GB 23200.68-2016Food safety national standard -- Determination of residues of pyridine residues in food by gas chromatography-mass spectrometry (English PDF)

4.1 Reagents

4.1.1 Acetone (C3H6O). Pesticide Residue.

4.1.2 acetonitrile (C2H3N). pesticide residues.

4.1.3 N-Hexane (C6H14). Pesticide Residue.

4.1.4 sodium chloride (NaCl). 650 °C burning 4 h, placed in a dryer cooling, standby.

4.2 Solution preparation

4.2.1 n-hexane saturated acetonitrile. take 100mL n-hexane, 100mL acetonitrile in the separatory funnel, shake and mix, take the next stand.

4.2.2 acetonitrile saturated n-hexane. take 100mL n-hexane, 100mL acetonitrile in the separatory funnel, the oscillation mix, take the upper stand.

4.2.3 Acetone-n-Hexane (3 7, v/v). Take 300 mL of acetone, add 700 mL of n-hexane and shake well.

4.3 Standards

4.3.1 pyridinamide standard substance (boscalid, CAS No. 188425-85-6, molecular formula. C18H12Cl2N2O). purity >= 98.0%.

4.4 Standard solution preparation

4.4.1 Dipyridine standard solution. accurately weighed the appropriate standard with acetone dissolved and prepared into a standard concentration of 1.0 mg/mL reserve liquid. According to the need to use pyridine-free blank sample matrix solution diluted to the appropriate concentration of standard working solution. Store at -18 ° C in the refrigerator.

4.5 Materials

4.5.1 Primary secondary amine (PSA) solid phase extraction column. 500 mg, 3 mL or equivalent.

6.1 Preparation of the sample

6.1.1 Grains and nuts

Take a representative sample volume of 500g, all ground and pass through a 2.0 mm round hole screen. Mix well, into a clean container, sealed, Mark the mark.

6.1.2 Fruits and vegetables

Take a representative sample 500g, chopped (not washable), with a food mashed machine to sample into a slurry. Mix well and put it clean of the container, sealed, marked mark.

6.1.3 Meat and fish

Take a representative sample 500g, fully crushed evenly, into a clean container as a sample. Sealed, marked.

6.1.4 Honey

Take a representative sample 500g, the crystallization of honey samples will be evenly stirred; on the crystallization of honey samples, in the closed the case, the sample bottle placed in not more than 60 °C in the water bath in the warm, shaking, until the sample all melted and stir well, quickly cooled to room temperature, in the melting must pay attention to prevent moisture evaporation. Load a clean container, sealed, marked with a mark.

6.1.5 Tea

Take a representative sample of 500 g, grind all with an attritor and pass through a 2.0 mm round hole screen. Mix well and clean the clean container Inside, sealed, marked mark.

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

6.2 Sample storage

Grains and nuts are stored at 0 to 4 ° C; other samples are cryopreserved at -18 ° C or lower.

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

Weigh 10 g of sample (accurate to 0.01 g) in a 100 mL stoppered centrifuge tube, add 10 mL of water, add 40.0 mL Hexane saturated acetonitrile, homogenizer extraction 2 min (honey need to add water 10mL and acetonitrile violent oscillation 20min), then add 5g sodium chloride, Severe oscillation 10min, 3000 r/min centrifugal 10min, to be purified.

7.2 Purification

7.2.1 Liquid/liquid distribution purification

Take the upper extract 20.0 mL (spinach, carrot, strawberry) or 10.0 mL (peanuts, chicken, onions, cod, honey, chestnut and tea) were transferred to a 50 mL stoppered centrifuge tube, 10 mL of acetonitrile was added to the saturated n-hexane, shaken for 3 min, left to stand, discarded the n-hexane phase was removed and the n-hexane phase was discarded again with 10 mL of acetonitrile saturated n-hexane. The lower acetonitrile phase was collected in 100 mL Concentrated in a 40 ° C water bath and concentrated to approximately 1 mL.

7.2.2 Solid phase extraction (SPE) purification

The PSA column was pre-leached with 5 mL of acetone-n-hexane. The sample solution was poured into the column and eluted with 10 mL of acetone-n-hexane to control the flow rate at 2 mL/min. The whole eluate was collected and concentrated to near dryness in a water bath at 40 ° C. Dissolved with acetone - n - hexane and set to 1.0 mL, determined by gas chromatography-mass spectrometry.

