Amphiphilic block copolymer-grafted magnetic multi-walled carbon nanotubes as QuEChERS adsorbent for simultaneous determination of mycotoxins and pesticides in grains via liquid chromatography tandem mass spectrometry.

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An amphiphilic block copolymer consisting of poly(N-acryloyl-glucosamine) (PAGA) and poly(tert-butyl methacrylate) (PtBMA) was designed and grafted on magnetic multi-walled carbon nanotubes (Fe3O4MWCNTs). The resultant Fe3O4MWCNTs@copolymer was proposed as QuEChERS adsorbent for determinationof 15 mycotoxins and 25 pesticides in grains via liquid chromatography tandem mass spectrometry. The adsorbent was characterized by a transmission electron microscope, scanning electron microscope, elemental analysis, and other techniques. The common matrix interferences were efficiently removed by the proposed adsorbent, such as pigment, fatty acids, and the saccharide. PAGA segment played animportant role in removing the hydrophilic interferences through hydrogen bonding due tothehigh density of hydroxyl groups. PtBMA segment removed the fatty residues through its strong hydrophobic carbon moiety. In comparison with the commercially available QuEChERS adsorbents, the proposed adsorbent had higher adsorption capacities towards the typical matrix interferences. To achieve satisfactory recoveries of analytes, various parameters in theQuEChERS procedure werecomprehensively investigated. Under the optimal conditions, 95.0% of the analytes showedsatisfactory recoveries in the range 70.0-120% as well as negligible matrix effects. The limits of detection (LOD) were in the range 0.00015-1.3μgkg-1. Compared with previously reported QuEChERS methods, the proposed method had improved sensitivity andbenefited from low matrix effects. The recoveries of analytes in various grains were in the range 60.8-108% with relative standard deviations (RSD) less than 13%. Moreover, the Fe3O4MWCNTs@copolymer exhibited good synthetic reproducibility and rapid magnetic separation (less than 10s). The research provides a versatile platform to develop multi-functional QuEChERS adsorbents based on the amphiphilic block copolymer.