In Situ Growth of Hierarchical Porous Covalent Organic Framework Coating for Enhanced Solid-Phase Microextraction of Phenolic Compounds

Abstract

Covalent organic frameworks (COFs) as solid phase microextraction (SPME) coating materials can concentrate phenols thousands-fold due to their large surface area and stability. However, the prevalent micropores in COFs hinder the fast mass transfer of target molecules, resulting in extended SPME extraction times. This study addresses this limitation by incorporating hierarchical porous structures into COFs using polystyrene microspheres as hard templates in the in situ growth process of SPME coating. Due to the presence of a hierarchical porous structure derived from the template, the resulting hierarchical porous TpBD coating, termed HP-TpBD, demonstrated enhanced extraction efficiency. It accelerated extraction kinetics for phenolic compound extraction, enabling significantly shortened extraction times. Coupled with gas chromatography-mass spectrometry, a sensitive method featuring a low limit of detection (0.20-0.28 ng⋅L-1), a broad linear range (1.0-1.0×104 ng⋅L-1), and excellent precision (RSD < 8.5%) was established, facilitating the accurate quantitative analysis of phenols in water and soil samples. This work provides insights into developing COF-based SPME coatings for efficient extraction of volatile contaminants.

Keywords: Covalent organic frameworks. Solid-phase microextraction. Hard template. In situ growth. Hierarchical porous. Phenols.