Rapidly, sensitively and reliably monitoring trace organochlorine pesticides with a self-supported fluorine-functionalized covalent organic framework membrane in water

Abstract

Rapid, sensitive, and reliable analysis of trace organic pollutants such as organochlorine pesticides (OCPs) in aqueous matrices is critical for water quality assessment. In this study, a self-supported fluorine-functionalized covalent organic framework membrane (F-COF membrane) was fabricated via bottom-up functionalization modification at room temperature and employed as a solid-phase microextraction (SPME) coating for the enrichment and determination of trace OCPs in water. The as-synthesized F-COF membrane exhibited a large specific surface area (482.58 m² g⁻¹), superhydrophobicity, abundant surface functional groups (e.g., –CN–, –F, and –NH₂), and excellent stability. Under optimized conditions, the F-COF-based SPME coating achieved superior performance in enriching 20 trace OCPs, with enrichment factors (EFs) as high as 2527–6120, along with outstanding reusability (over 180 extraction cycles). These performance metrics outperformed those of most previously reported SPME coating materials. The efficient enrichment mechanism of the F-COF membrane toward trace OCPs was attributed to the synergistic effects of hydrophobic interaction, halogen bonding, π–π stacking, and size-matching effects. Subsequently, the developed F-COF-based direct immersion solid-phase microextraction coupled with gas chromatography-mass spectrometry (F-COF-DI-SPME-GC/MS) method demonstrated good linearity over the concentration range of 0.1–5000 ng L⁻¹, ultra-low limits of detection (LODs, 0.001–0.065 ng L⁻¹), and high precision, making it suitable for the determination of trace OCPs in water samples. Furthermore, the application of this method to the analysis of real water samples (lake water, river water, and seawater) revealed excellent matrix interference resistance. Satisfactory recoveries were obtained in the range of 86.15–111.14% with relative standard deviations (RSDs) <9.60%, indicating that the proposed F-COF-DI-SPME-GC/MS method is well-suited for the accurate monitoring of OCPs in various real aqueous matrices.