Application Of Novel Liquid-phase Microextraction Techniques In The Analysis Of Environmental Pollutants And Drugs

In the dertermination of environmental pollutants or drugs,Liquid-liquid extraction (LLE) is the classical method for its high recovery,stability and low cost,but its disadvantages are also inevitable,such as time-consuming,tedious,laborious and requires large amounts of toxic organic solvents,which have a great threaten on human health and environmental protection.Therefore,solvent-free extraction as a promising technique for sample preparation and pretreatment has become one of the most important research areas in modern analytical chemistry and attracted much attention recently.More recently,efforts have been placed on miniaturizing the LLE extraction procedure by greatly reducing the solvent to aqueous phase ratio,leading to the development of liquid-phase microextraction(LPME) methodology.LPME is based on the distribution effect of the analytes between a microdrop of organic solvent at the tip of a microsyringe needle and aqueous sample solution.In LPME,analytes were extracted from small volume of samples to only microlitre even nano-litre organic solvents.This technique belongs to the green analytical technique and is suitable to the development of micromation of modern analytical science.It combines extraction,preconcentration and sample introduction in one step,and proved to be a simple,fast and low-cost sample preparation method.Compared with solid-phase microextraction(SPME),LPME has a remarkable advantage that no special interface is needed when combining it with high-performance performance liquid chromatography(HPLC).Since the method was first introduced in 1996,LPME has been successfully applied for the application of environmental monitoring,food analysis,biological and medical analysis.Up to now,several different models of LPME have been developed,such as direct LPME,dynamic LPME,hollow fiber membrane LPME,headspace LPME, continuous-flow microextraction(CFME) and dispersive liquid-liquid microextraction (DLLME).When it comes to different sample solutions,different models of LPME can be used.Analytes with high volatilities can be extracted by headspace or direct LPME. for analytes with weak volatilities,direct LPM or DLLME can be used when the sample solution has clean background,otherwise hollow fiber membrane LPME can be used. In this study,new methods based on LPME combined with chromatography have been developed for the determination of environmental pollutants and drugs.