One-step fabrication of hydrophobic metal-organic framework@covalent organic framework hybrid as sorbent for high-performance solid-phase extraction of flavonoids

Metal-organic framework (MOF) and covalent organic framework (COF) exhibit excellent extraction per-formance in sample pretreatment, but their wider application is hindered by some inherent drawbacks. Herein, we successfully synthesized a novel MOF@COF hybrid material with large specific surface area, good chemical stability and reusability, which is suitable as a solid phase extraction (SPE) sorbent for the efficient extraction of flavonoids. Importantly, due to the synergistic effect, the obtained MOF@COF hybrid material showing a higher extraction efficiency than individual MOF and COF. This is mainly due to the obtained MOF@COF hybrid material combines the high specific surface area of MOF and multiple interactions (hydrophobic interaction, hydrogen bonding and pi-pi stacking interaction) with flavonoids conferred by the COF structure. Then, a sensitive analytical method for flavonoids with ideal linear range (1-500 ng mL -1), low detection limit (0.15-0.41 ng mL -1) and good repeatability (2.64-6.20%) was de-veloped under optimized conditions. In addition, the MOF@COF hybrid sorbent has better selectivity for hydrophobic targets containing multiple hydrogen bond acceptors/donors. Finally, the established method was applied to the determination of flavonoids in different food samples, and satisfactory recoveries (81.4-102.1%) were obtained, which initially confirmed its applicability.(c) 2023 Elsevier B.V. All rights reserved.

Automated summary

A novel MOF@COF hybrid material with large specific surface area, good chemical stability and reusability was successfully synthesized as a solid phase extraction (SPE) sorbent for efficient extraction of flavonoids. The MOF@COF hybrid material exhibited higher extraction efficiency than individual MOF and COF due to its synergistic effect. A sensitive analytical method with ideal linear range, low detection limit, and good repeatability was developed for flavonoids using the MOF@COF hybrid material as the sorbent. Furthermore, the MOF@COF hybrid sorbent showed better selectivity for hydrophobic targets with multiple hydrogen bond acceptor/donors. The method was successfully applied to determine flavonoids in different food samples with satisfactory recoveries.