GB 23200.91-2016Food safety national standard -- Determination of 9 organophosphorus pesticide residues in animal-derived foods -- Gas chromatographic method (English PDF)

4.1 Reagents

4.1.1 Ethyl acetate (C4H8O2). Chromatographic purity.

4.1.2 acetonitrile (C2H3N). pure chromatography.

4.1.3 Cyclohexane (C6H12). Chromatographic Purification.

4.2 Solution preparation

4.2.1 GPC eluent. ethyl acetate cyclohexane (1 1, volume ratio). take 100 mL of ethyl acetate, add 100 mL of cyclohexane, shake spare.

4.3 Standards

4.3.1 Organic phosphorus standard. dichlorvos (CAS. 62-73-7), methamidophos, CAS.

10265-92-6), acephate (CAS. 30560-19-1), methyl parathion methyl (CAS.

298-00-0), malathion (CAS. 121-75-5), parathion (CAS. 56-38-2), quinophos (Quinalphos, CAS. 1776-83-6), methidathion (CAS. 950-37-8), triazophos, CAS.

24017-47-8), purity >= 99%.

4.4 Standard solution preparation

4.4.1 dichlorvos, methamidophos, acephate, methyl parathion, malathion, parathion, quinophosphoric acid, methamphetamine, triazolam Quasi-reserve solution. Weigh the appropriate standard, respectively, with acetone dissolved to 100 mL, the solution concentration of 100 g/mL. Before use According to the need to use acetone diluted to the appropriate concentration, as a mixed standard working fluid. Store in 4 °C refrigerator.

7.1 Extraction

Weigh 20 g of the pulverized homogeneous sample (accurate to 0.01 g) in a 100 mL stoppered flask, add 50 mL of acetonitrile at 30 ° C +/-2 °C oscillator, shake 2 h, filter, with a small amount of acetonitrile washing residue several times, combined filtrate, set below 40 °C water bath under reduced pressure to Near dry.

7.2 Purification

Residue with 4.2.1 solvent volume to 10 mL, mix 2 min, centrifuge 5 min, 3000r/min. Take 5.0 mL supernatant over GPC Column at a flow rate of 5 mL/min, eluted with 4.2.1 solvent, discarded the first 100 mL of eluent, collected 100 mL to 165 mL of eluent, 40 °C below the water bath under reduced pressure to near dry, add 8 mL of ethyl acetate dissolved, quantitative transfer to 10 mL centrifuge tube, below 40 °C water Bath with a gentle nitrogen flow to dry, ham samples accurately add 1.0 mL of acetone, aquatic products (pickled products) to accurately add 5.0 mL of acetone, Mixing, gas chromatographic determination.

7.3 Determination

7.3.1 Gas Chromatographic Reference Conditions

A) Column. quartz capillary column, DB-1701, 30 m x 0.53 mm (inner diameter) x 1.0 µm (film thickness), or equivalent;

B) Carrier gas. nitrogen (purity greater than 99.999%); carrier gas flow rate 10 mL/min; tail gas flow rate. 30 mL/min;

75 mL/min, air flow rate. 100 mL/min;

C) Column temperature. initial temperature 150 ° C for 2 min, rise to 270 ° C at 8 ° C/min for 18 min;

D) Inlet temperature. 250 ° C;

E) Detector temperature. 250 ° C;

F) Injection method. no split injection;

G) Injection volume. 2 µL;

H) Opening time. 1.5 min.

7.3.2 Determination and confirmation of chromatography

According to the content of organophosphorus pesticides in the sample, the standard working solution with similar peak area is selected. Standard working solution and sample solution the response value of organophosphorus should be within the linear range of the instrument. Standard working solution and sample volume and other volume interspersed injection determination. In the above chromatographic conditions the chromatogram of the lower standard is shown in Appendix A, Figure A.1.

7.4 Blank experiment

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

10.1 Quantitation limits

Ham samples. dichlorvos, methamidophos, methamphetamine, methyl parathion, malathion, parathion, quinophosphoric acid, Phosphorus is 0.01 mg/kg.

