Detection Technology Of Six Quinolones Residues In Milk Tofu And Study On Drug Residues In Different Processes

In order to investigate the residues and changes of 6 quinolones in milk tofu in Tongliao area,a high performance liquid chromatography-tandem mass spectrometry(LC-MS/MS)method was established in this study to detect the residues of six quinolones in milk tofu.The mass spectrometry conditions,mobile phase,sample extractant,complex solution,and solid phase extraction cartridge were optimized respectively.The residues of 6 quinolone drugs were studied.The results of the study are as follows:To establish a high-performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS)method for the detection of 6 quinolones residues in animal derived food milk tofu.The milk tofu sample was extracted with 0.1 mmol/L EDTA-Mcllvaine buffer and added with 0.1 ml each of ferrocyanide and zinc acetate,purified by HLB Pro solid phase extraction column,and passed through Shim-pack FC-ODS(150 mm×20 mm,3μm)separation,10 mmol/L ammonium acetate(containing 0.1%formic acid)-methanol acetonitrile(40:60,V/V)for gradient elution,and detection in full scan(full MS)mode.The results showed that the 6quinolones had good linearity in the concentration range of 10-100 ng/ml,the correlation coefficient(R~2)was all greater than 0.995;the detection limit(LOD)was0.5-1.5μg/Kg,and the limit of quantification(LOQ)was 2-4μg/kg,the recovery rate of standard addition is 82.3%-101.6%,and the relative standard deviation is less than 10%.his method is highly sensitive,rapid and accurate,and is suitable for rapid screening and quantitative qualitative analysis of 6 quinolones in milk tofu.After the fresh milk was made into milk tofu through three different processing techniques,the established high performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS)method was used to conduct drug testing on the three types of milk tofu in the process of heating and fermentation.Degradation studies.After testing,6 kinds of quinolones in the finished milk tofu were degraded.Among them,the degradation rates of Enr,Cip and Nor in cooked milk tofu were 1.39%,4.73%and 0.86%,respectively,which were lower than those of yogurt tofu and white milk tofu.The degradation rates of Enr,Cip,Spa,and Flu in yogurt tofu were 15.90%,16.52%,12.45%,and 21.64%,respectively,which were higher than those of cooked milk tofu and white milk tofu.In conclusion,six quinolones in milk tofu can be degraded by heating and fermentation methods.