A Novel SPME Fiber Chemically Linked with 1-Vinyl-3-hexadecylimidazolium hexafluorophosphate Ionic Liquid Coupled with GC for the Simultaneous Determination of Pyrethroids in Vegetables

Abstract

A solid-phase microextraction (SPME) fiber chemically linked with ionic liquid (IL), coupled to gas chromatography–electron capture detector (GC–ECD) technique for the simultaneous sampling and determination of pyrethroids has been developed. A novel 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 seven pyrethroids in vegetables by direct immersion extraction, 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. Several experiments were carried out to evaluate the analytical characteristics of the SPME–GC–ECD method under optimum conditions. The limits of detection (LODs) for the seven pyrethroids were between 0.07 and 0.29 μg L−1. The linearity was from 0.1 to 100 μg L−1 for fenpropathrin, from 0.25 to 100 μg L−1 for cypermethrin, permethrin and deltamethrin, and from 0.5 to 100 μg L−1 for flucythrinate, fenvalerate and fluvalinate. Single fiber and fiber-to-fiber reproducibility, expressed as relative standard deviation, were less than 8.10 and 13.27 %, respectively. Compared with the commercial polydimethyl siloxane (PDMS) fiber, the extraction efficiency of the prepared IL-linked fiber for seven pyrethroids was about 20 % higher than that of PDMS fiber. The established SPME–GC–ECD was successfully applied in the detection of pyrethroids in cabbage and cucumber, with LODs of the seven pyrethroids between 0.21 and 0.49 μg kg−1 and recoveries of between 67.40 and 90.38 % in vegetables.