Hollow Co/Zn-bimetallic ZIF-derived nanoporous carbons with enhanced stability for in-situ solid phase microextraction of halogenated polycyclic aromatic hydrocarbons in fish muscle: Mechanisms and applications.

Co/Zn bimetallic ZIF, its etched analogue, and a subsequently calcined form (CHBZ), were prepared as solid-phase microextraction (SPME) fiber coatings. The CHBZ-SPME coating exhibited high extraction capacity for halogenated polycyclic aromatic hydrocarbons (HPAHs), characterized by excellent stability, strong hydrophobicity, and a porous structure with pore size of 5.63 nm. Accordingly, CHBZ was selected to develop a sampling rate-corrected in-situ SPME-gas chromatography-tandem mass spectrometry method for the simultaneous detection of 15 HPAHs in fish muscle. Adsorption kinetics and isotherm fitting indicated that the process was dominated by single-molecule layer chemical adsorption through inner/outer pore channels. The extraction efficiency of the homemade fibers surpassed that of commercial fibers, attributed to strong π-π stacking, hydrophobic interactions, size-matching effects, and coordination bonds. This method exhibited a wide linear range (1-500 ng/g), a low detection limit (0.16-0.73 ng/g), satisfactory recovery (60.9-89.2%), and good reproducibility.