Determination of chloramphenicol, thiamphenicol and florfenicol residues in puffer fish, eels and grilled eels-instruments and equipment

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4 Instruments and equipment

Liquid chromatography-tandem mass spectrometer: equipped with electrospray ion source; analytical balance: sensitivity 0.
1mg and 0.
01g; centrifuge: ≥4000r/min; small desktop centrifuge: ≥13000r/min; tissue masher; homogenization Pulping machine; decompression rotary evaporator; ultrasonic water bath; vortex oscillator; polypropylene centrifuge tube: with lid, 50mL, 1.
5mL; core bottle: 25mL; colorimetric tube with stopper: 50mL
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5 Sample pretreatment

(1) Sample preparation

Take out about 500g of the edible part of a representative sample from all the samples taken, mash it evenly with a tissue masher, put it into a clean container, seal it, and mark it
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(2) Extraction

Weigh 5g sample, accurate to 0.
01g, place it in a 50mL polypropylene centrifuge tube, add 75.
0μL of internal standard standard intermediate solution, add 25mL ethyl acetate, 0.
75mL ammonia, 3g anhydrous sodium sulfate , homogenize and extract for 30s, Centrifuge at 4000r/min for 5min, transfer the supernatant to a 50mL colorimetric tube, take another 50mL centrifuge tube, add 20mL ethyl acetate , 0.
60mL ammonia water, wash the homogenizer blade for 10s, and transfer the washing solution to the first centrifuge tube , Stir the residue with a glass rod, vortex and shake for 1 min, ultrasonic shake for 5 min, centrifuge at 4000 r/min for 5 min, combine the supernatant into a 50 mL colorimetric tube, and dilute the volume of ethyl acetate to 50.
0 mL
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(3) Purification

Dissolve the residue in the chicken heart bottle with 2.
00 mL of water, vortex and mix well, sonicate for 5 minutes, add 3 mL of n-hexane, vortex and mix for 30 seconds, stand for layering, discard.
The upper layer of n-hexane, add 3 mL of n-hexane, vortex and mix for 30 seconds , Stand still for layering, transfer part of the lower water phase to a 1.
5mL polypropylene centrifuge tube, centrifuge at 13000r/min for 5min, filter by 0.
2um membrane, and then use liquid chromatography-tandem mass spectrometry to determine chloramphenicol and methylsulfone And florfenicol
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(4) Preparation of blank matrix solution

Weigh 5g of blank sample, accurate to 0.