GB 23200.20-2016Food safety national standard -- Determination of abamectin residues in food by liquid chromatography-mass spectrometry / mass spectrometry (English PDF)

4.1 Reagents

4.1.1 acetonitrile. pure chromatography.

4.1.2 anhydrous sodium sulfate. 650 °C before burning 4 h, in the dryer to cool to room temperature, stored in a sealed bottle in reserve.

4.2 Solution preparation

4.2.1 acetic acid aqueous solution (0.1%). take 1 mL of acetic acid, the volume of water to 1000 mL.

4.2.2 acetonitrile aqueous solution (16, V/V). take 100 mL of acetonitrile, add 600 mL of water, shake back.

4.3 Standards

4.3.1 Avermectin standard substance. (Abamectin, C48H72O14, CAS No. 71754-41-2), abamectin B1a content is greater than 87%, the following abamectin content are avermectin B1a dollars.

4.4 Standard solution preparation

4.4.1 abamectin standard stock solution. Weigh the appropriate amount (accurate to 0.0001 g) abamectin standard substance, acetonitrile dissolved in the preparation of the concentration for 100 g/mL standard stock solution, stored in -18 °C refrigerator.

4.4.2 avermectin standard intermediate. accurate removal of avermectin standard stock solution, diluted with acetonitrile prepared with 1 g/mL concentration of the standard Quasi-intermediate liquid. Store in 4 °C refrigerator.

4.4.3 abamectin standard working solution. according to the need to accurately remove the appropriate amount of avermectin standard intermediate, diluted with acetonitrile and set to the appropriate concentration Degree of standard working fluid. Store in 4 °C refrigerator.

4.5 Materials

4.5.1 Neutral Alumina Solid Phase Extraction Column. 1000 mg, 3 mL.

4.5.2 C18 solid phase extraction column. 1000 mg, 6 mL.

4.5.3 Organic filter. 0.45 m.

5.2 Analysis of balance. 0.01 g and 0.0001 g

5.3 Homogenizer.

5.4 Centrifuge, 3000 r/min or more.

5.5 Vortex Oscillator.

5.6 solid phase extraction device.

5.7 Rotary Evaporator.

5.8 nitrogen blowing instrument.

6.1 Preparation of the sample

6.1.1 Apple, garlic, spinach, chestnut

Apple, chestnut. take the sample about 500 g, crushed with a crusher, into a clean container as a sample, sealed and do a good job; garlic, Spinach. take the sample about 500 g, crushed with a mashed machine, into a clean container as a sample, sealed and do a good job.

6.1.2 Rice, tea, red peony, vinegar

Take about 500 g of the sample and crush it all through a 850 µm sieve into a clean container as a sample, seal and mark it;

Vinegar can be packed in clean containers, sealed and marked.

6.1.3 Beef, lamb, chicken, fish

Take a representative sample of about 500 g, crushed with a mashed machine, into a clean container as a sample, sealed and labeled.

6.1.4 Honey

Take a representative sample of about 500 g, the amorphous sample will be forced to stir evenly, there are crystallization of the sample can be sealed after the sample cap, Placed in a water bath of not more than 60 °C, until the sample all dissolved and stir well, quickly cooled to room temperature. The prepared sample is packed in a clean container Sealed and identified.

Note. The above sample sampling site according to GB 2763 Appendix A implementation.

6.2 Sample storage

Apple, garlic, spinach, chestnut and other samples at 0 °C 4 °C preservation; beef, lamb, chicken, fish and other samples at -18 °C to Frozen under the preservation of rice, tea, red peony, vinegar, honey and other samples stored at room temperature.

During the operation of the sample preparation, the sample should be protected from contamination or changes in the content of the residue.

7.1 Extraction

7.1.1 Garlic, spinach, apple, chestnut, beef, lamb, chicken, fish samples

Accurately weigh 5 g (accurate to 0.01 g) homogeneous sample, add 5 g of anhydrous sodium sulfate and 15 mL of acetonitrile to 10,000 r/min Homogenization 2 min, 3000 r/min centrifugation 5 min, the supernatant was filtered through anhydrous sodium sulfate and into the concentrated bottle. Re-use 10 mL of acetonitrile Take the combined extract once. The extract was concentrated to 2 mL to 3 mL in a water bath at 40 ° C.

7.1.2 Rice, tea leaves, red peony samples

Accurately weigh 5 g (accurate to 0.01 g) homogeneous sample, wet the sample with 2 mL of water (the tea is wet with 20 mL of water) 15 min, add 5 g of anhydrous sodium sulfate and 15 mL of acetonitrile to 10000 r/min homogeneous 2 min, 3000 r/min centrifugation 5 min, the supernatant was transferred to a vial. With 10 mL of acetonitrile and then extracted once, the combined extract. The extract was concentrated to 2 at 40 ° C in a water bath ML-3 mL.

7.1.3 Vinegar, honey samples

Accurately weigh 5 g (accurate to 0.01 g) homogeneous sample, add 30 mL of water and mix well.

7.2 Purification

7.2.1 Rice, garlic, spinach, apple, chestnut, tea, beef, lamb, chicken, fish, red peony

The neutral alumina column was pre-leached with 3 mL of acetonitrile. The sample extracts obtained in 7.1.1 and 7.1.2 were transferred to neutral alumina Column, the flask was washed twice with 5 mL of acetonitrile and the washing solution was transferred to a neutral alumina column. The flow rate was adjusted to about 1.5 mL/min.

2 mL of acetonitrile leach the column to collect the entire effluent. The effluent was dried at 50 ° C, the residue was dissolved in 1.00 mL of acetonitrile, filtered through a filter, Determination by liquid chromatography - mass spectrometry/mass spectrometry.

