Magnetic graphene coated inorganic-organic hybrid nanocomposite for enhanced preconcentration of selected pesticides in tomato and grape

The new magnetic graphene based hybrid silica N-[3-(trimethoxysilyl)propyllethylenediamine (MG@SiO2-TMSPED) nanocomposite was synthesized via sol-gel process, and used as an effective adsorbent in magnetic solid phase extraction (MSPE) of three selected pesticides followed by gas chromatography micro-electron capture detection (GC-mu ECD). The adsorbent was characterized using Fourier transform-infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET), Barrett-Joyner-Halenda (BJH), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive Xray spectroscopy (EDXS) techniques. The analytical validity of the developed method was evaluated under optimized conditions and the following figures of merit were obtained: linearity, 1-20 mu g kg(-1) with good determination coefficients (R-2 =0.995-0.999); limits of detection (LODs), 0.23-030 mu gkg(-1) (3 x SD/m, n = 3); and limits of quantitation (LOQ), 0.76-1.0 mu g kg(-1) (10 x SD/m, n = 3). The precision (RSD%) of the proposed MSPE method was studied based on intra-day (3.43-8.83%, n = 3) and inter-day (6.68-8.37%, n = 12) precisions. Finally, the adsorbent was applied to determination of pesticides in tomato and grape samples and good recoveries were obtained in the range from 82 to 113% (RSDs 5.1-8.1%, n = 3). (C) 2017 Elsevier B.V. All rights reserved.