An electrochemically fabricated ZIF-67/[HOEMIM]BF4 coating for the solid-phase microextraction and detection of polycyclic aromatic hydrocarbons

Abstract

Coatings are considered to play a crucial role in solid-phase microextraction (SPME). In this work, a novel coating named ZIF-67/[HOEMIM]BF₄ was fabricated through in situ potentiostatic electrodeposition in methanol solutions containing ZIF-67 precursors and 1-(2′-hydroxyethyl)-3-methylimidazolium tetrafluoroborate ([HOEMIM]BF₄). Compared with the traditional solvothermal method, this method reduced the synthesis time and enabled ZIF-67 to grow directly on the surface of stainless-steel wire, effectively simplifying the preparation process and improving the coating reproducibility. Owing to the inherent characteristics such as high porosity and high thermal and mechanical stability, and the impressive morphological regulation and extraction function of [HOEMIM]BF₄, the developed coating exhibited a prolonged service life and a better extraction capacity for trace polycyclic aromatic hydrocarbons (PAHs) compared to single ZIF-67 and commercial fibers. Under the optimal conditions, the linear range of the ZIF-67/[HOEMIM]BF₄-based SPME-GC method was 0.01–500 μg L⁻¹, and the detection limit was 0.27–5.2 ng L⁻¹. When applied in the determination of PAHs in a real water sample, recoveries between 85.6–117.3% were obtained, indicating the potential of ZIF-67/[HOEMIM]BF₄ in the high efficiency SPME and GC analysis of PAHs.