Facile preparation of metal organic framework modified covalent organic framework for efficient dispersive...

High performance adsorbents are crucial for improving the efficiency of sample pretreatment and ensuring the accuracy and precision of analytical results. In this study, covalent organic framework COF-SCU1 was modified with metal-organic framework ZIF-8 for efficient extraction of toxic basic dyes in food. The prepared COF-SCU1@ZIF-8 exhibited improved dispersibility and more surface negative charges compared to COF-SCU1, thereby showing enhanced adsorption performance for auramine O, rhodamine B, basic orange 21, basic orange 22 and methylene blue. The dispersive solid-phase extraction (D-SPE) for toxic basic dyes based on COF-SCU1@ZIF-8 consumed tiny amount of adsorbent and solvent as well as short operation time. An analytical method for the determination of toxic basic dyes was developed based on D-SPE and high-performance liquid chromatography with detection limits of 0.9-1.6 ng mL^-1. The developed method was applied to the detection of toxic basic dyes in real food samples with recoveries of 88.20-105.83 %.