Microwave-assisted in situ covalent bonding of ZIF-90 coating for SPME-GC-MS determination of pesticide residues in foods

Microwave-assisted in situ covalent bonding enables rapid ZIF-90 SPME coating. • Covalent bonding enhanced coating adhesion stability and thermal resistance. • ZIF-90 based SPME-GC–MS achieves rapid, sensitive multi-pesticide residue detection. In this study, a novel microwave-assisted in situ covalent bonding strategy was developed for the rapid fabrication of zeolitic imidazolate framework-90 (ZIF-90) coated solid-phase microextraction (SPME) fibers. Coupled with gas chromatography–mass spectrometry (GC–MS), the prepared fibers were applied for the determination of multi-pesticide residues in vegetables. Under optimized extraction and desorption conditions, the ZIF-90 coated fiber showed satisfactory linearity for 14 pesticide residues in the range of 0.01–10 μg/L, with correlation coefficients ( R 2 ) of 0.9925–0.9999 and limits of detection (LODs) of 0.0026–0.0779 μg/L. The intra-day and inter-day relative standard deviations (RSDs) for a single fiber were ≤ 7.8% and ≤ 8.9%, respectively, and fiber-to-fiber RSDs ranged from 1.5% to 9.4% ( n  = 6). The method was successfully applied to cucumber and water spinach matrices, with recoveries of 81.1%–118.6%. These results demonstrate that the ZIF-90 composite exhibited outstanding adhesion stability, thermal tolerance (up to 500 °C), and excellent reusability (>70 cycles), which is a promising candidate for the trace analysis of multi-pesticide residues in complex food matrices. Download: Download high-res image (200KB) Download: Download full-size image