3D macro/mesoporous highly reproducible amino-functionalized covalent organic framework nanospheres for fat-rich foodstuffs pretreatment in nontargeted analysis

Moving from the targeted to nontargeted analysis of chemical hazards in foods is an extremely challenging task for human wellbeing since various types of endogenous and exogenous substances are kept unknown for analysts. Lipids with a wide size distribution are the dominant interference in fat-rich foodstuffs. At present it is difficult to remove all lipids with one material. Herein for the first time, diverse lipids from both animal and vegetable oils are effectively removed and more than 400 chemical hazards with various physicochemical properties are recovered. Such unprecedented function is due to the rational designed three-dimensional (3D) macro/mesoporous amine-functionalized covalent organic framework (COF) nanospheres. In detail, the preparation of macro channels decreases mass transfer resistance. Amino groups and mesoporous are key factors for capturing lipids. Fundamentally it is found that the mechanisms to universally capture free fatty acids (FFAs) and triglycerides (TGs) are hydrogen bonding, size exclusion and size filling, H-π effect, respectively. This has been evidenced by theoretical calculations, isothermal titration calorimetry (ITC), UPC2-Q-TOF/MS and UPC2-MS/MS. Overall, this work highlights the substantial application potential of COF to universal analysis in food safety and integrity.