Core-shell MIL-53(Al)–NH2@UiO-66 coated solid-phase microextraction Arrow for the selective enrichment of nine alkylphenols in milk

Abstract

Metal-organic frameworks (MOFs) hold significant potential for sample preparation, but single-MOF materials often face limitations in selectivity and extraction efficiency. To overcome these, a mesoporous MIL-53(Al)–NH2@UiO-66 composites with a core–shell structure was synthesized using an epitaxial growth strategy. This composite leverages the complementary properties of both MOFs, offering enhanced active sites and interaction forces for analytes. The structure and integration of the composite were characterized using Fourier-transform infrared spectroscopy, scanning electron microscopy, and X-ray diffraction, confirming their successful integration. To address the challenge of detecting alkylphenols (APs) in food matrices, known for their endocrine-disrupting properties and low concentrations, a new solid-phase microextraction (SPME) Arrow was fabricated using the MIL-53(Al)–NH2@UiO-66 composite combined with polyacrylonitrile as a binder. APs were detected using ultra-performance liquid chromatography and quadrupole time-of-flight tandem mass spectrometry (UPLC-ESI-Q-ToF/MS). The developed SPME Arrow-UPLC-ESI-Q-ToF/MS method exhibits good linearity (R2 ≥ 0.9958), wide linear range (0.01–1000 μg L–1), and high sensitivity (limits of detection ranging from 0.005 to 0.01 μg L–1) for APs determination. This method was validated for determining nine APs in milk samples from various packing materials, with spiked recoveries ranging from 85.2 % to 115 % and relative standard deviations from 3.4 % to 13.6 %. This study demonstrates the potential of MOF-on-MOF composites in enhancing the performance of adsorbents for SPME pretreatment, offering a promising approach for improving analytical methodologies in food safety.