid phase microextraction and cold induced aggregation microextraction. In general, the microextraction with ionic liquid exhibits higher extraction efficiency and enrichment factor than that with organic solvent. Hydrophobic ionic liquids are difficult to fully mix with aqueous phase due to very high interfacial tension between the ionic liquid and water, a relatively long extraction time and manual stirring process were strongly required for improving extraction efficiency of the microextraction with ionic liquid. Recently, a novel microextraction technology termed as dispersive liquid phase microextraction was developed and applied rapidly, in which the ionic liquid was dispersed completely into the aqueous phase and the analytes will more easily migrate into the ionic liquid phase because of the much large contact area, its extraction time was shorten remarkably and whole extraction can be completed within several minutes. Moreover, the combinations of many modern analytical technologies with the ionic liquid microextraction were investigated and improved, special to gas chromatography and gas chromatography mass spectrometry. These have widely been applied to determination of ultra trace metal and organic compound in water or other samples. Up to now, the microextractions with ionic liquid have increasingly become one of most important method for samples preparation in analytical chemistry.