| Objective: To realize the sensitive and accurate monitoring of fluoroquinolones(FQs)antibiotics in complex food matrices,a magnetic solid phase extraction-ultra high performance liquid chromatography-tandem mass spectrometry(MSPE-UHPLC-MS/MS)method based on zinc(Ⅱ)functionalized magnetic geopolymer(Zn@MGeo)was established in this study.1.Geopolymer was applied to the field of pretreatment and combined with immobilized metal ion affinity chromatography(IMAC)strategy to construct Zn@MGeo sorbent with difunctional binding sites to improve adsorption efficiency,adsorption selectivity and purification effect.2.A MSPE-UHPLC-MS/MS analysis method based on Zn@MGeo was established to realize the sensitive and accurate detection of six kinds of FQs in food samples.Methods: 1.Porous geopolymer was synthesized from calcined kaolin and fumed silica under mild conditions,and then Zn@MGeo hybrid material was prepared by simple coprecipitation and chemical impregnation.The morphology,chemical structure,crystal structure,element content,charge properties,thermal stability,magnetism,hydrophilicity,specific surface area and pore distribution of Zn@MGeo were studied in detail through various characterization techniques.The adsorption isotherm and kinetics of Zn@MGeo were studied by UHPLC-MS/MS and model fitting.By characterizing the Zn@MGeo before and after adsorption of FQs,the adsorption mechanism was studied.2.Applying Zn@MGeo as MSPE sorbent,a MSPE-UHPLC-MS/MS analysis method based on Zn@MGeo was established.Various conditions affecting the extraction efficiency were optimized in detail,and the reusability,stability and batch repeatability of Zn@MGeo sorbent were studied.The established method was verified and applied to the detection of six kinds of FQs in milk and eggs.To explore the practical application prospect of Zn@MGeo,its wide applicability and selectivity were studied.Results: 1.The Zn@MGeo had good thermal stability,magnetic response,hydrophilicity,high specific surface area and porosity.The sorbent had high adsorption capacity and fast adsorption kinetics for FQs.The adsorption isotherm accorded with the Freundlich isotherm model and the adsorption kinetics accorded with the pseudo-second-order kinetic model,indicating that the adsorption process is mainly completed by various interaction forces on the heterogeneous surface.The results of adsorption mechanism study showed that Zn@MGeo with difunctional binding sites could rapidly adsorb FQs through the synergistic action of electrostatic interaction and coordination.2.Under the optimal MSPE conditions,the MSPE-UHPLC-MS/MS analysis method based on Zn@MGeo could be applied to the detection of FQs in milk and egg samples.The method showed high sensitivity(limits of detection 0.005-0.05 μg/kg),wide linear range(0.01-200 μg/kg),good precision(relative standard deviation less than 9.98%),negligible matrix effect(less than±15%)and satisfactory recovery(75.6-103.7%).Zn@MGeo had good stability and reusability,and no obvious decrease in adsorption efficiency and no change in chemical and crystal structure were observed after 9 cycles.The good batch repeatability showed that the preparation process of sorbent and the established analytical method had good robustness.Zn@MGeo was also suitable for extraction of sulfonamides and tetracyclines,but it showed high selectivity for FQs.Conclusion: 1.The Zn@MGeo hybrid material with difunctional sites could be used as excellent MSPE sorbent,which provided a novel solution for highly selective extraction,enrichment and purification of FQs from complex food matrices.The sorbent had the advantages of low cost,mild preparation conditions,good stability,reusability and wide applicability,showing a broad practical application prospect.2.The established MSPEUHPLC-MS/MS analysis method based on Zn@MGeo could meet the requirements of rapid,sensitive and accurate detection of FQs in complex food matrices. |
