Preparation Of A Novel Ionic Liquid Based Solid Microextraction Fiber And Its Application To Determination Of Pyrethroids

Pyrethroids, as a class of chemical pesticide, are widely used to prevent a variety of pests and its insecticidal toxicity than previous pesticides as the organic phosphorus, organochlorine pesticides, carbamate increased by10to100times, had mainly used in fruits, vegetables and grain crops.At present, the detection methods of pyrethroids in our country is mainly by instrumental analysis.The preparation technology is mainly on the use of liquid-liquid extraction and solid phase extraction, followed by gas chromatography. The experiments were based on the use of a novel ionic liquid in SPME sample preparation technique to detect pyrethroid pesticide residues. A solid-phase microextraction (SPME) fiber chemically linked with ionic liquid (IL), coupled to gas chromatography technique for the simultaneous sampling and determination of pyrethroids has been established.A new ionic liquid,1-vinyl-3-hexadecylimidazolium hexafluorophosphate (ViHDIm+PF6-), was synthesized and used as SPME fiber material. The IL-linked fiber was applied to the determination of pyrethroids in vegetables by direct immersion extraction (DI-SPME), followed by gas chromatographic separation and electron capture detection. Important extraction parameters, including extraction temperature, extraction time, stirring rate, desorption temperature and time were carefully optimized. The extraction efficiency of the IL-linked fiber for selected pesticides was higher than that of commercial100nm polydimethyl siloxane (PDMS) fiber.Several experiments were carried out to evaluate the analytical characteristics of the established SPME-GC-ECD method under optimum conditions. The linearity was from0.1to100μg L-1for fenpropathrin, from0.25to100μg L-1for cypermethrin, deltamethrin and permethrin, and from0.5to100μg L-1for flucythrinate, fenvalerate and fluvalinate. The limits of detection for seven pyrethroids were between0.07and0.29μgL-1. Single fiber reproducibility, expressed as relative standard deviation (RSD), was between5.32%and11.12%, and fiber-fiber reproducibility was between7.41%and15.02%. The established SPME-GC-ECD was successfully applied to detect pyrethroids in vegetables, the recoveries of cabbage were between67.40%and94.01%, with LODs between0.21and0.49μg L-1, and the recoveries of cucumber were between69.94%and90.38%, with LODs between0.25and0.46μg L-1.