GB 23200.25-2016Food safety national standard -- Determination of Herbicide Residue in Fruits (English PDF)

3.1 Reagents

3.1.1 Benzene (C6H6). heavy distillation.

3.1.2 n-hexane (C6H14). re-distillation.

3.1.3 Sodium chloride (NaCl).

3.1.4 anhydrous sodium sulfate (Na2SO4). after 650 °C burning 4h, placed in the dryer in the spare.

3.2 Solution preparation

3.2.1 benzene - n-hexane solution (1 1). take 100 mL of benzene, add 100 mL of n-hexane, shake back.

3.2.2 benzene - n-hexane solution (2 1). take.200 mL of benzene, add 100 mL of n-hexane, shake back.

3.3 Standards

3.3.1 maloxione standard. purity >= 99%.

3.4 Standard solution preparation

3.4.1 maloxione stock solution. accurately weighed appropriate amount of maloxone standard, with a small amount of n-hexane dissolved, and n-hexane preparation Into a concentration of 1000 µg/mL standard stock solution. The standard stock solution is diluted to the appropriate concentration with n-hexane as needed Quasi working fluid.

3.5 Material

3.5.1 Activated carbon cartridge. SUPELCLEAN ENVI-CARB cartridge, 125 mg, 3 mL or equivalent.

4.2 Analysis of balance. 0.01 g and 0.0001 g

4.3 solid phase extraction device with vacuum pump.

4.4 Centrifuge. 3000r/min.

4.5 Scroll Mixer.

4.6 centrifuge tube. 15mL.

4.7 scale tube. 15mL.

4.8 Micro-syringe. 10 µL.

5.1 Preparation of the sample

Will be taken to take the original sample shrink 1kg, sampling site according to GB 2763 Appendix A, the organization of crusher mashed, are Divided into two, into a clean container, as a sample. Sealed and marked with mark.

5.2 Sample storage

The sample was stored at -18 ° C or lower.

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

6.1 Extraction

Accurately weigh 2.0 g homogeneous sample (accurate to 0.001g) in a 15 mL centrifuge tube, add 1 g of sodium chloride, mix and mixed with 2 mL of the benzene-n-hexane mixed solution on the mixer for 3 min at 2 500 r/min After centrifugation for 2 min, the supernatant was transferred to another 15 mL graduated tube and the residue was washed with 2 mL of benzene-n-hexane the solution was extracted twice, the combined extracts were added, and 1.0 g of anhydrous sodium sulfate was added to dryness.

6.2 Purification

The active carbon pellet was loaded with solid phase extraction on a vacuum filtration device, and the column was pre-leached with 1 ml x3 benzene to keep the flow rate 0.5 mL/min. Remove the eluent. The sample extract was added to a column and washed with a 1.5 mL? 3 benzene-n-hexane mixed solution the tubes were transferred to the pellet and the whole eluate was collected at 45 ° C. The air stream is blown to near and dissolved with n-hexane the residue was set at 0.50 mL for CC/MSD analysis.

6.3 Determination

6.3.1 Gas Chromatography - Mass Spectrometry Reference Conditions

A) Column. quartz capillary column HP-5,25 mx0.2 mm (inner diameter), film thickness 0.33 µm, or equivalent;

B) column temperature. 100 °C for 1min, to 5 °C/min rose to.200 °C, and then 10 °C/min, rose to 280 °C, keep 5min;

C) Inlet temperature. 280 ° C;

D) chromatographic-mass spectrometer interface temperature. 250 ° C;

E) Carrier gas. nitrogen, purity >=99,995%, 0.6 mL/min;

F) Injection volume. 1 µL;

G) Injection method. no split injection, 1min after the opening valve;

H) ionization mode. EI;

I) ionization energy. 70 ev;

J) Measurement method. Select the ion detection mode (SIM);

K) detection of ions (m/z). 177, 258, 344;

L) solvent delay. 20 min.

6.3.2 Chromatographic determination

According to the content of oxadiazone in the sample solution, the standard working solution with similar peak area is selected, the standard working solution and the sample solution are evil the response value of the ketone should be within the linear range of the instrument detection, and the volume of the working fluid and the sample solution should be measured.

Under the above chromatographic conditions, the retention time of oxadiazone was about 25.95 min, and the standard SIM chromatogram and full scan mass spectrum were observed.

Appendix A, Figures A.1, A.2.

6.3.3 Confirmation of mass spectrometry

The standard solution and sample solution are determined according to the conditions specified in 6.3.2, if the sample solution with the standard solution of the same retention Time peak appears, then its mass spectrometry confirmed. Under the above conditions of gas chromatography-mass spectrometry, the retention time of oxadiazone is about for 25.95 min, monitoring of ionic strength ratio (m/z) 258. 177. 344- (65 ± 10). 100. (16 ± 2).

6.4 Blank experiment

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

9.1 Limit of limits

The quantification limit of this method was 0.010 mg/kg.

9.2 Recovery

When the levels were 0.01 mg/kg, 0.05 mg/kg, 0.5 mg/kg, the addition of oxadiazone in different substrates Rate see Appendix B.

Appendix A

(Informative)

Maltose Standard Chromatography and Mass Spectrometry

Figure A A.1 hamstromycin standard SIM chromatogram

Figure A A.2 Vancomycin Standard SCAN Mass Spectrometry

Appendix B

(Informative)

The recovery of maloxione in different matrices

Table B.1 Recovery rates of oxadiazones in different matrices

unit.%

Name of pesticide

Sample matrix

Citrus apple

Oxadiazone 95.0-98.4 96.7-98.3 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