Determination of 15 quinolones residues in eel and its products by liquid chromatography-tandem mass spectrometry

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1 Scope of application

Products suitable for eel and 15 quinolone ( fleroxacin , ofloxacin , enoxacin , norfloxacin , ciprofloxacin , enrofloxacin , lomefloxacin , danofloxacin , orbifloxacin , difloxacin , sarafloxacin , sparfloxacin , raving oxolinic acid, nalidixic acid, flumequine) residual amount of a liquid chromatography - tandem mass spectrometry
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2 Principle of the method

Fifteen quinolone drug residues in eel and its products were extracted with acetonitrile .
The extract was degreased by n-hexane liquid-liquid partitioning, purified by strong cationic solid phase extraction cartridge, determined by liquid chromatography-tandem mass spectrometry, and quantified by external standard method
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3 Reagents and materials

Acetonitrile, methanol: chromatographically pure; n-hexane, concentrated ammonia, formic acid, ammonium acetate: analytically pure
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Anhydrous sodium sulfate : Burn at 650°C for 4 hours, and store in a sealed container for later use after cooling
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Ammonia + methanol: 25+75
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Formic acid solution: 0.
1%
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Ammonium acetate buffer: 10mmol/L
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15 kinds of quinolone drug standard materials: purity ≥98%
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Standard stock solution: 100mg/L
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Standard working solution: Take an appropriate amount of standard stock solution as needed, and dilute it with formic acid solution + acetonitrile (9+1, v/v) into a mixed standard working solution of appropriate concentration
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Strong cation exchange column (SCX SPE column) or equivalent: 500mg, 3mL
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4 Instruments and equipment

Liquid chromatography-tandem quadrupole mass spectrometer with electrospray ion source; analytical balance: sensitivity 0.
1mg and 0.
01g; tissue masher; vortex oscillator: disperser: rotation speed should reach 10000r/min; ultrasonic generation Nitrogen concentrator; solid phase extraction device; vacuum pump: vacuum degree should reach 80kPa; micro syringe: 1～5mL, 100～1000μL; centrifuge: speed should reach 4000r/min
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5 Sample pretreatment

(1) Sample preparation

Remove the head of the eel, separate the skin and meat, and place the fish skin in a microwave oven.
Heat for 30 seconds at medium and high power, then take out and cut into small pieces.
Cut the fish into small pieces, and put the two into a tissue masher to homogenize , Mix well, put it into a clean container, and mark it
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(2) Extraction

Weigh 5g sample (accurate to 0.
01g) into a 50mL polypropylene centrifuge tube, add about 5g anhydrous sodium sulfate, 25mL acetonitrile , use a disperser, disperse and extract at 10000r/min for 30s, centrifuge at 4000r/min for 5min, Transfer the clear solution to a 50mL colorimetric tube, take another 50mL centrifuge tube and add 15mL acetonitrile, wash the dispersing knife head for 10 seconds, transfer the washing solution to the first centrifuge tube, stir the residue with a glass rod, vortex and shake for 1min, and ultrasonically shake for extraction Centrifuge for 5min at 4000r/min for 5min, combine the supernatant into a 50mL colorimetric tube, add 15mL acetonitrile to the residue, vortex for 1min, centrifuge at 4000r/min for 5min, combine the supernatant into a 50mL colorimetric tube, and dilute the volume of acetonitrile to 50.
0 mL
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After shaking, pipette 10.
0 mL of acetonitrile extract, shake with 2×5 mL of n-hexane to degrease, use a nitrogen concentrator to blow nitrogen to near dryness at 35°C, add 3 mL of ammonium acetate buffer, vortex for 30 seconds, and wait for purification
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(3) Purification

The solution obtained in the extraction step was passed through a strong cation solid phase extraction cartridge at a flow rate of about 1 mL/min, and drained, and then eluted with 1.
5 mL methanol , 3 mL ammonia water + methanol successively , and combined the eluents.
Dry, dilute to 1 mL with formic acid solution + acetonitrile (9+1), and pass through a 0.
22um filter membrane for liquid chromatography tandem mass spectrometry analysis
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(4) Preparation of blank matrix solution

Weigh 5g of negative sample (accurate to 0.
01g), and operate according to the above steps
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