Studies And Application Of Liquid-phase Microextraction In Pesticide Residue Analysis

With the increase of human’s concern about environmental and food safety, the development of environmentally benign and more efficient sample pretreatment technique has been gaining popularity. Among newly developed sample pretreatment techniques, liquid-phase microextraction (LPME) was of great importance. The work in this paper was summarized as follows:The influence of dispersive solvent on dispersive liquid-phase microextraction in terms of droplet size of extraction solvent at disperse state, recovered sediment phase volumes and recoveries of different target analytes were investigated employing three organophosphorus pesticides as target analytes and two common types of extraction solvent namely organic solvent (chlorobenzene) and IL (1-Hexyl-3-methylimidazolium hexafluorophosphate,[C6MIM][PF6]) as extraction solvent. With the increase of dispersive solvent, the droplet size of chlorobenzene decreased from2313nm to219nm,[C6MIM][PF6] from3004nm to562nm. The recovered sediment phase volume of chlorobenzene decreased from15.0μL to3.8μL,[C6MIM][PF6] from18.9μL to9.5μL.DLLME based on ionic liquid (IL) was developed for determining multiple pyrethroid pesticide residue in both solid and liquid environmental samples. The main parameters in the extraction procedure were optimized. The recoveries were above89%, the limits of detection were between0.94and1.97μg/L.A temperature-controlled ultrasound-and vortex-assisted liquid-liquid microextraction as a fast and efficient approach for the extraction of nine organophosphorus pesticides in beverage samples were developed. The combination of ultrasonication and vortexing were used to assist the microextraction, and the use of a dispersion solvent was avcided. Temperature was controlled to obtain maximum amount of extraction solvent recovered. Several variables that could potentially affect the extraction efficiency were optimized. Under optimum conditions, the recoveries were above79.4%, the limits of detection were between0.01and0.05μg/L, the relative standard deviations were between4.5%and9.8%.Ultrasound-and vortex-assisted liquid-liquid microextraction using special vessel was developed for the analysis of organophosphorus pesticides in environmental water samples. Both heavy and light solvents are compatible with this technique. The relative standard deviations were between3.8%and7.9%, the limits of detection were between0.02and0.04μg/L.