Determination Of Residues Of Antibiosis Drugs, Strogens And Contents Of Nutriments In Milk

To investigate the physical properties of fresh milk , the residue of antibiotics and hormone in 510 fresh milk samples of dairy cattle from farmer of five cities(Lanzhou,Tianshui,Hezuo,Wuwei and Linxia) in Gansu province, it was determinated that the physical properties of fresh milk, water, protein, fat, nutrient content and that other major elements with GB method.In addition, it was dectected that the aminoglycosides, sulfa, tetracycline class, quinolones, and other broad categories of antibiotics by using micro-bioanalysis, high-performance liquid chromatography and kit.Besides the dectecting method of three kinds of estrogenous residues(estradiol, diethylstilbestrol and estrone ) in milk was to be found by high-performance liquid chromatography. The results were as follows:(1) The color of milk was no abnormal, and the tissue of milk was a slight viscous phenomenon in the five cities; the relative density of 12 samples were lower than the national standard in Wuwei city. 50 samples with water, protein, fat and nutrient content, and other major elements were determined in five cities, which were found that the protein content was lower than the national standard of samples ,4 in Lanzhou city and 5 Tianshui city;The content of fat was lower than the sample of national standards, 3 samples in Lanzhou city and five samples in Wuwei city.(2) The residue of antibiotics in milk was determined by TTC mthod and paper method, which showed the average positive rate was 9.4%. The minmum detection limit of sulfanilamide group and tetracycline antibiotics was 0.3mg/kg ,0.5mg/kg respectively and the contents were between 0.30 and 1.25mg/L; positive rate was 10.7%,8.0% respectively.Streptomycin,Quinolone,Chlormycetin and sulfamethazine was detected respectively by kit method,which showed average positive rate was 11.7%,3.6%,7.8% and 9%.(3) The efficient method for simultaneous determining three estrogens (estradiol, diethylstilbestrol and norethisterone) in milk by high performance liquid chromatography was developed.The sample was dealed with acetonitrile to remove the protein precipitation supernatant enrichment. Acetonitrile - water (volume ratio , 1: 1) was used for the mobile phase for analysis. Three kinds of estrogen were separated well. The average recovery rate was between 81.6% and 95.8%.The relative standard deviation was between 1.5% and 4.2%.It showed that the minimum detection limit was at 1.0 ~ 2.0 ng / mL.