SN/T 5219-2019Determination of Aminopyralid and Amilopic Acid Residues in Exported Food Liquid Chromatography-Mass Spectrometry / Mass Spectrometry (English PDF)

6.1 Sample preparation

Take 500 g of a representative sample, use a tissue masher to process the sample into a slurry, mix well, put it into a clean sample container, and seal it.

And mark it.

6.2 Sample storage

The samples should be frozen and stored below -18°C.

During the operation of sample preparation and storage, the samples should be prevented from being contaminated or from changing the content of residues.

6.3 Extraction

6.3.1 Fruit and vegetable samples

Weigh 10.0 g of the sample, accurate to 0.01 g, and place it in a 50 mL centrifuge tube, add 10 mL of 1% formic acid acetonitrile, 9 500 r/min After 5 min, add 4g of anhydrous methyl sulfate (4.5) and 1g of sodium chloride (4.7), vortex for 10 min, and centrifuge at 9 500 r/min for 5 min.

6.3.2 Grain samples

Weigh 5.0 g of the sample, accurate to 0.01 g, place it in a 50 mL centrifuge tube, add 3 mL of water, vortex to soak the sample, add 10 mL of 1% formic acid acetonitrile, 9 500 r/min, homogenize for 5 minutes, then add 4 g of anhydrous sulfuric acid (4.5), 1 g of sodium chloride (4.7), and vortex.

Shake for 10 min, centrifuge at 9 500 r/min for 5 min.

6.3.3 Meat samples

Weigh 2.0 g of the sample, accurate to 0.01 g, place it in a 50 mL centrifuge tube, add 2 mL of 5 mmoL/L ammonium acetate buffer, and vortex After spin-soaking the sample, add 10 mL of 5% formic acid acetonitrile and 5 mL of acetonitrile saturated n-hexane, homogenize at 9 500 r/min for 5 minutes, and then add 4g MgSO4, 1g NaCl, vortex for 10 min, centrifuge at 9 500 r/min for 5 min.

6.4 Purification

6.4.1 Fruit and vegetable samples

Take 6 mL of the supernatant and add 15 mL pre-added with 150 mg of C18 powder (4.6) and 900 mg of anhydrous sodium sulfate (4.9).

In the heart tube, vortex for 3 min, and centrifuge at 9 500 r/min for 5 min. Pipette 1 mL of the supernatant into a 15 mL centrifuge tube, and blow dry with nitrogen.

Dilute the volume to 1 mL with a 10% methanol aqueous solution, vortex to mix, and pass through a 0.22 µm microporous membrane (4.14) for determination by liquid chromatography tandem mass spectrometer.

6.4.2 Grain samples

Take 6 mL of the supernatant and add 15 mL pre-added with 150 mg of C18 powder (4.6) and 900 mg of anhydrous sodium sulfate (4.9).

In the heart tube, vortex for 3 min, and centrifuge at 9 500 r/min for 5 min. Pipette 2 mL of the supernatant into a 15 mL centrifuge tube, blow dry with nitrogen, and use the volume of 10% methanol aqueous solution was adjusted to 1 mL, vortexed to mix, and passed through a 0.22 µm microporous membrane (4.14) for determination by liquid chromatography tandem mass spectrometer.

6.4.3 Meat samples

Take 6 mL of the supernatant and add 15 mL pre-added with 150 mg of C18 powder (4.6) and 900 mg of anhydrous sodium sulfate (4.9).

In the heart tube, vortex for 3 min, and centrifuge at 9 500 r/min for 5 min. Pipette 5 mL of the supernatant into a 15 mL centrifuge tube, and blow dry with nitrogen.

Dilute the volume to 1 mL with 10% methanol aqueous solution, add 2 mL of acetonitrile saturated n-hexane, vortex to mix, centrifuge at 9 500 r/min for 5 min, Pass the 0.22 µm microporous filter membrane (4.14) for determination by liquid chromatography tandem mass spectrometer.

7.1 Liquid chromatography/mass spectrometry conditions

7.1.1 Chromatographic column. Eclipse Plus C18 chromatographic column, 50 mm×2.1 mm (inner diameter), particle diameter 1.8 µm or equivalent.

7.1.2 Column temperature. 30 °C.

7.1.3 Injection volume. 5 µL.

7.1.4 Mobile phase. A is 0.2% formic acid, 2 mmoL/L ammonium acetate aqueous solution, and B is methanol (4.2).

7.1.5 Flow rate. 0.3 mL/min.

7.1.6 Gradient. See Appendix A, Table A.1.

7.1.7 Mass spectrometry conditions. see Appendix A, Table A.2.

7.2 Liquid chromatography/mass spectrometry detection

Under the best working conditions of the instrument, inject the matrix standard calibration solution, taking the peak area of the analyte as the ordinate, the matrix calibration solution as the ordinate, draw a standard working curve. Use the standard working curve to quantify the sample, and the sample solution to be tested contains amlpicolinic acid and closampidine the response value of the acid should be within the linear range of the instrument detection. Under the above chromatographic and mass spectrometry conditions, the mass chromatogram of the standard substance multi-reaction monitoring See Appendix B.

7.3 Qualitative Liquid Chromatography/Mass Spectrometry

If there are chromatographic peaks in the mass chromatograms of the sample solution and the standard working solution at the same retention time, the allowable deviation is less than ±2.5%, If the abundance ratio of the selected ion and the corresponding ion abundance ratio of the standard product are within the allowable range (see Table 1 for the allowable range), it can be judged the corresponding analyte is present in the sample. Under the conditions of 7.1, the liquid chromatography-mass spectrometry multi-reaction monitoring phase of amlodipic acid and clopyralid the maximum allowable deviation of ion abundance is shown in Table 2.

7.4 Blank test

Except that no sample is added, all are carried out according to the above-mentioned measuring conditions and operation steps.