β-Ketoenamine-linked covalent organic framework coating for ultra-high-performance solid-phase microextraction of polybrominated diphenyl ethers from environmental samples

Abstract

Covalent organic frameworks (COFs) via Schiff base-type linkages (1,3,5-triformylphloroglucinol–paraphenylenediamine, TpPa-1), as an ideal coating, possesses significant potential for solid-phase microextraction (SPME) due to their fascinating properties, such as outstanding thermal and chemical stabilities, inherent porosity, and high crystallinity. A novel SPME device was fabricated based on TpPa-1 as an enrichment coating for capturing trace polybrominated diphenyl ethers (PBDEs). This TpPa-1 coating exhibited a superior enrichment capacity in “catching” PBDEs over commercial SPME fibers. Such performance is attributed to multiple factors, including the coating’s hydrophobic nature, π-π stacked architectures, large specific surface area, high thermal stability, and size-matching effect. High enhancement factors of 2035–6859, low detection limits of 0.0058–0.022 ng L−1, satisfactory linear range of 0.01–100 ng L−1, good repeatability of 4.86%–9.33%, and excellent reproducibility of 5.62%–9.85% were achieved. Finally, as expected, as the most sensitive SMPE technique for detecting PBDEs, to the best of our knowledge, the developed SPME procedure in combination with gas chromatography–negative chemical ion–mass spectrometry analysis was proven to be ultrasensitive, dependable, and practical in analyzing PBDE species in real water. These exceptional results signify that the proposed method offers a fresh prospect to extend the potential applications of COFs to pick up pollutants at ultra-low levels from environmental samples.