In Situ Rapid Electrochemical Fabrication of Porphyrin-Based Covalent Organic Frameworks: Novel Fibers for Electro-Enhanced Solid-Phase Microextraction

Electro-enhanced solid-phase microextraction (EESPME) is a bright separation and enrichment technique that integrates solid-phase microextraction with the electric field. It retains the excellent extraction performance of SPME technology while having the advantages of efficient driving of electric field and special interaction between the electric field and electrons in the molecules of material structure. Replacing conventional SPME fibers with highly efficient and highly conductive original EE-SPME fibers is critical for the practical applications of these technologies. Here, a novel fiber preparation strategy was proposed to obtain a highly conductive porphyrin-based covalent organic framework (POR-COF) by one-step electropolymerization. Benefiting from the excellent semiconducting properties of porphyrin groups, the POR-COF can be spontaneously polymerized on the fiber surface under an appropriate voltage within a few hours. Its performance was evaluated by the EE-SPME of phthalate esters (PAEs) from food and environmental samples, followed by gas chromatography-tandem triple quadrupole mass spectrometry (GC-MS/MS) technology. The results showed that the POR-COF fiber has been successfully used for the detection of trace PAEs in beverages, industrial wastewater, lake water, and oyster samples with high adsorption selectivity and satisfactory sensitivity. The remarkable extraction properties are mainly attributed to the synergistic effect from material characteristics and electrical parameters' control in the extraction process. The presented strategy for the controlled design and synthesis of highly conductive porphyrin-based covalent organic framework fibers offers prospects in developing EE-SPME technologies.