Detection of veterinary drug residue parameters 222486

7 Measurement steps 7.1 Extraction 7.1.1 Animal liver, kidney, muscle tissue, and aquatic product Weigh 5g of homogeneous sample (accurate to 0.01 g) and place it in a 50 mL polypropylene centrifuge tube, using approximately 20 mL of 20 mL and 10 mL of 0 1 mol/L EDTA McCllvine buffer solution (4.11) was extracted three times in an ice water bath using ultrasonic extraction. Each time, the mixture was mixed for 1 minute, followed by ultrasonic extraction for 10 minutes. The supernatant was centrifuged at 3000 r/min for 5 minutes (at a temperature below 15 ℃), and the supernatant was combined (note that the total volume of the extraction solution should not exceed 50 mL). The mixture was brought to a constant volume of 50 mL, mixed well, and centrifuged at 5000 r/min for 10 minutes (at a temperature below 15 ℃). The supernatant was filtered with a rapid filter paper and purified. 7.1.2 Weigh 5 g of mixed sample (accurate to 0.01 g) of milk and place it in a 50 mL colorimetric tube. Dissolve it in 0.1 mol/L EDTA McCllvine buffer solution (4.11) and bring to a constant volume of 50 mL. Vortex mix for 1 minute, sonicate in an ice water bath for 10 minutes, transfer to a 50 mL polypropylene centrifuge tube, cool to 0 ° C~4 ° C, centrifuge at 5 000 r/min for 10 minutes (temperature below 15 ° C), filter with a fast filter paper, and wait for purification. 7.2 Purification: Accurately extract 10 mL of the extraction solution (equivalent to 1 g of sample) and pass it through the HLB solid-phase extraction column (4.14) at a rate of 1 drop/s. After the sample solution has completely flowed out, rinse it with 5 mL of water and 5 mL of methanol+water (4.12) in sequence, and discard all the effluent. Reduce the pressure below 2.0 kPa and drain for 5 minutes, and finally elute with 10 mL of methanol and ethyl acetate (4.13). Concentrate the eluent by blowing nitrogen to dryness (at a temperature below 40 ℃), dissolve the residue in 1.0 mL (liquid chromatography-mass spectrometry/mass spectrometry) or 0.5 mL (high-performance liquid chromatography) methanol trifluoroacetic acid aqueous solution (4.16), pass through a 0.45 pm filter membrane, and wait for determination

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