GB 23200.31-2016Food safety national standard -- Determination of permethrin residues in food by gas chromatography-mass spectrometry (English PDF)

4.1 Reagents

4.1.1 Acetonitrile (CH3CN). Chromatographically pure.

4.1.2 Toluene (C7H8). Chromatographic pure.

4.1.3 Ethyl acetate (C4H8O2). Chromatographic purity.

4.1.4 n-hexane (C6H14). chromatographic purity.

4.1.5 anhydrous sodium sulfate (Na2SO4). 650 °C burning 4 h, stored in a sealed container for use.

4.2 Reagent preparation

4.2.1 acetonitrile saturated n-hexane. take a small amount of acetonitrile added to n-hexane, vigorous shaking, and continue to add acetonitrile to appear obvious stratification, static for use.

4.2.2 acetonitrile - toluene (3 1). take 300 mL of acetonitrile, add 100 mL of toluene, shake back.

4.3 Standards

4.3.1 Propoxifenone (Flumioxazin, CH15FN2O4, CAS.No. 103361-09-7) Standard. Purity > 99%.

4.4 Standard solution preparation

4.4.1 propafenone standard solution. accurately weighed the appropriate amount of propafenamine standard, with acetonitrile prepared into a concentration of 100 µg/mL Standard stock solution, this solution is stored in a brown volumetric flask, 0 °C ~ 4 °C under the conditions of preservation. Dilute the stock solution with acetonitrile as needed, Prepared into the appropriate concentration of the standard working fluid, 0 °C ~ 4 °C under the conditions of preservation.

4.4.2 matrix standard working solution. matrix standard working solution is the appropriate amount of propafenone standard use of liquid, with blank matrix extract Prepare the appropriate concentration of matrix standard working solution. Matrix standard working solution should be used with the current distribution.

4.5 Materials

4.5.1 LC-NH2 Amino solid phase extraction column. 3 mL, 0.5 g or equivalent.

6.1 Soybeans, rice and almonds

500 g of the sample was taken and pulverized and passed through a sample sieve having a pore size of 2.0 mm. Mixed evenly divided into two, Into a clean container, sealed and marked; stored at -4 °C in dark.

6.2 Spinach, apples and ginger

Remove the sample by at least 500 g, cut it into small pieces, homogenize the sample with a tissue mill and mix it evenly into two pieces.

Clean sample bag, sealed and marked; stored at -18 °C in dark.

6.3 Fish, chicken, pork and liver

Substituting the sample at least 500 g, chopping and homogenizing the sample with a tissue masher, evenly divided into two portions, packed in a clean sample Bag, sealed and identified; in -18 °C dark preservation.

During the operation of the sample preparation, it is necessary to prevent the sample from being contaminated or the change in the content of the residue.

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

7.1 Extraction

7.1.1 Soybeans, rice and almonds

Weigh 5 g of sample (accurate to 0.0 1 g) in a 50 mL centrifuge tube and extract with 15 mL of acetonitrile for 3 min, R/min centrifugation 3 min, the extract into another centrifuge tube, respectively, with 15 mL, 10 mL acetonitrile repeat the above operation once, combined to mention Take the solution into the centrifuge tube, add 5 mL of acetonitrile saturated n-hexane, shake 2 min, centrifuged at 4 000 r/min 3 min, discarded Alkane layer. The acetonitrile layer was transferred to a 250 mL concentrated flask, concentrated in a 45 OC water bath under reduced pressure to near dryness, and 2 mL of acetonitrile-toluene (3 1) Dissolve the residue, to be purified.

7.1.2 Spinach, apples and ginger

Weigh 5 g of sample (accurate to 0.0 1 g) in a 50 mL centrifuge tube, add 5 g of anhydrous sodium sulfate, add 15 mL of ethyl acetate Take 3 min, centrifuge at 5 000 r/min for 3 min, repeat the above operation twice, merge the supernatant to 250 mL concentrated flask , Concentrated in a 45 ° C water bath under reduced pressure to near dryness, add 2 mL of acetonitrile-toluene (3 1) to dissolve the residue, to be purified.

7.1.3 Fish, chicken, pork and liver

Weigh 5 g of sample (exactly 0.0 1 g) in a 50 mL centrifuge tube, add 5 g of anhydrous sodium sulfate, extract with 15 mL of acetonitrile, Fully shaken for 3 min, centrifuged at 4 000 r/min for 3 min, the extract into another centrifuge tube, respectively, with 15 mL and 10 mL B Nitrile The above procedure was repeated once, the extracts were combined, 5 mL of acetonitrile saturated n-hexane was added to the centrifuge tube, shaken for 2 min at 4 000 r/min After centrifugation for 3 min, the n-hexane layer was discarded. The solution was transferred to a 250 mL eggplant flask and the centrifuge tube was washed twice with 5 mL of acetonitrile and washed the polyester liquid was combined into a concentrated flask and concentrated in a 45 ° C water bath under reduced pressure to near dryness. Add 2 mL of acetonitrile-toluene (3 1) to dissolve the residue.

