Liquid chromatography-tandem mass spectrometry for the determination of metronidazole, lonidazole and dimetridazole residues in honey

16.
2.
2.
1 Scope of application

Suitable metronidazole in honey, ronidazole , dimetridazole residues Liquid Chromatography - Tandem Mass Spectrometry
.

16.
2.
2.
2 Principle of the method

The three nitroimidazole residues in honey were extracted with ethyl acetate .
After the extract was concentrated, it was purified by BAKERBOND Carboxylic Acid solid phase extraction column, determined by liquid chromatography-tandem mass spectrometry, and quantified by external standard method
.

16.
2.
2.
3 Reagents and materials

Methanol , acetonitrile, ethyl acetate: chromatographically pure; formic acid: excellent grade; anhydrous sodium sulfate : analytically pure
.

Eluent: methanol + acetonitrile + 0.
1% formic acid water (40+18+42, v/v/v)
.

Metronidazole, ronidazole, dimetridazole standard materials: purity ≥98%
.

Standard stock solutions of metronidazole, lonidazole and dimetridazole: 1.
0 mg/mL
.

Metronidazole, ronidazole, dimetronidazole mixed standard working solutions A and B: as needed, draw an appropriate amount of metronidazole, ronidazole, dimetronidazole standard stock solutions, and dilute with methanol to form metronidazole.
1.
0μg / mL, and ronidazole dimetridazole are mixed standard working solution a 2.
0μg / mL of
.

Metronidazole, ronidazole, dimetronidazole mixed matrix standard working solution: draw appropriate amount of metronidazole, ronidazole, dimetronidazole mixed standard working solution A and B as needed, and dilute with the blank sample extract solution Into the mixed matrix standard working solution with concentrations of 0.
25ng/mL, 0.
50ng/mL, 1.
00ng/mL, and 5.
00ng/mL respectively
.

BAKERBOND Carboxylic Acid solid phase extraction column or equivalent: 500mg, 3mL
.

16.
2.
2.
4 Apparatus and equipment

Liquid chromatography-tandem mass spectrometer: equipped with electrospray ion source; analytical balance: sensitivity 0.
1mg and 0.
01g; liquid mixer; solid phase extraction vacuum device; oscillator; stoppered glass centrifuge tube: 50mL; vacuum pump: The vacuum degree should reach 80kPa; centrifuge; rotary evaporator; graduated sample tube: 5mL; pear-shaped bottle: 150mL; simple funnel
.

16.
2.
2.
5 Sample pretreatment

(1) Sample preparation

For laboratory samples without crystals, stir them evenly
.

(2) Extraction

Weigh 10g of sample (accurate to 0.
01g) into a 50mL stoppered glass centrifuge tube, add 10mL of water, mix on a liquid mixer, add 20mL of ethyl acetate, shake on a shaker for 20 minutes at 3000r/ Centrifuge for 5 minutes for 5 minutes, and transfer the supernatant to a simple funnel containing 25g of anhydrous sodium sulfate into a pear-shaped flask
.
Extract again with 20 mL of ethyl acetate , pass through an anhydrous sodium sulfate cylindrical funnel, combine the supernatants, and evaporate to about 2 mL under reduced pressure on a 45°C water bath with a rotary evaporator, and wait for purification
.

(3) Purification

Transfer the above concentrated solution to a Carboxylic Acid solid phase extraction column, and then wash the pear-shaped flask and extraction column with 4 mL ethyl acetate and 4 mL acetonitrile respectively, and discard all the effluent
.
Under a negative pressure of 65kPa, drain the extraction column under reduced pressure for 2 minutes, and use 2 mL of eluent to elute at a flow rate of ≤ 3 mL/min.
Collect the eluent in a 5 mL graduated sample tube and dilute to 2 mL with the eluent.
0.
20μm filter membrane for liquid chromatography-tandem mass spectrometer determination
.

Related links: Determination of linear range and lower limit of metronidazole, ronidazole, dimetronidazole and their metabolites in milk and milk powder