Photochemical synthesis of magnetic covalent organic framework/carbon nanotube composite and its enrichment of heterocyclic aromatic amines in food samples.

The layered cladding sea cucumber-like covalent organic framework incorporated magnetic carbon nanotube (CTC-COF@MCNT) was prepared by photochemical synthesis. The magnetic composite was fabricated by filling magnetic nanoparticles inside carbon nanotubes and depositing covalent organic framework shell on the outside. The composites exhibited large specific surface area, high stability and adsorption capacity for heterocyclic aromatic amines. Therefore, CTC-COF@MCNT was applied as adsorbent for magnetic solid-phase extraction to enrich the heterocyclic aromatic amines from complex food samples prior to the determination by ultra-high performance liquid chromatography-tandem mass spectrometry. The adsorption mechanism between CTC-COF@MCNT and heterocyclic aromatic amines was discussed and verified by Gaussian simulation. The effect of adsorbent amount, extraction conditions and desorption conditions on the efficiency of pretreatment were optimized. The established method revealed wide linear range and high sensitivity with the LODs ranging from 0.0058 to 0.025 ng/g. Furthermore, the developed method was successfully applied to determine heterocyclic aromatic amines in fried chicken and roast beef. Satisfactory recoveries were obtained, which demonstrated the promising potential of CTC-COF@MCNT as good adsorbent for pretreatment of trace analytes.