GB/T 23200-2008Food safety national standard -- Methods for the determination of herbicide residues -- Part 1: Determination of amide herbicides in grain and oilseeds by gas chromatography-mass spectrometry (English PDF)

4.1 Reagents

4.1.1 n-hexane (C6H14). chromatographic purity.

4.1.2 acetonitrile (CH3CN). pure chromatography.

4.1.3 Acetone (CH3COCH3). Chromatographic pure.

4.1.4 ether ((C2H5) 2O). chromatographic purity.

4.1.5 anhydrous sodium sulfate (Na2SO4). 650 ° C burning 4 h, after cooling placed in the dryer in reserve.

4.1.6 Sodium chloride (NaCl). Analytical purity.

4.2 Solution preparation

4.2.1 Sodium chloride solution. 10% (m/v), 100 g of sodium chloride was dissolved in water and diluted to 1000 mL.

4.2.2 extract agent I. acetonitrile by adding a small amount of n-hexane saturation, shake.

4.2.3 extract agent II. n-hexane by adding a small amount of acetonitrile saturation, shake.

4.2.4 N-Hexane - Ethyl Ether (85 15). Take 85 mL of n-hexane and 15 mL of ether and mix well.

4.3 Standards

4.3.1 Chlorpyrifos, Atrazine, Acetochlor, Dimethalchenamine, Alachlor, Nitrazone, Propellaben, Propoxurine, Butachlor, Propane Amine, prednisamine standard (see Appendix A for specific information), purity greater than 98%.

4.4 Standard solution preparation

4.4.1 accurately weighed 25 ± 0.1 mg standard in 50 mL volumetric flask, dissolved with acetone and volume, get the concentration of 500 g/mL Single standard stock solution, the solution in 0 ~ 4 °C can be stored for 3 months. According to the need to use acetone diluted stock solution, prepared into the appropriate concentration of mixed Standard solution, the solution in 0 ~ 4 °C can be stored for 1 month.

4.5 Materials

4.5.1 Florisil Solid Phase Extraction Column. 125 mg, 3 mL, or equivalent. Before use, use 5 mL n-hexane-ether solution and 5 mL N-hexane pre-leaching column at a flow rate of 1 d/sec.

6.1 Preparation of the sample

The samples were scaled to 1 kg by quarter, and the sample was taken according to GB 2763 Appendix A, and all were ground and passed through a 40 mesh sieve.

Uniform, are divided into two, into a clean container, sealed, marked mark.

6.2 Sample storage

Keep the sample below 5 ° C in dark. During sample and sample preparation, it is necessary to prevent contamination of the sample or change in the content of the residue the

7.1 Extraction

Weigh about 10 g (accurate to 0.01 g) sample in 50 mL centrifuge tube, add 10 mL of water and 20 mL of acetone, homogenized 3 min, Centrifuged at 4000 r/min for 4 min, the extract was transferred to 250 mL eggplant flask, the residue in the centrifuge tube was extracted with 30 mL x 2 acetone, the extract is incorporated into an eggplant bottle. The acetone was removed by evaporation under reduced pressure at 38 ° C and the residue (about 10 mL) was transferred to another 50 mL centrifuge tube.

The eggplant was washed with 10 mL of 10% sodium chloride solution and 15 mL of n-hexane, and the washing solution was transferred into a centrifuge tube and shaken for 3 min.

2500 r/min centrifugation 3 min, collecting n-hexane phase. Centrifuge tube in the water phase and then 15 mL x 2 n-hexane extraction, combined with n-hexane phase.

7.2 Liquid - distribution purification

The n-hexane phase was dehydrated by the addition of an appropriate amount of anhydrous sodium sulfate and the n-hexane phase was completely transferred to another 250 mL eggplant vial at 50 ° C Evaporated to dryness. The residue was dissolved in 5 mL of x 2 extract II and transferred to a 50 mL centrifuge tube. Add 10 mL x 3 extract I, mix, stratified, acetonitrile phase transferred to another 50 mL centrifuge tube. Add 10 mL of the extract II, mix, stratified and discarded n-hexane Phase, the acetonitrile phase was transferred to a 100 mL eggplant flask and evaporated to dryness at 50 ° C. The residue was dissolved in 5 mL of n-hexane.

