Efficient and selective solid-phase microextraction of polychlorinated biphenyls by using a three-dimensional covalent organic framework as functional coating.

Developing functional fiber coating for selective solid phase microextraction (SPME) of trace pollutants is critical in environmental analysis. Herein, the novel covalent organic frameworks (COFs) with three-dimensional (3D) frameworks and multiple interactions were designed and presented for the selective SPME of polychlorinated biphenyls (PCBs). Using tetra (p-aminophenyl) methane (TAM) and 1,3,5-triformylphloroglucinol (Tp) as the monomers, the 3D TpTAM-COF was synthesized and possessed a large specific surface area, high thermal stability, and spatial selectivity toward PCBs. Characterizations such as morphology, XPS, XRD, thermal stability, and enhancement factors (EFs) were studied. Multiple interactions including π-π conjugation, hydrophobic interaction, and selectivity toward non-planar structure were adopted, which resulted in a superior adsorption affinity toward PCBs on TpTAM-COF. Under the optimal conditions, the spatial selectivity toward PCBs, organic analogs (o-dichlorobenzene, biphenyl) and polycyclic aromatic hydrocarbons (naphthalene, pyrene, and anthracene)) was achieved. Efficient and selective adsorption of fifteen PCBs was fulfilled with the highest EF up to 10305. Using the HS-SPME-GC-MS method, the recoveries of PCBs in the river water and soil samples were determined to be 84.8 ± 7.8% ∼ 117.2 ± 8.5% (n = 3) and 84.4 ± 8.6% ∼ 114.7 ± 7.6% (n = 3), respectively. Compared with most commercial SPME fibers and other COFs-based fibers, the resultant TpTAM-COF-coated fibers possessed higher selectivity and EFs of PCBs. It proposed a promising approach for selective SPME of trace PCBs by multiple interactions in the steric structure of 3D COFs.