GB 23200.66-2016Food safety national standard -- Determination of Pseudo-mite Residue in Food by Gas Chromatography -- Mass Spectrometry (English PDF)

4.1 Reagents

4.1.1 Acetone (C3H6O). Residue level.

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

4.3 Standards

4.3.1 Pyridine standard (Tebufenpyrad, C18H24ClNO). purity >= 96.5%.

4.4 Standard solution preparation

4.4.1 Preparation of Pymartamine Standard Solution. Accurately weigh the appropriate standard, dissolve with a small amount of acetone, and prepare the concentration of acetone 1.0 mg/mL of standard stock solution. According to the need to use acetone - n-hexane diluted to the appropriate concentration of standard working solution. Store at -18 ° C in the refrigerator,

4.5 Materials

4.5.1 Cleanert Florisil Solid phase extraction column. 500 mg, 3 mL or equivalent.

6.1 Preparation of the sample

6.1.1 Grain

Take a representative sample volume of 500 g, grind all with an attritor and pass through a 2.0 mm round hole screen. Mix, are divided into two as a test Kind, divided into a clean container, sealed, marked mark.

6.1.2 Fruit or vegetables

Take a representative sample 500 g, chopped, followed by the use of food mashed the sample processed into a slurry. Mix well into a clean capacity Inside, sealed, marked mark.

6.1.3 Meat and meat products

Take a representative sample 500 g, fully mashed by the crusher, into a clean container as a sample. Sealed, marked.

6.1.4 Honey and bee products

Take a representative sample volume of 500 g, the crystallization of honey samples will be evenly stirred; on the crystallization of honey samples, in the Sealed, 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.

6.1.6 Nuts

Take a representative sample 500 g, all grinding with an attritor. Mix, are divided into two as a sample, into the clean clean Container, enclosed, marked mark.

6.1.7 Aquatic products

Take a representative sample of 500 g, remove about 1 kg from the sample, take the edible part of the crusher fully mashed evenly Into two copies, respectively, into the clean container as a sample. Sealed and marked.

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

6.2 Sample storage

Grain samples are stored at 0-4 ° C; fruits and vegetables and other samples are cryopreserved at -18 ° C or lower. In sampling and sample preparation During the operation, 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 0.1 g) in a 100 mL stoppered centrifuge tube, add 10 mL of water, add 50 mL of saturated Acetonitrile, homogenized high-speed homogenate extraction 2 min (soy sauce and honey only violent oscillation 10 min), then add 5 g sodium chloride, violent Shock 10 min, 3000 r/min centrifugal 10 min.

7.2 Purification

7.2.1 Liquid/liquid distribution purification

Take 20 mL of extract (spinach, lotus root, strawberry) or 10 mL (peanut, chicken, pork, cod, honey, chestnut and tea) Leaves) transferred to 50 mL with a plug centrifuge tube, add 10 mL of saturated n-hexane, shaking 3 min, standing stratified, abandoned the upper and the mixture was repeated with 10 mL of n-hexane. The n-hexane phase was discarded and the lower acetonitrile phase was collected in a 100 mL concentrated flask.

40 °C water bath concentrated to nearly 1 mL.

7.2.2 Solid phase extraction (SPE) purification

Before use with 5 mL of acetone - n-hexane pre-sprayed Florisil column. The sample was poured into a column and washed with 12 mL of acetone-n-hexane Off, control flow rate less than or equal to 2 mL/min. The whole eluate was collected in a 50 mL concentration flask, concentrated in a 40 ° C water bath to near dryness, Nitrogen blown dry. With acetone - n-hexane dissolved and set to 1.0 mL, 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, 30 °C/min program temperature to.200 °C, keep 10 min, then 50 °C/min the program was heated to 270 ° C for 4 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 pressure mode, column head pressure 1.45 Mpa);

F) Injection volume. 1 µL;

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

H) ionization mode. negative chemical ionization;

I) ion source temperature. 150 ° C;

J) quadrupole temperature. 150 ° C;

K) reactant gas. methane, purity >=99.99%;

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

M) select the monitoring ion (m/z). quantitative 318, qualitative 320,333,335;

N) solvent delay. 4.0 min.

7.3.2 Determination and confirmation of chromatography

According to the sample content of the sample, the selected concentration of similar standard working solution, the standard working solution and sample volume and other volume the response value of pyridoxamine in standard working solution and sample solution should be within the linear range of 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 condition of 7.3.1, the retention time of pyridoxamine was 16.18 min, and the monitoring ion (m/z) which was confirmed by m/z318,320,333,335 (its abundance ratio was 100. 39. 95. 33). According to the quantitative ion m/z318 the amount of external standard method. The total ion chromatogram and full scan mass spectrometry of the gas chromatographic-mass spectrometry of the pyramidamine standard under 7.3.1 Appendix A, Figures A.1 and A.2.

Table 1 Maximum qualitative error of relative ion abundance when qualitative gas chromatography-mass spectrometry

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

10.1 Quantitation limits

The quantification limit of this method is 2 µg/kg.

10.2 Recovery rate

When adding levels of 0.002 mg/kg, 0.004 mg/kg, 0.01 mg/kg, see Table B for the recovery of picamines.

Appendix A

(Informative)

The total ion chromatogram of picarbamate standard substance 1 5 .5 0 1 6 .0 0 1 6 .5 0 1 7 .0 0 1 7 .5 0 1 8 .0 0 1 8 .5 0 Time - - > Abundance TIC. 1 0 0 PPB .D \\ data .ms 1 6 .1 8 5 Min

Figure A.11 Total ion chromatogram of picidamine standard

Mass Spectrometry of Pyridine Acetate Reference Substance 3 0 8 3 1 0 3 1 2 3 1 4 3 1 6 3 1 8 3 2 0 3 2 2 3 2 4 3 2 6 3 2 8 3 3 0 3 3 2 3 3 4 3 3 6 3 3 8 3 4 0 3 4 2 3 4 4 M/z - - > Abundance Scan 1 5 7 5 (1 6. 2 1 0 points). 1 0 0 PPB .D \\ data .ms

Figure A.2 Pymartamine Standard Substance Mass Spectrometry

Appendix B

(Informative)

The recovery rate in different matrices

Table B.1 Addition recovery in different matrices

Sample concentration (µg/kg) Recovery rate range (%) Sample addition concentration (µg/kg) Recovery rate range (%) spinach 2 90.0 ~ 110.0 Codfish 2 90.0 ~ 110.0 4 95.0 to 107.5 4 92.5 to 107.5 10 97.0 to 112.0 10 97.0 to 119.0 2 95.0 to 110.0 honey 2 90.0 ~ 110.0 4 97.5 to 110.0 4 92.5 to 107.5 10 96.0 to 112.0 10 96.0 to 112.0 Strawberry 2 81.5 ~ 100.8 Chestnut 2 95.0 ~ 115.0 4 92.5 to 107.5 4 92.5 to 107.5 10 96.0 to 112.0 10 95.0 to 114.0 peanut 2 90.0 ~ 110.0 tea 2 90.0 ~ 110.0 4 90.0 to 112.5 4 97.5 to 112.5 10 94.0 to 117.0 10 97.0 to 113.0 chicken 2 90.0 ~ 110.0 pork 2 90.0 ~ 110.0 4 95.0 to 107.5 4 92.5 to 112.5 10 94.0 to 112.0 10 94.0 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