Study On The Method Of Rapid Analysis And Detection Of Common Veterinary Drug Multi-residues In Milk

[Objective] In view of the complexity of veterinary drug use by producer and the safety of milk food products, it is urgent to establish and optimize a kind of method to detect and analyze simultaneously multiple kinds of antibiotics and steroid hormone in milk, for instance sulfonamides, quinolones, steroid hormones and tetracycline in this experimental research. Through this method can not only give a hand to daily testing analysis, but provide reference for the national food safety standards and testing method.[Methods] This research has developed and optimized the pre-treatment method for milk sample at first. Weight 5.0 g milk sample in a polypropylene centrifuge tube; then add 5 mL Na2EDTAbuffering solution(PH=6) to sample and vortex-mix tube for 1 min, ultrasonic bath(45℃) for 3 min. To extract the drug residues and precipitate the milk proteins, add 10 mL 5% acetic acid-acetonitrile solution and 2 g NaCl,4 g anhydrous Na2SO4.Vortex-mix the tube for 1min at a medium speed, ultrasonic for 5 min.Centrifuge the sample at 5000rmp for 5 min. Transfer the supernatant to 10 mL glass tube and evaporate the solvent in a water bath set at 40℃ using nitrogen(10-15psi) until the volume is slightly less than 0.5 mL, then dilute with 5 mL buffer solution for purify. Condition an HLB SPE column with 6 mL CH3OH,6 mL H2O followed by 3 mL buffering solution using vacuum or gravity flow. Apply the sample extracts to the SPE cartridges using gravity flow. Wash the SPE and cartridge with 6 mL H2O, then apply vacuum(or positive air pressure) to the SPE to remove excessive liquid. Elute the SPE into a glass tube using 8 mL of 3:7 CHsOH:EAC. Evaporate the elution in a water bath set at 40℃ using nitrogen,then add 1 mL CH3OH. Vortex-mix for 1 min and strain the mixture through 0.22μm millipore filter for analysis. Then develop and optimize the method of qualitative and quantitative analysis by Ultra Performance Liquid Chromatography-QDa, include chromatograph column, mobile phase, gradient elution parameters, the model of scan and so on.[Results] The results indicate that the method limit of detection(LOD) for target compounds was in the range of 0.5～2.0 μg/kg and the mixed standard solution has a good linear relationship in 2-100 ug/kg. Average recoveries of 25 veterinary drugs at three spiked levels(LOQ, fivefold LOQ, tenfold LOQ) in fresh milk ranged from 61.6% to 118.0% with relative standard deviations(RSDs) of 2.6%～13.4% within the group and 6.4%-14.5% between the group while in pure milk is ranged from 62.9% to 119.2% with relative standard deviations(RSDs) of 2.5%～13.1% within the group and 5.8%-14.2% between the group, which can meet the daily work of the rapid detection and analysis of 25 veterinary drugs in milk.[Conclusion] Using the established method, analysis and detect the target compounds in real samples. The results snowed that can basically meet the daily work for milk samples in four kinds of 25 target compounds rapid analysis and detection, and it has higher sensitivity.