Single-step template-free synthesis of fluoro-functionalized covalent organic frameworks with a tunable hollow structure for extraction of phthalate acid esters from human urine

Abstract

Phthalate acid esters (PAEs) are recognized as endocrine disruptors, exhibit carcinogenic characteristics, and have the potential to impair fertility, thereby posing significant risks to both the environment and human health. Consequently, biomonitoring and exposure assessment of PAEs are of paramount importance. Presently, the majority of detection methods for PAEs are centered on aqueous matrices, and the development of techniques for the identification of PAEs in complex matrices remains an area of active research. This paper designed and synthesized a novel fluoro-functionalized hollow covalent organic framework (F-HCOF), characterized by a tunable hollow spherical structure and enriched with fluorine functional groups, through a one-step self-template approach, which effectively regulated the formation of the hollow structure. The synthesized F-HCOF with tunable hollow structures and abundant F functional groups provided efficient diffusion pathways and adsorption sites, facilitating robust and selective adsorption of the target PAEs. Using F-HCOF as a coating, a solid-phase microextraction method was developed to extract PAEs from complex matrices. The method exhibited limits of detection ranging from 0.0108 to 0.0581 ng L−1, with enrichment factors spanning from 2535.3 to 8985.3. The self-made F-HCOF fibers demonstrated the capability to effectively enrich PAEs under various interference conditions, further verifying their feasibility for practical sample analysis. This work provided a strategic approach for the synthesis of F-functionalized hollow COF adsorbents and explored the formation process of hollow spheres. It enables matrix interference-resistant analysis of PAEs, and offers a practical method for studying PAEs exposure and metabolism within the human body.