Analytical Methods And Residue Patterns Of Cephalosporins In Animal-derived Foods

Cephalosporins have a greater range of antibacterial spectrum and act as an effective drug in treating some bacterial diseases.There are more than forty cephalosporins have been widely used in human and veterinary pharmaceutical area.,which have also became one of the fastest updates of antibiotic drugs over the past years.The serious issue is that there might be cephalosporin residues on animal source foods which can cause serious food safety problems.High-throughput,high-sensitivity screening methods for cephalosporin residues and their metabolites in animal-derived foods are successfully developed in this research.The elimination of Ceftiofur and Desfuroylceftiofur in hens were further studied.The aims of this study are as followed:To develop a simple and reliable confirmatory LC-MS/MS analytical method for the simultaneous analysis of 23 cephalosporins including almost all the common first,second,third and fourth generation which are all banned for use in meat.To develop an UHPLC-Q-Orbitrap screening method for multi-cephalosporin residues in meat.And the aim is to have a tool for the detection of non-target cephalosporins or even unknowns.To develop the determination method of Ceftiofur and Desfuroylceftiofur using Liquid Chromatography Quadrupole-Orbitrap hybrid mass spectrometry.Besides,the elimination of Ceftiofur in hens were studied according to this analysis method.As a result:1.The selection of separation column and mobile phase greatly influences determinand separation and mass spectrometry results.After optimization of pretreatment conditions,purification methods and stationary phases.Compared with several different common column,the column which have C8 material was applied into cephalosporins’chromatography separation.And 0.1%Formic Acid-water/Acetonitrile was chosen as the most suitable mobile phase.2.Meat is a complex matrix with high contents of protein,fat and phospholipid,which can bind cephalosporins and interfere with their extraction and purification.The extraction solvent and the purification procedure were optimized for obtain the suitable sample treatment procedure.Acetonitrile:water(4:1;v/v)was used as the solvent for the extraction process.And the most promising purificator was Oasis PRiME HLB cartridge.3.This study developed a simultaneous determination method of 23 cephalosporins drug residues in meat using liquid chromatography-tandem mass spectrometry.The linear range of the 23 cephalosporins is 2.0-200.0 μg/kg.The limits of detection(LODs)and limits of quantitation(LOQs)of these compounds were in the range 0.04-3.0 μg/kg and 0.06-10.0 μg/kg,respectively.The average recoveries were in the range 83.3%-110.3%with RSDs(n = 6)lower than 10%.4.This study built a high-accuracy multi-residue screening method of 44 cephalosporins in meat using liquid chromatography Q-Orbitrap hybrid mass spectrometry.The method is validated according to the guidelines specified in Commission Decision 2002/657/EC and the FDA guideline for the bio-analytical assay procedure.The recovery rates ranged from 69.2%to 129.0%with the inter-and intra-day variability under 15%.5.The product ions,produced by high energy collision dissociation(HCD)collision cell,this product ions of cephalosporins were almost always same(identification markers),which could achieve the non-target list qualitative and quantitative detection in a single run.There is a possibility to find newly emerging cephalosporins residue in complex matrix by exploring at the exact mass of these identification markers.6.This study established the determination method of ceftiofur and Desfuroylceftiofur in chicken,liver and kidney using liquid chromatography Q-Orbitrap hybrid mass spectrometry.Besides,the elimination of ceftiofur in hens were studied according to this analysis method.During analysis of three types of matrixes(chicken,liver and kidney),correlation coefficients of linear calibration curves of Ceftiofur and Desfuroylceftiofur were over 0.990 at the corresponding concentration ranges of 2-200μg/kg.The average recoveries of Ceftiofur and Desfuroylceftiofur ranged from 83.2%to 129.7%with the inter-day relative standard deviation(RSD)less than 15%,in spiked samples at three levels.The residues cannot be detected in chicken breast after 12 h,while Ceftiofur and Desfuroylceftiofur could be detected in chicken breast simultaneously during 12 h.The metabolism of Ceftiofur in hens’ liver and kidney were fast.It could totally metabolized to Desfuroylceftiofur during less than 0.5 h.The residue of Desfuroylceftiofur in hens’ liver cannot be detected after 48 h and in kidney cannot be detected after 72 h.This study provided a basis for reference for the future development of long plagued quality and safety issues.