7.3 Determination

7.3.1 Gas Chromatography - Mass Spectrometry Reference Conditions

A) Column. HP-5 MS quartz capillary column, 30 m × 0.25 mm (id), film thickness 0.25 µm, or equivalent;

B) column temperature. the initial temperature of 70 °C, keep 2 min, 25 °C/min program temperature to 150 °C, to 15 °C/min the temperature was raised to.200 ° C, and then the temperature was raised to 280 ° C at 10 ° C/min for 10 min.

C) Inlet temperature. 250 ° C;

D) chromatographic - mass spectrometer interface temperature. 280 ° C;

E) Carrier gas. helium, purity greater than or equal to 99.999%, constant current mode, 1mL/min;

F) Injection volume. 1 µL;

G) Injection method. no split injection, 0.65 min after the opening valve;

H) ionization mode. electron bombardment I) ion source temperature. 230 ° C;

J) quadrupole temperature. 150 ° C;

L) Determination of the way. select the ion monitoring mode;

M) Select the monitoring ion (m/z). Quantitative 140, Qualitative 112, 167, 342;

N) solvent delay. 4.0 min.

7.3.2 Determination and confirmation of chromatography

According to the content of the sample in the sample, select the concentration of similar matrix standard working solution, the standard working solution and sample solution the response value of the solution in the matrix standard working solution and the sample solution to be measured should be within the linear range of the instrument detection.

If the sample solution is in the selective ion chromatogram of the standard working solution, a chromatographic peak appears at the same retention time, in the sample quality chromatogram, the selected ions are present, the abundance of the selected ions is greater than the abundance ratio of the corresponding ions Within the allowable range (see Table 1). Under the above chromatographic conditions, the retention time of pyridine amines was about 18.8 min, and the monitored ions (m/z) which was confirmed by m/z 140, 112, 167, 342 (the relative abundance ratio was 100. 33. 13. 27); according to the quantitative ion m/z140 the amount of its external standard method. The chromatographic total ion chromatogram and full scan of the acridine amide standard under the above chromatographic conditions the spectra are shown in Appendix A, Figures A.1 and A.2.

Table 1 confirms the maximum allowable error of relative ion abundance

Relative abundance (base) 50% 20% to 50% 10% to 20% <=10% Allowable relative deviation ± 20% ± 25% ± 30% ± 50%

7.4 Blank test

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

10.1 Quantitation limits

The limit of quantification of the method is 0.1 mg/kg.

10.2 Recovery rate

When the levels were 0.01 mg/kg, 0.02 mg/kg, 0.04 mg/kg, the addition of pyridinamines was given in Appendix B.

Appendix A

(Informative)

Total Ion Flow Chromatogram and Mass Spectrometry of Pyridinoside Standard Substance

Figure A.11 Total ion chromatogram of pyridinamide standard

Figure A.2 Chromatogram of Pyridinoside Reference Substance

Appendix B

(Informative)

Sample concentration and recovery range of experimental data

Table B.1 Experimental data on sample concentration and recovery range

sample

Add concentration

(Mg/kg)

Recovery rate range (%) sample Add concentration (Mg/kg) Recovery rate range (%) spinach 0.01 90.0 to 110.0 Codfish 0.01 90.0 to 110.0 0.02 97.5 to 112.5 0.02 97.5 to 104.5 0.04 95.0 to 105.0 0.04 94.0 to 112.0 carrot 0.01 95.0 to 111.0 honey 0.01 90.0 to 110.0 0.02 95.0 to 107.0 0.02 92.5 to 102.5 0.04 96.0 to 105.0 0.04 95.0 to 105.0 Strawberry 0.01 95.0 to 110.0 Chestnut 0.01 95.0 to 110.0 0.02 97.5 to 105.5 0.02 92.5 to 107.5 0.04 97.0 to 105.0 0.04 95.0 to 106.0 peanut 0.01 90.0 to 110.0 tea 0.01 90.0 to 110.0 0.02 97.5 to 107.5 0.02 97.5 to 112.5 0.04 98.0 to 107.0 0.04 98.05 to 103.0 chicken 0.01 95.0 to 110.0 0.01 95.0 to 110.0 0.02 96.0 to 107.5 0.02 97.5 to 105.0 0.04 94.0 to 106.0 0.04 95.0 to 112.0 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