A novel zeolitic imidazolate MOF-on-MOF homostructure for the rapid and sensitive quantification of enrofloxacin in complex food and water matrices.

Enrofloxacin (ENR), a broad-spectrum fluoroquinolone antibiotic, is widely used in both human and veterinary medicine. However, residual ENR in food and water can pose significant health risks. In this study, a novel bimetallic zeolitic imidazolate framework (ZIF-67@ZIF-8) a type of metal-organic framework (MOF), was synthesized at room temperature, and employed as an effective sorbent in a dispersive micro-solid phase extraction (Dμ-SPE) procedure for the rapid and sensitive detection of ENR. The synthesized metal-organic framework-on-metal-organic framework (MOF-on-MOF) material was characterized using Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) analysis. Key experimental parameters, including pH, sorbent amount, adsorption time, and salt concentration, were optimized using a central composite design (CCD). Under optimal conditions, the method showed a linear dynamic range (LDR) of 5-600 ng mL, a limit of detection (LOD) of 1.43 ng mL, a limit of quantification (LOQ) of 4.71 ng mL, and an intra-day relative standard deviation (RSD) of 3.55% (n = 3). Satisfactory recoveries ranging from 89.37% to 101.10% with RSD values below 6.9% were achieved for ENR determination in food and water samples.