Determination of 9 penicillin residues in puffer fish and eels. Application scope and method principle of liquid chromatography-tandem mass spectrometry

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1 Scope of application

Suitable for liquid chromatography-tandem analysis of 9 kinds of penicillin residues of amoxicillin , ampicillin , piperacillin , penicillin G, penicillin V, oxacillin , cloxacillin, nafcillin , and dicloxacillin in puffer fish and eels Mass spectrometry
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2 Principle of the method

Amoxicillin, ampicillin, piperacillin, penicillin G, penicillin V, oxacillin, cloxacillin, nafcillin and dicloxacillin residues in puffer fish and eels are extracted with acetonitrile, and the acetonitrile is removed by rotary evaporation , Make constant volume with water, determine by liquid chromatography-tandem mass spectrometer, and quantify by external standard method
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3 Reagents and materials

Methanol and acetonitrile: chromatographically pure; n-hexane and ammonia are analytically pure; acetonitrile-saturated n-hexane: take 100 mL of n-hexane and 50 mL of acetonitrile in a 250 mL separatory funnel, shake for 1 min, stand still for layering, discard the acetonitrile
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The purity of the standard material is ≥99%
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0mg/mL 9 kinds of penicillin standard stock solutions: accurately weigh an appropriate amount of each standard substance, and prepare a standard stock solution with a concentration of 1.
0mg/mL with water
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9 kinds of penicillin standard working solutions: draw an appropriate amount of each penicillin standard stock solution as needed, and dilute with water to form a mixed standard working solution of appropriate concentration
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4 Instruments and equipment

Liquid chromatography-tandem quadrupole mass spectrometer: equipped with electrospray ion source; analytical balance: sensitivity 0.
1mg, 0.
01g; micro syringe: 25μL, 100μL; graduated sample tube: 5mL, accuracy of 0.
1mL; homogenizer ; High-speed refrigerated centrifuge: with a 50mL centrifuge tube with stopper, the speed can reach more than 10000r/min
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5 Sample pretreatment

(1) Sample preparation

Take out a representative sample of about 1 kg from all the samples, fully mash, mix, and divide them into two parts, and put them into clean containers
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After being sealed, it is used as a sample and marked with a mark
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(2) Preparation of sample solution

Weigh 5g sample (accurate to 0.
01g) into a 50 mL centrifuge tube, add 20 mL of acetonitrile extract, homogenize with a homogenizer for 1 min, and use a high-speed refrigerated centrifuge at 10°C, 10000 r/min Centrifuge for 10 min, and transfer the upper extract to another centrifuge tube
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(3) Preparation of blank sample and standard mixed working solution

Accurately pipette appropriate amounts of 9 penicillin standard mixed working solutions, add them to 5.