GB 23200.19-2016Food safety national standard -- Determination of abamectin residues in fruits and vegetables -- Liquid chromatographic method (English PDF)

4.1 Reagents

4.1.1 Acetone (C3H6O). Chromatographic pure.

4.1.2 Methanol (CH4O). Chromatographic purity.

4.2 Standards

4.2.1 Avermectin standard (molecular formula C48H72O14). purity >= 96.0%.

4.3 Standard solution preparation

4.3.1 Avermectin standard stock solution. Weigh 0.1 g (accurate to 0.0002 g) Avermectin standard in 100mL volumetric flask, with a the alcohol was dissolved and set to a standard stock at a concentration of 1.0 mg/mL.

4.3.2 abamectin standard working solution. according to the need to remove the appropriate amount of avermectin standard stock solution, diluted with methanol to the appropriate concentration of the standard quasi. Standard working fluid should be prepared once a week.

5.1 High Performance Liquid Chromatography. equipped with UV detector

5.2 Analysis of balance. 0.01 g and 0.0001 g

5.3 Tissue crusher.

5.4 Oscillator.

5.5 Rotary evaporator.

5.6 Solid phase extraction column. SPE C18. Specifications. 60 mg/3 mL Activated with 5 mL of methanol and 5 mL of water before use.

6.1 Preparation of the sample

The sample was sorted out 1 kg, the sampling site according to GB 2763 Appendix A implementation, the sample was broken by the organization crusher, are divided into two, Into a clean container, sealed as a sample and marked with a mark.

6.2 Sample storage

Store the sample below -18 ° C.

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

7.1 Extraction

Weigh the sample about 20 g (accurate to 0.1 g) in a 100 mL stoppered conical flask, add 50 mL of acetone, shake on an oscillator at 0.5 H Filtration with a Buchner funnel, washing the conical flask and residue with 20 mL x 2 acetone. The acetone extract was combined and evaporated to about 40 ° C in a water bath 2 mL.

7.2 Purification

The concentrated extract was transferred to the SPE C18 column and rinsed with 5 mL of water to remove the eluent. Finally eluted with 5 mL of methanol, the eluate was collected and purged with nitrogen. Accurately add 1.0 mL of methanol to dissolve the residue, filter with 0.45 µm filter, the filtrate for the liquid phase Chromatography. External standard method.

7.3 Determination

7.3.1 High Performance Liquid Chromatography Reference Conditions.

A) Column. ODS-C18 reverse phase column, 4.6 mm × 125 mm;

B) mobile phase. methanol. water = (90 10, V/V);

C) Flow rate. 1.0 mL/min;

D) Detection wavelength. 245 nm;

E) Column temperature. 40 ° C;

F) Injection volume. 20 µL.

7.3.2 Chromatographic determination

According to the content of avermectin in the sample solution, the standard working fluid in the standard working fluid and the concentration of avermectin in the sample solution should be in the instrument within the linear range of testing, the standard working fluid and sample volume and other volume injection. In the above chromatographic conditions, abamectin retention time About 5.3 min.

For standard chromatograms, see Appendix A, Standard UV Spectra See Appendix B.

7.4 Blank test

Except for the addition of samples, are carried out according to the above measurement steps.

10.1 Quantitation limits

The quantification limit of this method is 0.01 mg/kg.

10.2 Recovery rate

Experimental data on the concentration and recovery of avermectin in apple samples.

The recovery was 82.5% at 0.01 mg/kg.

The recovery was 87.5% at 0.05 mg/kg.

The recovery was 95.0% at 0.50 mg/kg.

The experimental data on the concentration and recovery of avermectin in spinach.

The recovery was 83.0% at 0.01 mg/kg.

The recovery rate was 89.0% at 0.05 mg/kg.

The recoveries were 97.0% at 0.50 mg/kg.

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