GB 23200.22-2016Food safety national standard -- Determination of residual residues in nuts and nut products by liquid chromatography (English PDF)

4.1 Reagents

4.1.1 Methanol (CH3OH). Chromatographic Purification.

4.1.2 n-hexane (C6H14). pure chromatography.

4.1.3 Ammonium acetate (CH3COONH4).

4.1.4 Sodium hydroxide (NaOH).

4.2 Solution preparation

4.2.1 Ammonium acetate solution (0.02 mol/L). Weigh 1.54 g of ammonium acetate, add water to a volume of 1000 mL.

4.2.2 sodium hydroxide solution (0.01 mol/L). Weigh 0.40 g sodium hydroxide, add water to volume to 1000 mL, shake back.

4.3 Standards

4.3.1 Constituent granules. Maleic hydrazide, C4H4N2O2, CAS number. 123-33-1, purity >=99.9%.

4.4 Standard solution preparation

4.4.1 suppression of buds standard reserve solution. accurately weighed amount of anti-budding standard material, with sodium hydroxide solution prepared into 1 mg/mL standard Stock solution, the standard solution away from 0 °C ~ 4 °C preservation, shelf life of 6 months.

4.4.2 suppression of buds standard working solution. According to the testing requirements, respectively, to absorb the standard reserve solution in the volumetric flask, with sodium hydroxide dissolved Liquid dilution to the standard preparation of the appropriate concentration of the standard working solution, the standard working solution away from 0 °C ~ 4 °C preservation, shelf life of 1 Month.

4.5 Materials

4.5.1 C18 solid phase extraction column. 3 mL 500 mg, or equivalent. Followed by 4 mL of methanol and 4 mL of sodium hydroxide solution activated after use.

6.1 Preparation of the sample

The edible part of the original sample is reduced to about 500 g, and the sampling site is carried out according to GB 2763 Appendix A and crushed with a sample shredder Through 20 mm round hole sieve particles. Fully mixed, prepared samples are divided into two, into a clean sample container, sealed and marked mark.

6.2 Sample storage

Keep the sample below 5 ° C in dark.

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

7.2 Extraction

Add 20 mL of methanol to the centrifuge tube, homogenize 1 min, 6000 rpm/min centrifugation 5 min, the methanol layer carefully removed to filter 100 mL the residue was extracted twice with 20 mL of methanol and the combined extracts were vortexed at about 40 ° C to about 8 mL in the same heart, with nitrogen to about 2 mL, add 3 mL of sodium hydroxide solution to be purified.

7.3 Purification

The above mixed solution was passed through a C18 column, eluted with 4 mL of sodium hydroxide solution and set to 10 mL for high performance liquid chromatography Determination.

7.4 Determination

7.4.1 High Performance Liquid Chromatography Reference Conditions

A) Wavelength. 330 nm.

B) Column. silica gel column, 3.5 µm, 4.6 mm × 150 mm, or equivalent.

C) Column temperature. 40 ° C.

D) Mobile phase. ammonium acetate solution (4.2.1).

E) Mobile phase flow rate. 0.60 mL/min.

F) Injection volume. 20 µL.

7.4.2 Chromatographic determination

According to the content of buds in the sample solution, the standard working solution with similar peak area is selected, and the standard working solution and sample solution the response values of the standard working solution and the sample solution should be within the linear range of the instrument detection. In the above chromatogram Under the conditions, the retention time is about 3.10 min.

See Figure A in Appendix A for standard chromatograms.

7.5 Blank experiment

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

10.1 Quantitation limits

The limit of quantification of this method is 0.2 mg/kg.

10.2 Recovery rate

When adding levels of 0.2 mg/kg, 0.4 mg/kg, 2 mg/kg, the addition rates for the addition of buds in different matrices are given in Appendix B.

Appendix A

(Informative)

Suppose the standard of the standard

Figure A map of the standard (1.5 mg/L)

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 (mg/kg) Recovery (%) walnut 0.2 82.5 ~ 95.5 0.4 81.2 to 94.8 2.0 90.2 to 100.2 Honey walnut 0.2 83.5 to 96.5 0.4 80.2 to 101.2 2.0 91.0 to 104.9 Chestnut 0.2 80.5 to 94.0 0.4 83.4 to 97.8 2.0 90.2 to 100.6 Sugar fried chestnut 0.2 81.5 to 99.5 0.4 84.2 to 97.8 2.0 90.2 to 102.6 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