7.3 Solid phase extraction purification

The above n-hexane solution was transferred to a Florisil solid phase extraction column with a liquid column flow rate of 0.5 d/sec, eluting with 15 mL of n-hexane - ether solution was rinsed with eggplant vials and transferred to a column for elution at a flow rate of 1 d/sec. The complete eluate was collected in a quantitative tube at 40 oC, in the nitrogen stream to the near dry, adding n-hexane dissolved residue and fixed to 1.0 mL for GC-MS determination.

7.4 Determination

7.4.1 Gas Chromatographic Reference Conditions

A) Column. HP-1701 MS, 30 m x 0.25 mm (inner diameter) x 0.25 m (film thickness), or equivalent;

B) Carrier gas. helium (purity greater than 99.999%), flow rate. 1.0 mL/min.

C) column temperature conditions. the initial temperature. 70 °C (keep 1 min); 15 °C/min, heating to 160 °C (to maintain 1 min);

2 °C/min, the temperature is raised to.200 °C (keep 2 min); 20 °C/min, the temperature to 280 °C (to keep 8 min).

D) Inlet temperature. 270 ° C.

E) Injection method. splitless injection, 1 min after the opening of the diversion valve, split ratio of 100. 1.

F) Injection volume. 1 µL;

7.4.2 Mass spectrometry reference conditions

A) Ion source temperature. 230 ° C B) Transmission line temperature. 280 ° C C) Ionization mode. EI D) Scanning range. 50 - 400 amu E) Electron multiplier tube voltage. Auto tuning voltage.200 V;

F) Test method. Select ion monitoring.

7.4.3 Determination and confirmation of chromatography

7.4.3.1 Quantitative determination

According to the herbicide content in the sample solution, the standard working solution with similar peak area is selected, the standard working solution and the herbicide the values shall be within the linear range of the instrument detection. Quantitative method of single or multi-point external standard method, the standard working fluid and sample solution should be inserted into the sample set.

7.4.3.2 Qualitative determination

Qualitative determination of the two basis. (1) the measured sample peak and the standard sample peak chromatographic retention time the same; (2) measured samples and standards the relative abundance of the monitored ions of the test sample shall be consistent with the standard sample, and the difference between the two is not greater than ± 10% (EI mode). See Annex A for monitoring ions and quantitation ions for each herbicide.

Under the above chromatographic and mass spectrometric conditions, the effects of toxaphene, atrazine, acetochlor, dimethylphenols, alachlor, dicarbazone, metolachlor, the retention times of propanil, butachlor, propachlor and darior were 11.2 min, 13.2 min, 13.8 min, 14.9 min, 15.3 min, 15.7 min, 15.9 min, 16.9 min, 19.3 min, 20.6 min, 21.9 min. Select the ion chromatogram see Appendix B, Mass Spectrometry See Appendix C for C1 to C4.

7.5 Blank experiment

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

10.1 Quantitation limits

The limit of quantification of toxaphene, atrazine, acetochlor, metolachlor, propachlor, droper, 0.02 mg/kg; alachlor, butachlor limit of quantification of 0.05 mg/kg.

10.2 Recovery rate

10.2.1 Experimental data on concentration and recovery of herbicides in rice.

The recoveries were in the range of 0.02 mg/kg - 2.0 mg/kg, and the recoveries were 90.3% - 94.5%.

The recoveries were 89.8% - 95.5% in the range of 0.02 mg/kg - 2.0 mg/kg.

The recoveries were 84.5% - 93.5% in the range of 0.02 mg/kg - 2.0 mg/kg.

The recoveries were 84.5% - 93.8% in the range of 0.02 mg/kg - 2.0 mg/kg.

The recoveries were 83.7% - 93.9% in the range of 0.05 mg/kg - 2.0 mg/kg.

The recoveries were 88.3% - 95.6% in the range of 0.02 mg/kg - 2.0 mg/kg.

The recoveries were 88.1% - 93.8% in the range of 0.02 mg/kg - 2.0 mg/kg.

The recovery rate was 83.7% - 95.8% in the range of 0.02 mg/kg - 2.0 mg/kg.

The recoveries were 76.8% - 89.5% in the range of 0.05 mg/kg - 2.0 mg/kg.

The recoveries were 86.9% - 97.5% in the range of 0.02 mg/kg - 2.0 mg/kg.

The recoveries were in the range of 0.02 mg/kg - 2.0 mg/kg, and the recoveries were 94.2% - 101.9%.

