Application of covalent organic framework as the adsorbent for solid-phase extraction of trace levels of pesticide residues prior to high-performance liquid chromatography-ultraviolet detection.

A covalent organic framework (named as DAAQ-TFP) was prepared via a fast, environmentally-friendly, and easy-to-perform grinding method with 2,6-diaminoanthraquinone (DAAQ) and 1,3,5-triformylphloroglucinol (TFP) as building blocks. The DAAQ-TFP possesses large surface area, high porosity, good thermochemical stability, abundant O atoms and N-H groups, which render it great potential as sorbent for some compounds. It was employed as adsorbent to extract benzoylurea insecticides (BUs) from environmental water, juice, fruit and vegetables samples, followed by their determination with high-performance liquid chromatography (HPLC). The DAAQ-TFP showed a high adsorption capacity for BUs, and the presented method provided a very low limits of detection and high method recoveries. To explore its application potential and also to clarify the possible adsorption mechanisms of the DAAQ-TFP toward BUs, it was tested to extract different types of compounds, proving that the DAAQ-TFP can serve as a superior adsorbent, and adsorption mechanism is mainly based on the π-π stacking and H bonding.