Effective extraction and determination of 9 β-lactams in water and milk samples by a novel magnetic covalent organic framework combined with UPLC-MS/MS

Abstract

β-Lactams (β-LAs) are a class of widely used antibiotics. However, their residues in food may pose a threat to human health. Therefore, it is of great necessity to develop a method that can sensitively and effectively detect β-LAs at trace levels in complex matrices. In this study, a novel functionalized magnetic covalent organic framework was synthesized based on biphenyl-3,3′,5,5′-tetracarbaldehyde and p-phenylenediamine. This material was used as an adsorbent for the effective extraction of 9 β-LAs in water and milk samples, which were analyzed by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The experimental parameters were optimized, then the sensitive and accurate detection method was developed with excellent linearity (R² ≥ 0.9990), low limits of detection (0.001–0.347 µg L⁻¹) and limits of quantitation (0.002–1.051 µg L⁻¹) for β-LAs. Meanwhile, good recoveries (71.7–118.8%) of 9 β-LAs in water and milk samples were obtained with the relative standard deviations (RSD) <10% (n = 5). In conclusion, Fe₃O₄@SiO₂@Ap-COF can be regarded as an effective magnetic adsorbent, and the established method holds significant promise for rapid detection of 9 β-LAs in water and milk samples.