10.2.2 Experimental data on the concentration and recovery of herbicides in soybean.

The recoveries were in the range of 0.02 mg/kg - 2.0 mg/kg, and the recoveries were 78.1% - 92.0%.

The recoveries were 80.8% - 92.8% in the range of 0.02 mg/kg - 2.0 mg/kg.

The recoveries were 80.8% - 88.6% in the range of 0.02 mg/kg - 2.0 mg/kg.

The recoveries were 78.7% - 90.9% in the range of 0.02 mg/kg - 2.0 mg/kg.

The concentration of alachlor was between 0.05 mg/kg and 2.0 mg/kg, and the recovery was 76.1% - 86.4%.

The recoveries were 81.7% -91.5% in the range of 0.02 mg/kg - 2.0 mg/kg.

The recoveries were 81.6% -90.3% in the range of 0.02 mg/kg - 2.0 mg/kg.

The recovery rate was 82.9% - 92.5% in the range of 0.02 mg/kg - 2.0 mg/kg.

The concentration of butachlor was in the range of 0.05 mg/kg - 2.0 mg/kg, and the recovery was 72.8% - 83.6%.

The recoveries were in the range of 0.02 mg/kg - 2.0 mg/kg, and the recoveries were 86.4% - 92.7%.

The recoveries were in the range of 0.02 mg/kg - 2.0 mg/kg, and the recoveries were 88.4% - 96.0%.

Appendix A

(Informative)

Table A.1 Quantitative ions and monitoring ions for herbicides

* For the quantitative ions, for different mass spectrometry equipment, instrument parameters may be different, should be measured before the mass spectrometry parameters to optimize the best.

Chinese name English name CAS number Molecular formula Molecular monitoring ion, m/z and its relative abundance Chlorpyrifos Propachlor 1918-16-7 C11H14ClNO 211.69 * 120 (100), 176 (37), 196 (10), 211 (8) Atrazine Atrazine 1912-24-9 C8H14ClN5 215.68 *.200 (100), 215 (62), 172 (15), 173 (35) Acetochlor 34256-82-1 C14H20ClNO2 269.80 * 146 (100), 223 (53), 174 (48), 162 (83) Dimethyl grass Dimethenamid 87674-68-8 C12H18ClNO2S 275.79 154 (100), 203 (42), 230 (58), 232 (20) Alachlor 15972-60-8 C14H20ClNO2 269.77 * 160 (100), 188 (93), 237 (24), 269 (6) Oxalcone metribuzin 21087-64-9 C8H14N4OS 214.28 * 198 (100),.199 (19), 144 (14), 214 (4) Isopropyl grass Metolachlor, Acetamide 51218-45-2 C15H22ClNO2 283.79 * 162 (100), 238 (47), 240 (15), 211 (7) Propanil 709-98-8 C9H9Cl2NO 218.08 * 161 (100), 163 (71), 217 (18), 219 (12) Butachlor 23184-66-9 C17H26ClNO2 311.85 * 176 (100), 160 (86), 188 (49), 237 (27) Pretilachlor 51218-49-6 C17H26ClNO2 311.85 162 (100), 202 (38), * 238 (69), 262 (27) Enantiose Napropamide 15299-99-7 C17H21NO2 271.36 72 (100), 100 (39), * 128 (63), 271 (26) Appendix B (Informative) Standard chromatogram

Figure B.1 SIS chromatograms of standard mixtures of amide herbicides (concentrations of 0.1 mg/L)

1. Acetachlor. 11.2 min; 2. Atrazine. 13.2 min; 3. Acetochlor. 13.8 min; 4. Dimethalfen. 14.9 min; 5. Alachlor.

15.3 min; 6. Oxathione. 15.7 min; 7. metolachlor. 15.9 min; 8. propanil. 16.9 min; 9. butachlor. 19.3 min;

10. Propachlor. 20.6 min; 11. Dendrocaline. 21.9 min.

Appendix C

(Informative)

Standard quality spectrum

Figure C.1 SIM spectra of chloroxamine, atrazine and dimethylphenols

Figure C.2 SIM spectra of oxalcone, propanil, acetochlor

Figure C.3 SIM spectra of butachlor, alachlor, and metolachlor

Figure C.4 SIM spectra of glyphosate and prednisone

Diquat

Napropamide

Appendix D

(Normative appendix) Laboratory repeatability requirements

Table D.1 Laboratory repeatability requirements

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

Table E.1 Inter-laboratory reproducibility requirements

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