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3.
2.
1.
1 Scope of application
It is suitable for the determination of residues of streptomycin , dihydrostreptomycin and kanamycin in milk powder, milk, puffer fish, eel and royal jelly
.
The detection limit of the method: milk, puffer fish, eel, and royal jelly are all 10.
3.
2.
1.
2 Principle of the method
The antibiotic in the sample is extracted with phosphoric acid solution, and the protein is precipitated with trichloroacetic acid , and purified with benzene sulfonic acid type and carboxylic acid type solid phase extraction column
.
Detected by liquid chromatography-tandem mass spectrometer (ESI+) and quantified by external standard method
3.
2.
1.
3 Reagents and materials
Methanol, acetonitrile: chromatographically pure
.
Formic acid, concentrated phosphoric acid, dipotassium hydrogen phosphate (K 2 HPO 4 ), trichloroacetic acid (C 2 HC1 3 O 2 ), sodium heptane sulfonate (C 4 H 15 NaO 3 ·SH 2 O): pure superior grade
5% phosphoric acid solution (1+19, v/v): Take 50mL concentrated phosphoric acid and dilute to 1L with water
.
0.
2mol/L phosphate buffer solution: pH=8.
5
.
Weigh 34.
Trichloroacetic acid solution: 50%, mass fraction
.
Take 20g of trichloroacetic acid and dilute to 20mL with water
0.
01mol/L sodium heptane sulfonate solution: Weigh 2.
20 g sodium heptane sulfonate, dissolve in water, and dilute to 1L
.
SPE elution solution: Take 4 mL of formic acid and dilute to 100 mL with 0.
01 mol/L heptane sulfonate solution
.
25% methanol solution (1+3, v/v): Take 25 mL of methanol and dilute to 100 mL with water
.
Standard material: all purity >98%
.
1.
0mg/mL standard stock solution: Weigh appropriate amounts of streptomycin, dihydrostreptomycin and kanamycin standard substances, respectively dissolve them with 0.
3% acetic acid aqueous solution and prepare 1.
0mg/mL standard stock solutions
.
Store in a freezer at -18°C protected from light
0.
1ug/mL mixed standard solution: draw an appropriate amount of streptomycin, dihydrostreptomycin and kanamycin standard stock solution, dilute with 0.
3% acetic acid water to a 0.
1ug/mL mixed standard solution
.
Store in a freezer at -18°C protected from light
Benzenesulfonic acid type solid phase extraction column (500mg, 3mL) or equivalent
.
Before use, pretreated with 5mL methanol and 10mL water successively to keep the column moist
Carboxylic acid type solid phase extraction column (500mg, 3mL) or equivalent
.
Before use, pretreated with 5mL methanol and 10mL water successively to keep the column moist
.
Filter membrane: 0.
2um
.
3.
2.
1.
4 Instruments and equipment
Liquid chromatography-tandem quadrupole mass spectrometer, equipped with electrospray ion source
.
Analytical balance: Sensitivity 0.
1mg and 0.
01g
.
Liquid mixer
.
Solid phase extraction device
.
Oscillator
.
Vacuum pump: the vacuum degree should reach 80kPa
.
Micro syringe: 25μL, 100uL
.
pH meter: measurement accuracy ±0.
02pH unit
.
Centrifuge tube with stopper: 100mL
.
Graduated centrifuge tube: 5mL
.
Reservoir: 50mL
.
Centrifuge: The speed is above 4000r/min
.
Related links: Determination of residues of aminoglycoside drugs (5)