| In the past20years, the application of antibiotics in livestockproduction in increasingly widespread, so the problem of antibioticsresidues in animal foods is attracting our attention. As a broadspectrumantibacterial agent, the antibiotics like penicillins, tetracycline,chloramphenicol are widely used as a feed additive to maintain the healthof livestock and to accelerate their growth. Except that they also widelyapplied in the prevention and treatment of infectious diseases of animals, asthey have many advantages, such as wide antibacterial spectrum, strongantiseptic ability, easy to use and reasonable prices. So the widely use ofantibiotics, will inevitably result in antibiotic residues in animal food,which pose a potential threat to the human health through the food chain.Therefore, a rapid detection of antibiotic residues in milk should beestablished to strengthen the antibiotics residues in milk of Guiyang, whichhas an important practical significance. The pretreatment methods andresearch methodology of antibiotics and penicillins, tetracycline,chloramphenicol residues in dairy products, which are sold in the district ofGuiyang are studied and the result are as follows:(1)Reseach on the pretreatment methods of tetracyclines andchloramphenicols in diverse dairy. The conditions of extraction,purification, enrichment and measurement were optimized, and theorthogonal experiment was carried out. The EDTA–2Na-Mcllvaine buffersolution was selected as extraction solvent, n-hexane purification, WatersOasis HLB solid-phase extraction columnenrichment and purification.Chromatographic separations were accomplished on a Diamonsil C18column (4.6×250mm,5μm) by using a gradient elution profile with amobile phase consisting of0.1%formic acid in water (A) and acetonitrile(B). The wavelength of the UV detector was set at270nm with a flow rateof1mL/min, which were the optimized condition. (2)A sensitive and reliable solid phase extraction(SPE)-HPLC methodwas developed for determination of four kinds of antibiotics. Samples wereultrasonic extracted by EDTA-2Na-Mcllvaine buffer solution. After n-hexane extracted, the inorganic phase layer, was enriched and purifiedby Waters Oasis HLB solid-phase extraction column. The determination of9brands of dairy products is detected in Guiyang by HPLC with UVdetector, using external standard method. The results show that accuraciesranged from84.00%to93.70%, the intra-day and inter-day RSD were lessthan3%, the LODs were0.15-0.30μg/L, respectively. The method issimple, rapid and high sensitive, which was suitable for analysis ofchloramphenicol and tetracycline antibiotics in milk, or other actualsamples. There are no tetracyclines and chloramphenicol residue ofantibiotics in23batches of milk products after our detection.(3) A high performance liquid chromatography(HPLC) method wasestablished for the determination of amoxicillin and penicillins G in milk.Samples were extracted by acetonitrile and the supernatant was centrifugedand evaporated to dryness. The residue was then dissolved in potassiumdihydrogen phosphate solution and purified by HYPERSEP C18solid phaseextraction. The separation of the extract was carried out in a C18columnwith acetonitrile and water as eluent mobile phase and the quantificationwas calculated by external standard method．A good linear relationship(r=0.9995、0.9997）existed for both residues in concentration range of1.0to100.0ng/mL． The average recoveries from milk at the threeconcentrations are ranged from89.25%to94.13%，with relative standarddeviation(RSD) from1.27％to1.43％．The method is easy and simple,which can be applied to determine the concentration of amoxicillin andpenicillins G residues in milk．... |
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