Magnetic solid-phase extraction of pyrethroid insecticides from tea infusions using ionic liquid-modified magnetic...

A simple, sensitive, and reliable magnetic solid-phase extraction (SPE) method coupled with GC-MS/MS for the effective analysis of four pyrethroids from tea infusions was developed. A magnetic adsorbent, named ionic liquid-modified magnetic zeolitic imidazolate framework-8 (Fe₃O₄/ZIF-8/IL), was prepared by immobilizing an ionic liquid (IL) on the surface of Fe₃O₄/ZIF-8. The textures of Fe₃O₄/ZIF-8/IL were confirmed by material characterization, and the results suggested that the adsorbent possessed high magnetism (59.0 emu g^-1), an adequate Brunauer-Emmett-Teller (BET) surface area (104 m² g^-1), and a large pore volume (0.68 cm³ g^-1). To confirm the extraction performance of the prepared Fe₃O₄/ZIF-8/IL, several experimental conditions affecting the extraction efficiency were investigated. Under the optimum conditions, the limits of determination (LODs) for the four pyrethroids were in the range of 0.0065-0.1017 μg L^-1 (S/N = 3 : 1) with an intra-day relative standard deviation (RSD) of ≤9.70% and inter-day RSD of ≤11.95%. The linear ranges were 0.5-50 μg L^-1 for bifenthrin and 0.5-500 μg L^-1 for permethrin, cypermethrin, and flucythrinate, with determination coefficients higher than 0.999. Finally, the proposed technique was successfully applied for the determination of pyrethroids in real tea infusions. This work could be extended to other IL-modified metal-organic frameworks (MOFs) and to the development of different sample pretreatment techniques.