High efficient adsorption of aflatoxins in peanuts by novel covalent organic framework through multiple interactions

Aflatoxins are the most toxic and high-profile mycotoxins with high occurrence in grain and nuts. To effectively adsorb and sensitively detect aflatoxins in peanuts, two novel covalent organic frameworks (TF-COF, TH-COF) were fabricated by Schiff-base reaction of N,N,N',N'-tetra (p-aminophenyl)-p-phenylenediamine with 2,3,5,6-tetra-fluoroterephthaldehyde and terephthalendehyde, respectively. The TF-COF shows higher adsorption capacity (35-44 mg g^-1) for aflatoxins than TH-COF (26-37 mg g^-1) because abundant fluorine functional groups in TF-COF offer more adsorption sites. A sensitive and practical method for determining aflatoxins (G₂, G₁, B₂ and B₁) in peanuts was developed by combining TF-COF-based extraction technology with high performance liquid chromatography-fluorescence detector. The method provides outstanding performance with linear range of 0.025 ng g^-1-20.0 ng g^-1, detection limits of 0.008 ng g^-1-0.15 ng g^-1, recovery of 86.3 %-116 %, and relative standard deviation below 7.8 %. This study opens a new avenue to develop functionalized COF with distinguished performance for adsorbing hazards in food and/or environmental samples.