Strategy for enhanced selective adsorption of bisphenol compounds in food samples

The issue of selectivity in covalent organic frameworks (COFs) for molecular recognition poses significant challenges. Here, a strategy for designing a flexible ionic bromide magnetic covalent organic framework (iMCOF@Br^-) combined with a magnetic rotor was first proposed and applied to magnetic rotor solid-phase microextraction of bisphenol compounds in food samples. iMCOF@Br^- exhibited ultrahigh adsorption selectivity (98 %) for bisphenol compounds compared with bisphenol analogues (12 %). In particular, the introduction of flexible bromide cations significantly improved the adsorption kinetics (1 min) via electrostatic interactions with the target bisphenol compounds. DFT calculations further revealed that ions can regulate the adsorption affinity of ionic covalent organic framework toward bisphenol compounds. Based on iMCOF@Br^- coupled with MRSPE-HPLC-UV, the recoveries (87.5 % - 102.3 %) of five bisphenol compounds analyzed simultaneously were satisfactory. This work developed a new method for selectively identifying of bisphenol compounds in water, milk, vinegar, and soy sauce samples.