GB 23200.53-2016Food safety national standard -- Determination of fenosilazole residues in foodstuffs 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 n-hexane (C6H14). chromatographic purity.

4.1.4 ether (C4H10O). chromatographic purity.

4.1.5 sodium chloride (NaCl). analytical pure, 650 °C burning 4 h, in the dryer to cool to room temperature, stored in a sealed bottle in reserve.

4.1.6 anhydrous sodium sulfate (Na2SO4). analytical pure, 650 °C 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 n-Hexane - Ether (8 2). take 800 mL of n-hexane, add.200 mL of ether, shake and mix.

4.2.2 acetonitrile - toluene (7 3). take 700 mL of acetonitrile, add 300 mL of toluene, shake ready for use.

4.3 Standards

4.3.1 Flusilazole, C16H15F2N3 Si, CAS No. 85509-19-9, molecular weight 315) Standard substance. purity > 99%.

4.4 Standard solution preparation

4.4.1 Fenroxazole standard solution. accurately weighed the appropriate amount of fluorosilicone standard material, with acetonitrile dubbed the concentration of 100 g/mL standard reserve liquid. According to the need to use acetonitrile diluted to the appropriate concentration of standard working fluid. The standard stock solution is stored in 0 °C ~ 4 °C refrigerator, valid for 12 Month, the standard working fluid in 0 °C ~ 4 °C refrigerator to save, valid for 6 months.

4.5 Materials

4.5.1 Graphitized Carbon Black Solid Phase Extraction Column. Envi-Carb, 6 mL, 500 mg or equivalent.

4.5.2 Amino solid phase extraction column. Sep-Pak, 3 mL, 500 mg or equivalent.

4.5.3 Florisil Solid Phase Extraction Column. LC-Florisil, 6 mL, 1 g or equivalent. Before addition, add 5 mL of n-hexane-ether (8 2) Pre-leaching column.

4.5.4 Tandem Column. About 20 mm high anhydrous sodium sulphate was added to the graphitized carbon black solid phase extraction column, and the column was ligated to an amino solid phase extraction the top of the column was pre-leached with 5 mL of acetonitrile-toluene (7 3).

6.1 Tea, grain category

Approximately 500 g of the representative sample was ground and pulverized by a pulverizer and passed through a 2.0 mm round hole sieve, mixed and sealed in a clean container.

mark.

6.2 Vegetables, fruits and nuts

Replace the sample of about 500 g, chopped, the multi-functional food mixer fully mashed evenly, into a clean container sealed, marked the standard Remember.

6.3 Livestock, poultry, aquatic products

Replace the sample of about 500 g, chopped, with a multi-functional food mixer fully mashed uniform, sealed into a clean container, marked mark.

6.4 Bee products category

To replace the sample about 500 g, the crystallization of the sample will be forced to stir evenly, the crystallization of the sample can be sealed after the sample cap, Placed in a water bath of not more than 60 ° C warm, and so the sample all melted and then stir, quickly cooled to room temperature. In the melting must pay attention to prevent water Points volatile. Sealed in a clean container and marked with a mark.

Tea, cereals, bee products, nuts and other samples stored below 4 °C; vegetables, fruits, livestock, poultry, aquatic products such as samples at -18 °C Save the following. In the sample preparation process, should prevent the sample contamination or the occurrence of florfenilazole residue changes.

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

7.1 Extraction

Grain, nuts and tea. Weigh 5 g (2 g of tea) (accurate to 0.01 g) in a 50 mL centrifuge tube, add 5 mL of water Placed for 0.5 h.

Vegetables, fruits, meat and honey. Weigh 5 g (accurate to 0.01 g) sample in 50 mL centrifuge tube, add water 5 mL mix.

Add 20 mL of acetonitrile, 10 000 r/min homogeneous 0.5 min (honey only need to vortex mixing 2 min), add 5 g sodium chloride, shake, and centrifuged at 4 000 r/min for 3 min. Absorb the upper organic phase in the concentrated flask, the residue by adding 15 mL of acetonitrile, repeat the extraction time, and the upper organic phase was concentrated in a 45 ° C water bath under reduced pressure to near dryness. Accurately add 5.0 mL of acetonitrile-toluene (7 3, volume ratio) (fruit, vegetables) or hexane-ether (8 2, volume ratio) (grain, nuts, tea, meat and honey) to dissolve the residue for purification by solid phase extraction column.

7.2 Purification

7.2.1 Fruits and vegetables

Accelerate the extraction of 2.5 mL of the extract into a tandem column, eluting with acetonitrile-toluene (7 3) at a flow rate of 2 mL/min, collecting 10 mL of eluent 10 mL glass centrifuge tube, in 45 °C below the water bath with a nitrogen blowing machine, add 0.5 mL of acetonitrile dissolved and constant volume, gas chromatography-mass spectrometry set.