7.2.2 Vinegar, honey samples

The C18 solid phase extraction column was pre-leached with 5 mL of acetonitrile and 5 mL of acetonitrile in water. Add the sample dilution obtained in 7.1.3 Into the C18 solid phase extraction column, adjust the flow rate of 1.5 mL/min or so, add 10 mL of water to wash C18 solid phase extraction column, the solid phase extraction column dry. Add 5 mL of acetonitrile to elute and collect all eluent. The eluate was dried at 50 ° C, the residue was dissolved with 1.00 mL of acetonitrile, Filtration, for liquid chromatography - mass spectrometry/mass spectrometry.

7.3 Determination

7.3.1 Liquid Chromatography - Mass Spectrometry/Mass Spectrometry Reference Conditions

A) Column. Column. C18 column, 150 mm × 2.1 mm (inner diameter), particle size 5 m.

B) Mobile phase. acetonitrile + acetic acid aqueous solution (0.1%) = 70 30.

C) Flow rate. 0.3 mL/min.

D) Column temperature. 40 ° C.

E) Injection volume. 20 µL.

F) ion source. atmospheric pressure chemical ionization source (APCI source), negative ion monitoring mode.

G) Mass Spectrometer Parameters. See Appendix A.

H) monitoring of ion pair (m/z). qualitative ion pair (872/565,872/854), quantitative ion pair (872/565).

7.3.2 Determination and confirmation of chromatography

According to the content of abamectin in the sample, the standard working solution with similar concentration was selected for chromatographic analysis. The peak area was determined by external standard method Quantitative. The reference retention time of avermectin was 11.3 min under the above chromatographic conditions. Refer to Appendix B for the selection of the standard solution

Figure B.1, Figure B.2.

According to the above conditions to determine the sample and standard working fluid, if the detection of the quality of the peak retention time and standard working fluid consistent; qualitative the relative abundance of the ion pair is consistent with the relative abundance of the standard working fluid at a considerable concentration, and the relative abundance deviation does not exceed the requirements in Table 1.

To determine the existence of the corresponding sample in the sample. The second-order spectrum of the standard solution is shown in Figure B.3 in Appendix B.

Table 1 qualitative relative ion abundance maximum allowable error

7.4 Blank experiment

In addition to the sample, according to the above determination steps.

10.1 Quantitation limits

The quantification limit of this method avermectin was 0.005 mg/kg.

10.2 Recovery rate

The recovery of avermectin is shown in Appendix C when the levels are 0.005 mg/kg, 0.01 mg/kg, 0.05 mg/kg.

Relative abundance (base) 50% 20% to 50% 10% to 20% <=10% Allowable relative deviation ± 20% ± 25% ± 30% ± 50% Appendix A (Informative) Mass spectrometer parameters 1) A.1 Spray pressure. 60 psi.

A.2 Dry gas flow rate. 5 L/min.

A.3 Dry gas temperature. 350 ° C.

A.4 atmospheric pressure chemical ionization source evaporation temperature. 400 °C.

A.5 Corona current. 10000 nA.

A.6 Capillary voltage. 3500 V.

1) Non-commercial statements. The listed parameters are performed on the Agilent LC-MSD-Trap-VL ion trap mass spectrometer, where the test instrument model is listed for reference only, Does not involve commercial purposes, encourage standard users to try to use different manufacturers or models of equipment.

Appendix B

(Informative)

Selective ion chromatogram and secondary mass spectrum of standard solution

Figure B.1 Selective ion flow diagram of the avermectin reference substance (10 ng/mL) (565 m/z)

Figure B.2 Selective ion flow diagram of the avermectin reference substance (10 ng/mL) (854 m/z)

Figure B.3 Secondary spectrum of avermectin standard solution

Appendix C

(Informative)

Sample concentration and recovery of the experimental data Sample concentration and recovery of the experimental data sample name Add concentration (mg/kg) 0.005 0.01 0.05 Rice 67.2% ~ 99.2% 74.6% ~ 90.8% 70.0% ~ 86.6% Garlic 61.6% ~ 85.2% 63.2% ~ 83.4% 72.3% ~ 84.9% Spinach 68.0% ~ 106.8 79.8% ~ 99.6% 81.7% ~ 96.1% Apple 69.2% ~ 100.8% 76.6% ~ 107.6% 73.1% ~ 91.7% Chestnut 78.1% ~ 111.2% 86.1% ~ 102.6% 72.6% ~ 83.6% Tea 69.2% ~ 94.0% 74.8% ~ 85.8% 69.6% ~ 90.6% Beef 61.2% ~ 95.6% 74.6% ~ 92.2% 74.1% ~ 99.1% Lamb 66.0% ~ 76.8% 74.8% ~ 88.4% 68.3% ~ 79.7% Chicken 64.4% ~ 85.6% 74.4% ~ 96.0% 80.4% ~ 101.3% Fish 73.2% ~ 96.8% 74.6% ~ 103.6% 85.2% ~ 97.2% Honey 74.0% ~ 97.2% 74.8% ~ 102.2% 66.6% ~ 87.3% Red peony 64.8% ~ 85.2% 74.6% ~ 87.0% 70.9% ~ 96.9% Vinegar 67.2% ~ 74.4% 65.6% ~ 87.8% 76.2% ~ 85.3% Appendix D (Normative appendix) Laboratory repeatability requirements

Table D.1 Laboratory repeatability requirements

Measured component content Mg/kg Precision <=0.001 36 > 0.01 > 1 14 Appendix E (Normative appendix) Inter-laboratory reproducibility requirements

Table E.1 Inter-laboratory reproducibility requirements

Measured component content Mg/kg Precision <=0.001 54 > 0.01 > 1 19