GB 23200.70-2016Food safety national standard -- Determination of Trifluorocarbazone Residue in Food by Liquid Chromatography-mass spectrometry / Mass Spectrometry (English PDF)

4.1 Reagents

4.1.1 acetonitrile (CH3CN). high performance liquid chromatography grade.

4.1.2 Methanol (CH3OH). High performance liquid chromatography grade.

4.1.3 Formic acid (HCOOH).

4.1.4 Sodium chloride (NaCl).

4.1.5 anhydrous sodium sulfate (Na2SO4). before burning at 650 °C for 4 hours, stored in a dryer, cooling and standby.

4.2 Solution preparation

4.2.1 Formic acid - acetonitrile solution. 0.5 mL of formic acid was added to 500 mL of acetonitrile and shaken for standby.

4.2.2 Formic acid - aqueous solution. 1.0 mL of formic acid was added to 1000 mL of water and shaken.

4.2.3 Constant solution. (formic acid - aqueous solution) - acetonitrile (19, V/V)

4.2.4 n-Hexane. add appropriate amount of acetonitrile and shake well before use.

4.3 Standards

4.3.1 Reference substance. trifluorocarbamate (CAS. 50594-66-6), purity >=99%.

4.4 Standard solution preparation

4.4.1 Standard stock solution. accurately weighed the appropriate standard (accurate to 0.1 mg), dissolved in methanol, prepared into a concentration of 100 µg/mL of the standard stock solution, -18 °C below the frozen light preservation, valid for 3 months.

4.4.2 standard intermediate solution. accurate removal of 1 mL standard stock solution in 10 mL volumetric flask, with constant volume solution to the volume, prepared into Concentration of 10 µg/mL standard intermediate solution, 0 °C ~ 4 °C cold storage, valid for 1 month.

4.5 Materials

4.5.1 solid phase extraction column. carbon eighteen column, 3 mL, or equivalent, before use with 10 mL formic acid - acetonitrile solution pre-leaching.

4.5.2 Microporous membrane. 0.20 µm, organic phase type.

4.5.3 Nitrogen. Purity >=99.999%.

6.1 Soy, rice and brown rice samples

500 g of the sample was taken and pulverized with a pulverizer and passed through a 20 mesh sample. Mix well and fit into a clean container Inside, sealed and identified, in 0 °C ~ 4 °C dark preservation.

6.2 Soybeans, apples and pork

500 g of the sample was taken, crushed and mixed evenly with a pulverizer, filled in a clean container, sealed and identified, and cooled at -18 ° C Frozen light preservation.

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

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

7.1 Extraction

Weigh the sample 5 g (accurate to 0.01 g) and place it in a 50 mL stoppered plastic centrifuge tube. For soy, rice and brown rice samples, join 10 mL of water, vortex mixed for 30 min after adding 20 mL of acetonitrile; for soybeans, apples and pork samples, add 20 mL Acetonitrile. After 30 min of shaking and centrifuged at 4 000 r/min for 3 min, the supernatant was transferred to another 50 mL stoppered plastic centrifuge tube, the residue was extracted once again with 15 mL of acetonitrile and the supernatant was combined. To the supernatant was added 3 g of sodium chloride and the mixture was vortexed at 4 000 r/min After centrifugation for 1 min, the upper layer solution was transferred to a separatory funnel. Then add 15 mL of acetonitrile repeated extraction time, combined with the upper solution, to be purified.

7.2 Purification

7.2.1 Liquid-liquid distribution purification

20 mL of n-hexane was added to the solution to be purified and allowed to stand for 5 min. The lower layer of the solution was passed through an anhydrous sodium sulfate funnel and collected Shrink bottle. In 40 °C below the water bath spin concentrated to near dry, and then dry with nitrogen. The residue was dissolved in 1 mL of formic acid-acetonitrile solution.

7.2.2 Solid phase extraction purification

The effluent was collected while the formic acid-acetonitrile solution was transferred to the ENVI-18 solid phase extraction column. And then with 5 mL of formic acid-acetonitrile solution Elute all the effluent. The whole solid phase extraction purification process controls the flow rate not to exceed 2 mL/min. The effluent is used below 40 ° C Nitrogen blown dry. The residue was dissolved in 1.0 mL constant solution and the mixture was vortexed and passed through a 0.2 µm microporous membrane for instrumentation.

