GB 23200.95-2016Food safety national standard -- Detection method of fenpropathrin residues in bee products (English PDF)

4.1 Reagents

4.1.1 Acetone (C3H6O). Distillation.

4.1.2 Sodium hydroxide (NaOH) aqueous solution. 2 m ol/L.

4.1.3 N-Hexane (C6H14). Distillation.

4.1.4 anhydrous sodium sulfate (Na2SO4). 650 °C burning 4 h, stored in a sealed container for use.

4.2 Solution preparation

4.2.1 N-Hexane. Saturated with acetonitrile.

4.2.2 acetonitrile. saturated with n-hexane.

4.3 Standards

Fenvalerate standards. purity >= 97%.

4.4 Standard solution preparation

Accurately weigh the appropriate amount of fenpropathrin standards, with n-hexane dubbed the concentration of 20 µg/mL standard stock solution, and then need to use N-Hexane is formulated into a standard working solution at an appropriate concentration. Store in 4 °C refrigerator.

6.1 Preparation of the sample

The samples will be thoroughly stirred, divided into two, into the sample bottle as a sample, sealed, marked mark. Such as retrieving samples in a knot when the crystal is precipitated, the vial is capped and placed in a water bath which does not exceed 40 ° C. To be all melted after crystallization, open cover, stir well, are divided into two, sealed, and marked with the mark.

In the case of a cup of honey, all the cups of honey will be retrieved, poured together, fully stir well, and take out about 1 kg to represent the sample. And then 1 kg on behalf of the equipment After the samples were mixed, they were divided into two portions and placed in a sample bottle as a sample. Sealed, marked.

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

6.2 Sample storage

Store the sample at room temperature.

Note. During sampling and sample preparation, it is necessary to prevent contamination of the sample or change in the content of the residue.

7.1 Extraction

Weigh about 20 g of sample (accurate to 0.1 g), add 20 mL of sodium hydroxide solution (2 mol/L) to a 125 mL stoppered flask, Oscillation causes the sample to dissolve. Pour into a 100 mL separatory funnel, add 20 mL of n-hexane and 10 mL of acetone, shake for 5 min, standing stratified. will the n-hexane layer was filtered into.200 mL of pear-shaped bottles and 20 mL of n-hexane and 10 mL of acetone were added to the residual night and shaken for 5 min.

Operation once. The n-hexane layer was combined with the pear-shaped flask and evaporated to 40 ° C and evaporated to dryness.

7.2 Purification

The pear-shaped bottle was rinsed with 30 mL of acetonitrile saturated n-hexane and 30 mL of n-hexane saturated acetonitrile and the residue was dissolved. The solution was transferred to 100 mL of the solution Funnel, intense oscillation 5 min, static stratification. Separate the acetonitrile layer into a.200 mL separatory funnel. Add 2 x 30 mL to n-hexane Hexane-saturated acetonitrile, repeat the above procedure. Consolidate the acetonitrile layer in the appendix to the separatory funnel. Add 50 mL of acetone to the separatory funnel and n-hexane, intense oscillation 5 min, standing stratification. The acetonitrile layer was taken in a.200 mL pear-shaped flask and evaporated at 40 ° C or below to just dry. The residue was dissolved in 5.0 mL of n-hexane and the solution was subjected to gas chromatography.

7.3 Determination

7.3.1 Chromatographic reference conditions

A) Column. quartz capillary column, SE-54, 25 m x 0.53 mm (inner diameter), 1.0 µm (film thickness), or equivalent;

B) Carrier gas. nitrogen (purity >=99.99%), 5.7 mL/min;

C) Auxiliary gas. nitrogen, 60 mL/min;

D) Column temperature. 220 ° C;

E) Inlet temperature. 250 ° C;

F) detector temperature. 300 ° C;

G) Injection volume. 1 µL 220 ° C;

H) Injection method. no shunt, 0.75 min after the valve.

7.3.2 Chromatographic determination

According to the sample solution was measured in the case of fenvalerate, selected peak height similar to the standard working solution. Standard working solution and fluoramine in sample solution the cypermethrin response value should be within the linear range of the instrument. On the standard working solution and sample solution volume of the plug-in measurement, in the above-mentioned chromatographic bar , The retention time of fenpropathrin was about 6.6 min, and the standard chromatogram was shown in Figure A1 in Appendix A.

7.4 Blank test

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

10.1 Quantitation limits

The quantification limit of this method is 0.02 mg/kg.

10.2 Recovery rate

The experimental data of the concentration of fenpropathrin in honey and its recovery rate.

At 0.02 mg/kg, the recovery was 93.1%.

At 0.10 mg/kg, the recovery rate was 98.3%.

At 1.0 mg/kg, the recovery was 90.8%.

Appendix A

(Suggested appendix) Standard chromatogram

Figure A1 Gas chromatogram of fluorosaline standard

Appendix B

(Normative appendix) Laboratory repeatability requirements

Table B.1 Laboratory repeatability requirements

Measured component content Mg/kg Precision <=0.001 36 > 0.01 > 1 14 Appendix C (Normative appendix) Inter-laboratory reproducibility requirements

Table C.1 Inter-laboratory reproducibility requirements

Measured component content Mg/kg Precision <=0.001 54 > 0.01 > 1 19