Pickled fish (鲞) samples. dichlorvos, methamidophos, acephate, methyl parathion, malathion, parathion, quinophos, Phosphorus and triazophos were 0.05 mg/kg.

10.2 Recovery rate

The recoveries and precision of the experimental data (in the range of different additive concentrations) are as follows.

Ham samples.

A) dichlorvos.

The recovery was 74% 106% and the precision was 6.4% 11.7% at 0.01 mg/kg, 0.02 mg/kg and 0.1 mg/kg.

B) methamidophos.

The recovery was 74.5% 106% and the precision was 9.6% 11.1% at 0.01 mg/kg, 0.02 mg/kg and 0.1 mg/kg.

C) acephate.

The recoveries were 74% 106% and the precision of 10.9% 11.7% at 0.01 mg/kg, 0.02 mg/kg and 0.1 mg/kg.

D) methyl parathion.

The recoveries were 74% 103% at 0.01 mg/kg, 0.02 mg/kg and 0.1 mg/kg. , Precision 8.6% 11.5% E) malathion.

The recoveries were 72% 104% and the precision of 7.4% 10.9% at 0.01 mg/kg, 0.02 mg/kg and 0.1 mg/kg.

F) Parathion.

The recovery was 71% 105% and the precision was 6.5% 13.1% at 0.01 mg/kg, 0.02 mg/kg and 0.1 mg/kg.

G) quetiophosphoric acid.

The recovery was 78% 105% and the precision was 8.0% 9.5% at 0.01 mg/kg, 0.02 mg/kg and 0.1 mg/kg.

H) Pomperide.

The recovery was 79% 105% and the precision was 7.5% 9.2% at 0.01 mg/kg, 0.02 mg/kg and 0.1 mg/kg.

I) triazophos.

The recoveries were 78% 105% and the precision of 7.8% 9.5% at 0.01 mg/kg, 0.02 mg/kg and 0.1 mg/kg.

Aquatic products (pickled products) samples.

A) dichlorvos.

The recovery was 72% 103% and the precision was 9.8% 11.0% at the concentration of 0.05 mg/kg, 0.1 mg/kg and 0.5 mg/kg.

B) methamidophos.

The recovery was 78% 108% at the concentration of 0.05 mg/kg, 0.1 mg/kg and 0.5 mg/kg, and the precision was 7.0% 9.4% C) acephate.

The recovery was 70% 104% at the concentration of 0.05 mg/kg, 0.1 mg/kg and 0.5 mg/kg, and the precision was 9.0% 9.8% D) methyl parathion.

The recovery was 82% at 0.05 mg/kg, 0.1 mg/kg and 0.5 mg/kg, and the precision was 7.3% 10.1% E) malathion.

The recoveries were 78% 104%, and the precision was 8.4% 9.2% at the concentration of 0.05 mg/kg, 0.1 mg/kg and 0.5 mg /F) Parathion.

The recoveries were 80% 109% at the concentration of 0.05 mg/kg, 0.1 mg/kg and 0.5 mg/kg, and the precision was 7.2% 11.3% G) quetiophosphoric acid.

The recoveries were 74% 104% at the concentration of 0.05 mg/kg, 0.1 mg/kg and 0.5 mg/kg, and the precision was 9.6% 11.4% H) Pomperide.

The recovery was 72% 105% at the concentration of 0.05 mg/kg, 0.1 mg/kg and 0.5 mg/kg, and the precision was 9.6% 11.2% I) triazophos.

The recovery was 79% 105% at the concentration of 0.05 mg/kg, 0.1 mg/kg and 0.5 mg/kg, and the precision was 7.4% 8.2% Appendix A (Informative) Standard chromatogram 1 - dichlorvos (2.4 min) 2 - methamidophos (3.3 min) 3 - acephate (5.9 min) 4 - methyl parathion (10.4 min) 5 - malathion (10.7 min) 6 - parathion (11.3 min) 7 - quinophos (11.7 min) 8 - Mopapine (12.6 min) 9 - triazophos (14.9 min)

Figure A.1 Gas chromatograms of 9 organophosphorus standards

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