文獻(xiàn)名： Preparation and application of magnetic graphene oxide coated with a modified chitosan pH-sensitive hydrogel: an efficient biocompatible adsorbent for catechin 作者： Hassan Sereshti, Soheila Samadi, Shohreh Asgaria and Maryam Karimia Department of Chemistry, Faculty of Science, University of Tehran, P.O. Box 14155-64555, Tehran, Iran 摘要：In the present study, graft copolymerization of acrylic acid sodium salt (AAS) onto O-carboxymethyl chitosan (O-CMCs) produced a highly hydrophilic and pH-sensitive hydrogel polymer of O-CMCs-g-AAS with a porous surface morphology. The grafted chitosan copolymer was coated on magnetic graphene oxide (MGO) and characterized with TEM, SEM, and FT-IR techniques. The prepared nanocomposite, [O-CMCs-g-AAS]/MGO, was successfully used as an efficient and biocompatible adsorbent in magnetic solid phase extraction (MSPE) coupled with gas chromatography-mass spectrometry (GC-MS) for preconcentration and determination of catechin in tea beverages. The influence of the main parameters affecting the quality of the coating process was investigated and optimized using a response surface methodology. Under the optimum conditions, the adsorbent demonstrated a satisfactory adsorption capacity (27 mg g?1) for catechin and good linearity in the range of 0.0055 g mL?1 with a determination coefficient (R2) of 0.9987. The limit of detection (LOD) and limit of quantification (LOQ) were 0.001 and 0.003 g mL?1, respectively. The relative standard deviation (RSD) was 4.1% (n = 5, C = 0.5 g mL?1).