7.2.3 Preparation of matrix standard working solution

Weigh five blank samples and follow the 7.1 steps. In step 7.2, a volume of standard solution is removed and added to each Purified effluent by solid phase extraction, the rest of the steps with 7.2. Matrix standard working solution should be used with the current distribution.

7.3 Determination

7.3.1 Liquid Chromatographic Reference Conditions

A) Column. C18,150 mm × 2.1 mm (id), 5 µm, or equivalent.

B) Column temperature. 40 ° C.

C) Flow rate. 0.2 mL/min.

D) Injection volume. 10 µL.

E) Mobile phase. acetonitrile. formic acid - water (%) (90 10, volume ratio)

7.3.2 Mass spectrometry reference conditions

See Table A.1 and Table A.2.

7.3.3 Qualitative determination

The sample and matrix standard solutions were determined according to the above conditions if the mass retention time of the sample was compared with that of the mixed matrix standard solution the relative abundance of the qualitative ion pair is consistent with the relative abundance of the matrix standard solution corresponding to the concentration, and the relative abundance deviation does not exceed the table 1, you can determine the existence of the corresponding sample in the sample.

Table 1 Maximum allowable deviation of relative ion abundance at qualitative determination

Relative abundance (base) 50% 20% to 50% 10% to 20% <=10% Allowable relative deviation ± 20% ± 25% ± 30% ± 50%

7.3.4 Quantitative determination

According to the external standard method for quantitative calculation. According to the concentration from small to large order, followed by analysis of matrix standard working solution, the concentration and peak Product of the work curve. The response value of the analyte in the sample solution should be within the working curve. Under the above liquid chromatography-mass/mass spectrometry conditions, the retention time of the triflate was 2.3 min. Mass Spectrometer/Mass Spectrometry Multi-Reaction Monitoring (MRM) Chromatogram Particle Mass Spectrometry See Appendix B.

10.1 Quantitation limits

The quantification limit of the method is 352 mg/kg.

10.2 Recovery rate

When the levels were 0.002 mg/kg, 0.004 mg/kg, 0.02 mg/kg, 0.1 mg/kg, the addition recovery of trifluorocarbamate See Appendix C.

Appendix A

(Informative)

Table A.1 Mass spectrometry conditions

Ion source ESI-

Capillary voltage of 4.0 kV Drying gas temperature 350 °C the atomizer pressure is 40 psi Dry gas flow rate nitrogen, flow rate 8 L/min Collision gas nitrogen Scanning mode Anion scanning Monitoring Multiple Response Monitoring (MRM)

Table A.2 Multi-reaction monitoring conditions

Chinese name ion ion ion residence time fragmentation voltage collision energy Trifluorocarbamate 360.1 316.1 * 0.20 s 80 V 3 eV 286.1 0.20 s 80 V 10 eV Note. Add "*" ions for quantitation.

1) Non-commercial statement. Appendix A The parameters listed in Table A are done on the Agilent 6410 QQQ mass spectrometer. The test instrument model is listed here only for Provide reference, does not involve commercial purposes, to encourage standard users to try to use different manufacturers or models of equipment.

Appendix B

(Informative)

Multi - reaction monitoring mass chromatogram

Figure B.1 Standard Multi-Reaction Monitoring Quality Chromatogram

Appendix C

(Informative)

Add concentration and recovery range

Table C.1 Add concentration and recovery range

sample name

Add concentration

Mg/kg

Recovery rate range

Soybeans

0.002 81.1 to 91.8

0.004 80.4 to 97.3

0.02 81.4 to 97.1

0.1 84.4 ~ 98.0

Rice

0.002 80.1 to 94.2

0.004 81.0 to 97.5

0.02 81.0 to 95.3

0.1 84.1 to 97.3

brown rice

0.002 82.8 ~ 94.2

0.004 80.1 to 97.3

0.02 80.1 to 96.7

0.1 85.3 ~ 97.1

Soybeans

0.002 84.3 ~ 92.7

0.004 80.5 to 94.7

0.02 81.8 ~ 94.9

0.1 86.2 to 96.6

apple

0.002 80.7 to 95.0

0.004 80.7 to 96.5

0.02 81.8 to 96.2

0.1 86.1 to 96.1

pork

0.002 80.7 to 94.6

0.004 84.6 to 97.0

0.02 84.6 ~ 96.0

0.1 85.9 to 97.5

Appendix D

(Normative appendix) Laboratory repeatability requirements 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