| Objective:The issue of food safety is a major public health problem.China is a high consumption country of poultry products,and their quality and safety is a hot topic in recent years.At present,poultry products,especially poultry egg products,there are still potential and emerging risks,the most prominent of which is the problem of drug residues.Current studies and standards on chemical hazards in poultry products are mainly focused on one or few categories drugs detection categories is limited to meet the needs of high-throughput detection by regulatory agencies related to farmed products,and the detection of hazards in poultry eggs is still stuck in the determination of average content,which cannot clarify the specific distribution of hazards into poultry eggs.Therefore,this study takes poultry products as the research object,focusing on the outstanding problems in the quality and safety of chemical hazards such as drug residues,common illegal additives,and major environmental pollutants in poultry and egg products,and integrates high-throughput rapid detection methods for poultry products;precise identification of banned drugs and precise identification techniques for chemical hazards in poultry products.The visualization of metronidazole in poultry eggs was carried out to initially explore its spatial distribution characteristics in poultry eggs and to visualize the distribution and determination of metronidazole content in egg yolk.Methods: 1.The current list of chemical hazards that may be present or used in poultry products was sorted out,and a Qu ECh ERS-ultra performance liquid chromatography-triple quadrupole tandem mass spectrometry method was established for 286 chemical hazards in poultry products.The target compounds in samples were selected to be extracted with 1% formic acid acetonitrile(85:15,v/v),and the metal ions in the matrix were chelated by adding Na2 EDTA.The separation was performed on an ACQUITY UPLC BEH C18(2.1 mm×100 mm,1.7 μm)column after cleanup with EMR-lipid packing,and the positive ion mode was methanol: acetonitrile(1:1,v/v)-0.5 mmol/L ammonium fluoride-0.1% formic acid aqueous solution as the mobile phase and acetonitrile-1 mmol/L ammonium fluoride as the mobile phase in the negative ionization mode for gradient separation,scanned by multiple reaction monitoring(MRM),quantified by internal standardization of the standard curve,and applied to the detection of actual samples.2.A method was developed for the analysis of 67 prohibited drugs in poultry eggs by solid-phase extraction-ultra performance liquid chromatography-triple quadrupole tandem mass spectrometry.The poultry egg samples were extracted with Na2EDTA-Mcllvaine buffer solution,and the proteins were precipitated by adding sodium tungstate.After enrichment and purification by an Anavo HLB solid-phase extraction column,the samples were separated on an ACQUITY UPLC HSS T3column(2.1 mm×100 mm,1.8 μm)with 0.1% formic acid aqueous solution-methanol as the mobile phase in the positive ion mode and water-The gradient elution was performed in the positive ion mode with 0.1% formic acid aqueous solution-methanol as the mobile phase and in the negative ion mode with water-acetonitrile as the mobile phase.The qualitative and quantitative analysis was performed in the UPLC-Qq Q-MS multiple reaction monitoring mode,and quantified by the isotopic internal standard method or matrix-matched external standard method,and was applied in practice.3.A preliminary TOF-MALDI-MIS method was developed to characterize the in situ distribution of metronidazole in poultry eggs.The eggs were cultured with metronidazole exposure,egg samples were collected,and the concentration of metronidazole in egg white yolk was determined by ultra performance liquid chromatography-triple quadrupole tandem mass spectrometry.The freezing time and temperature of the eggs and the instrument conditions were optimized.The eggs were sliced by a frozen slicer,dried and coated with α-cyano-4-hydroxycinnamic acid matrix,then sprayed with 1 m L of 50 % methanol solution to characterize the in situ distribution of metronidazole in egg yolk using matrix-assisted laser desorption ionization-mass spectrometry imaging.Results: 1.286 target substances in their respective linear ranges,linear correlation coefficient R2 ≥0.99,limit of quantification(LOQ)range of 0.5~20 μg/kg,spiked recoveries of 55.80%~137.63% and 53.35%~136.03% for eggs and chicken meat,respectively,with relative standard deviations of 1.14%~16.16% and 0.98%~15.93%,respectively.136.03%.211 poultry samples,chicken meat detected 18 drugs,eggs detected 28 drugs,of which 18 egg products detected 12 drugs.2.The 67 banned drugs showed good linearity in the range of 0.1~100 μg/kg with the correlation coefficient R2≥0.99.The limits of quantification of the method were 0.1~0.5 μg/kg.the average spiked recoveries were 56.3%~110.1% and the relative standard deviations were 1.5%~16.8%.a total of 6 drugs were detected in 144 poultry egg samples.3.The quantitative results showed that metronidazole and hydroxymetronidazole had higher concentrations the day after each dose,and the drug concentrations differed significantly between egg whites and yolks;imaging results showed that metronidazole was unevenly distributed in egg yolks,expanding from the center of the yolk outward.Conclusion: 1.The established high-throughput method is simple in operation,high in accuracy and low in cost,which can achieve high-throughput analysis of chemical hazards in poultry products.There are still safety hazards in poultry products,and the supervision of egg products should be strengthened.2.The established solid-phase extraction method for banned drugs is simple in operation and highly accurate,and can provide technical support for the monitoring of banned drugs in poultry eggs.In addition,there is a risk of excessive residues of banned drugs in poultry eggs.3.The preliminary TOF-MALDI-MIS method provides a new technical method for the spatial distribution characteristics of metronidazole in poultry eggs,which is unevenly distributed in eggs.The effects of metronidazole and other drug residues on the nutritional quality of poultry eggs need to be further investigated. |
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