7.2.2 Grains, nuts, meats, tea and honey

Accurately remove the 2.5 mL extract into the Florisil solid phase extraction column, with 15 mL n-hexane - ether (8 2, volume ratio) Flow rate of 2 mL/min, discard the eluent. Elution with n-hexane-diethyl ether (3 7, by volume), 10 mL of eluent was collected in 10 mL of glass Glass centrifuge tube, in 45 °C below the water bath with a nitrogen blowing machine, add 0.5 mL of acetonitrile dissolved and volume, gas chromatography - mass spectrometry.

7.3 Determination

7.3.1 Gas Chromatography - Mass Spectrometry Reference Conditions

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

B) Column temperature. 70 ° C (1 min) 20 ° C/min 300 ° C (10 min).

C) Inlet temperature. 280 ° C.

D) Interface temperature. 280 ° C.

E) Carrier gas. helium, purity greater than or equal to 99.999%. Flow rate. 1.0 mL/min.

F) Injection volume. 2 µL.

G) Injection mode. pulse splitless injection, pulse pressure 25 psi, delay 0.75 min, 0.75 min after the valve.

H) solvent delay time. 8 min.

I) ion source. electron bombardment source (EI).

J) Ionization energy. 70 eV.

K) Detection method. Select the ion monitoring mode.

L) Select the ion and relative abundance. see Table 1

Table 1 Select the ion and relative abundance

Select ion (m/z) 233 (quant.) Relative abundance (%) 100 34.5 9.2

7.3.2 Quantitative determination

According to the content of fluorosilazone in the sample solution, the standard working solution with the concentration of fenosilazole in the sample solution was selected. Standard working solution and sample the fluorosilazole response in the solution should be within the linear range of the instrument. Standard working solution and sample volume and other volume interspersed injection determination. In the above chromatogram the retention time of flusilazide is about 11.0 mim, and the total ion chromatogram of the standard is shown in Figure A.1 in Appendix A.

7.3.3 Qualitative determination

The standard solution and sample solution are tested according to the conditions specified in 6.3.1, if the sample solution and the standard solution in the same retention time peak Now, it is confirmed by mass spectrometry, after deducting the background of the sample spectrum, the selected ions all appear, while the selected ion from the the abundance ratio is consistent with the relative abundance of the ions associated with the standard, and the fluctuation range is within the maximum allowable deviation of Table 2 (see Table 2) Fluorosilicon is present in the sample. The confirmed sample can be judged to be detected by fluorosilazole positive. The spectrum of the fluorosilazole standard is given in Appendix A.

Figure A.2.

Table 2 Mass Spectrometry Relative Ion Abundance Maximum Allowable Deviation

7.4 Blank test

In addition to the sample, according to the above test 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, recovery and precision of the sample are given in Appendix B.

Appendix A

(Informative)

Chromatograms and spectra

Figure A.1 Total ion chromatogram of the fluorosilicone target substance

Figure A.2 Mass spectrum of fluorosilazole standard substance

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 added concentration (Mg/kg) Recovery rate range% precision range% Sample added concentration (Mg/kg) Recovery rate range% precision range Rice 0.01 65.7 to 81.1 7.88 Tea 0.01 63.1 to 85.1 11.0 0.02 72.5 to 86.0 5.74 0.02 69.0 to 76.0 6.73 0.05 79.0 to 100.8 10.7 0.05 73.6 to 84.2 5.03 Fresh pea 0.01 71.2 ~ 82.3 6.83 Beef 0.01 63.8 ~ 85.3 10.4 0.02 72.5 to 86.0 5.79 0.02 74.5 to 90.0 7.47 0.05 78.6 to 86.4 5.03 0.05 83.0 to 102.2 9.3 Komatsu 0.01 66.9 ~ 86.1 10.0 Chicken 0.01 66.6 ~ 87.3 10.1 0.02 69.0 to 85.5 8.18 0.02 73.5 to 88.5 7.02 0.05 75.6 to 88.2 5.49 0.05 79.2 to 101.0 10.7 Pear 0.01 66.3 ~ 84.0 8.72 Shrimp 0.01 65.3 ~ 88.6 11.9 0.02 72.5 to 86.0 6.78 0.02 75.5 to 93.0 9.03 0.05 73.4 ~ 87.2 5.89 0.05 79.6 ~ 102.4 9.67 Citrus 0.01 72.3 ~ 85.2 8.88 Honey 0.01 66.5 ~ 82.3 8.82 0.02 74.0 to 88.0 6.12 0.02 75.5 to 93.5 7.43 0.05 79.8 to 97.4 7.57 0.05 77.8 to 100.2 9.93 Peanut 0.01 67.8 ~ 80.1 7.79 Soybean 0.01 63.7 ~ 80.6 12.5 0.02 76.0 to 91.5 6.61 0.02 66.5 to 86.0 14.1 0.05 77.4 to 90.6 6.73 0.05 75.0 to 90.0 11.8 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