▎ 摘　　要

Size-controlled magnetite nanoparticles (Fe3O4) with 200-1000 nm were synthesized by co-precipitation method. Then Fe3O4@SiO2@G@PIL was synthesized and used as modified QuEChERS adsorbent for the determination of preservatives in vegetables. The size of about 200 nm of Fe3O4 in Fe3O4@SiO2@G@PIL was selected as optimum size to clean-up. It not only exerted the nanometer features of magnetic nanoparticles, but also displayed the large specific surface area of graphene (G) and the solvent effects of polymeric ionic liquids (PILs). Various experimental parameters have been investigated. Under the optimized conditions, a simple, rapid and effective method for the determination of 20 preservatives residues in vegetables was established by modified QuEChERS to gas chromatography/mass spectrometry (GC-MS) analysis. The good linearity with correlation coefficients (R-2) of 0.9972-0.9999 was obtained over the range of 0.02-2.00 mg/L for 20 preservatives. The detection limits of the proposed method for 20 preservatives ranged from 0.82 to 6.64 mu g/kg. The adsorbent was successfully applied for extraction and determination of preservatives in vegetable samples, which thus was time-saving with keeping good clean-up performance. (C) 2016 Elsevier B.V. All rights reserved.