The

7.2 Purification

The LC-NH2 amino solid phase extraction column was pre-leached with 5 mL of acetonitrile-toluene (3 1). The extract was poured into the extraction column and 12 mL Acetonitrile-toluene (3 1) was injected into an extraction column and eluted to collect the eluent. The solvent was purged with nitrogen in a water bath at 45 ° C with toluene Dissolved and fixed to 1.0 mL, gas chromatography - mass spectrometry.

7.3 Determination

7.3.1 Gas Chromatographic Reference Conditions

A) Column. DB-5MS quartz capillary column, 30 m x 0.25 mm (id) x 0.25 m, or equivalent;

B) Carrier gas. helium, purity greater than or equal to 99.995%; constant current mode, flow rate 1.0 mL/min;

C) Column temperature conditions. 60 °C (2 min) 15 °C/min 300 °C (10 min);

D) Inlet temperature. 320 ° C.

E) Injection method. No split injection. After 1 min, open the diverter valve.

F) Injection volume. 2 µL.

7.3.2 Mass spectrometry reference conditions

A) Ion source temperature. 230 ° C B) Transmission line temperature. 300 ° C C) ionization mode. EI D) ionization energy. 70eV E) Select the monitoring ion (m/z). 259,287,325,354.

7.3.3 Qualitative determination

Under the above chromatographic conditions, the retention time of propafenone was about 19.9 min, and the retention time of the compound peaks in the sample to be tested the range of variation should be within ± 0.25 min compared to the standard solution.

In the sample mass spectrum after subtracting the background, the relative abundance of the ions in the monitored ions was chosen to be higher than that of the standard samples of propofluorfen should be consistent, the similarity within the tolerance, see Table 1. The spectrum of the standard spectrum of propafenone is shown in Figures A.1 and A.2 in Appendix A.

Table 1 Comparison of the relative abundance ratio and maximum allowable deviation of phenanthroline

Compound Qualitative ion (m/z) Relative abundance ratio (%) Allowable relative deviation (%) 354.00 100 /325.00 10 ± 50 287.00 33 ± 25 259.00 18 ± 30

7.3.4 Quantitative determination

This method uses the external standard method to quantify the quantitative ion m/z354. In order to reduce the effect of matrix on quantification, we need blank sample to prepare Using the standard working solution of the matrix, according to the sample solution of propafenone out of the peak, select the response value of similar matrix standard working solution Quantitative, standard working fluid and sample volume of the same method of plug-in measurement, the standard working solution and sample solution of propafenone in the response value should be in the instrument Detection within the linear range.

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 is. 0.01 mg/kg.

10.2 Recovery rate

The experimental data on the concentration and recovery of propafenone are shown in Appendix B.

Appendix A

(Informative)

Standard ion chromatogram

Figure A.1 Acetylfluorfenamine standard ion chromatogram

Figure A.2 Propofluorfenamine Standard EI Full Scanning Mass Spectrometry

50 100 150.200 250 300 350 400 450 500 550 M/z - > Abundance 176 52 406 152 129 232 382 578 430 515 470 551 492 Appendix B (Informative) Sample concentration and recovery of the experimental data

Table B.1 Experimental data on the concentration and recovery of the sample

Sample name Add concentration, µg/kg Recovery (%) Rice 10 84.5 98.6 20 91.0102.0 200 95.0 102.5 Soybeans 10 80.3 88.6 20 83.5 95.5 200 88.094.5 spinach 10 73.4 89.6 20 94.0 100.5 200 88.0 100.5 apple 10 88.1 99.6 20 91.597.0 200 90.5 99.5 almond 10 78.5 92.2 20 87.5 95.0 200 86.092.0 pork 10 87.8 94.3 20 92.5 105.0 200 86.0 93.5 chicken 10 85.6 94.1 20 90.5 107.0 200 88.5 94.0 10 75.8 92.8 20 96.5 105.5 200 94.5 100.0 Liver 10 74.1 82.1 20 82.5 91.5 200 87.095.0 10 73.482.3 20 82.5 90.5 200 78.5 87.5 Appendix C (Normative appendix) Laboratory repeatability requirements

Table C.1 Laboratory repeatability requirements

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

Table D.1 Inter-laboratory reproducibility requirements

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