Determination Of 28 Quinolones Residues In Milk And Eggs By LC-MS/MS

Quinolones are a kind of synthetic antimicrobial drugs,which have the same parent structure.Through the continuous modification and modification of their structure,the types of quinolones are very large,and their pharmacological effects are constantly expanding.Because of its broad antibacterial spectrum,strong bactericidal power,no cross-resistance with other antibacterial drugs,and low price,it is widely used in treating a variety of infectious diseases in humans and animals.However,with the extensive use of quinolones,especially in the process of animal breeding,the phenomenon of irrational use of drugs such as abuse and non-compliance has caused food safety problems and quinolones resistance increasingly serious.China has formulated the maximum residue limits of some quinolones in some animal tissues and banned some drugs for food animals.This experiment established a LC-MS/MS multi-residue detection method for 28 quinolones in milk and eggs and meanwhile simultaneous detection of these 28 quinolones was achieved,including fleroxacin,cinoxacin,ofloxacin,pazufloxacin,ciprofloxacin,pefloxacin,orbifloxacin,antrofloxacin,difloxacin,gemifloxacin,sarafloxacin,enoxacin,sparfloxacin,moxifloxacin,danofloxacin,enoxacin,nalfloxacin,oxolinic acid,balofloxacin,nalidixic acid,tosufloxacin,fluoromethine,lomefloxacin,gatifloxacin,norfloxacin,marbofloxacin,pipemidic acid and rufloxacin.In this experiment,formic acid-acetonitrile and acetic acid-acetonitrile were used as extracts of milk and eggs to extract drugs and protein,and then collected supernatant was purified by removing the fat and the pigment by using n-hexane saturated with acetonitrile.After being evaporated by nitrogen,it was re-dissolved in 0.1 % formic acid aqueous solution through an organic filter,using 0.1% formic acid aqueous solution and acetonitrile as phase.This 28 quinolones was separated by Lunna C18 reversed-phase column in 17 min,in positive ion mode MRM multi-channel detection of mass spectrum analysis.In this experiment,matrix matching standard method was used in eggs and milk for scalar.The linear relationships between the 28 quinolones in their linear range performed excellently,and the correlation coefficients were all above 0.99.In the milk and eggs,the corresponding low,medium and high concentrations of the drug were added for the recovery experiment.In the milk tissue,the average recovery rate of the 28 quinolones was 55.8%~113.8%,and the intra-assay coefficient of variation was 0.4%~16.4%.The inter-assay coefficient of variation was 2.1%~12.1%.In eggs tissue,the average recovery rate of 28 quinolones was 56.0%~105.0%,and the intra-assay coefficient of variation was 1.3%~15.1%.The inter-assay coefficient of variation was 2.7%~12.6%.The limit of detection and the limit of quantification of the 28 quinolones in milk and eggs tissues were 0.2~2μg/kg and 0.5~5 μg/kg.The experimental results show that the 28 quinolones LC-MS/MS detection methods in milk and eggs tissue established in this study are simple in operation,with high detection sensitivity and good reproducibility,and meet the requirements of residue detection.