GB 23200.48-2016Food safety national standard -- Determination of residual residues in food by gas chromatography-mass spectrometry (English PDF)

4.1 Reagents

4.1.1 Acetone (CH3COCH3, CAS. 67-64-1). Chromatographic Purification.

4.1.2 Dichloromethane (CH2Cl2, CAS. 75-09-2). Chromatographic pure.

4.1.3 Cyclohexane (C6H12, CAS. 110-82-7). Chromatographic purity.

4.1.4 Ethyl acetate (C4H8O2, CAS. 141-78-6). Chromatographic pure.

4.1.5 n-Hexane (C6H14, CAS. 110-54-3). Chromatographic pure.

4.1.6 anhydrous sodium sulfate (Na2SO4, CAS. 15124-09-1). 650 °C burning 4 h, stored in a sealed container in reserve.

4.2 Solution preparation

4.2.1 sodium sulfate aqueous solution (20 g/L). take 20g anhydrous sodium sulfate, water volume to 1000mL, shake back standby.

4.3 Standards

4.3.1 Wild Yandeng Standard Substance. See Appendix A.

4.4 Standard solution preparation

4.4.1 wild wild dry standard stock solution. accurately weighed the right amount of wild Yan dry standard material, with acetone prepared into a concentration of 100 g/mL Standard stock solution, the standard reserve solution away from 0 °C ~ 4 °C preservation, shelf life of 6 months.

4.4.2 wild Yan dry standard working solution. According to the testing requirements, respectively, the above standard reserve solution in the volumetric flask, diluted with acetone to the standard preparation of the appropriate concentration of the standard working solution, the standard working solution away from 0 °C ~ 4 °C preservation, shelf life of one month.

4.5 Materials

4.5.1 Florisil Solid phase extraction column. 1.0 g, or equivalent.

5.9 Filtration. 0.45 m

5.10 oscillator.

6.1 Preparation of the sample

6.1.1 Grain

The sample was shrunk to 1 kg by quarter, homogenized with an attritor and passed through a 2.0 mm round hole screen. Mix, are divided into two as the sample is packed in a clean vial, sealed and marked.

6.1.2 Meat and meat products

A sample of about 1 kg was taken from all the samples taken and crushed evenly through the crusher and divided into two portions Clean the container as a sample. Sealed and marked.

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

6.2 Sample storage

Grains and oilseeds are stored at 0-4 ° C; meat and meat samples are cryopreserved at -18 ° C or lower. In the sampling and sample operation in the course of the process, the sample should be prevented from being contaminated or the residue content changes.

7.1 Extraction

Weigh the sample about 20 g (accurate to 0.1 g) in a 250 mL stoppered flask, add 100 mL of water - acetone (14), shake Extraction for 30 min, the extract was filtered in 250 mL concentrated bottle. Residue and then 50 mL of acetone repeated extraction time, combined filtrate, and concentrated in a water bath at 40 ° C to about 20 mL.

The concentrated extract was transferred to a 250 mL separatory funnel, 150 mL of sodium sulfate aqueous solution and 50 mL of dichloromethane were added, shaking 3 Min, and the layers were separated and the dichloromethane phase was collected. The aqueous phase was extracted twice with 2 x 50 mL of methylene chloride and the dichloromethane phases were combined.

Dehydrated by anhydrous sodium sulfate column, collected in 250 mL concentrated flask, concentrated in a 40 ° C water bath to near dry, add 5 mL of cyclohexane -Ethyl acetate (1 1) to dissolve the residue and filter with a 0.45 m filter to be purified.

7.2 Purification

7.2.1 Gel Chromatography (GPC)

7.2.1.1 Gel chromatographic conditions

A) Purification column. 700 mm × 25 mm, Bio Beads S-X3, or equivalent.

B) Mobile phase. cyclohexane-ethyl acetate (1 1).

C) Flow rate. 5.0 mL/min.

D) Sample dosing ring. 5.0 mL.

E) Pre-elution volume. 50 mL.

F) Elution volume. 150 mL.

G) Collection volume. 75 mL to 10.5 mL.

7.2.1.2 Gel Chromatographic Purification Procedure

The 5 mL of the purified liquid was purified under the conditions specified in 7.2.1.1, and the collected fractions in the combined fraction collector were mixed in 50 mL of concentrated in the 40 ° C water bath spin concentrated to near dry, add 2 mL of n-hexane to dissolve the residue, to be purified.

7.2.2 Solid Phase Extraction Purification (SPE)

The Florisil solid phase extraction column was pre-eluted with 5 mL of n-hexane and the sample was poured into the column and then treated with 8 mL N-hexane-ethyl acetate (4 1). The whole eluate was collected in a 50 mL concentration flask and concentrated in a 40 ° C water bath dry. Dissolved in acetone and set to 2 mL, gas chromatography - mass spectrometry and confirmed.

7.3 Determination

7.3.1 Gas Chromatography - Mass Spectrometry Reference Conditions

A) Column. DB-5 MS quartz capillary column, 30 m × 0.25 mm (id), film thickness 0.25 m, or equivalent.

B) Column temperature. 50 ° C (for 2 min) 20 ° C/min 180 ° C (for 1 min) 10 ° C/min 270 ° C 10 min).

C) Inlet temperature. 280 ° C.

D) chromatographic - mass spectrometer interface temperature. 270 ° C.

E) Carrier gas. helium, purity >=99.999%, flow rate 1.2 mL/min.

F) Injection volume. 1 µL.

G) Injection method. no split injection, 1.5 min after the opening valve.

H) ionization mode. EI.

I) Ionization energy. 70 eV.

J) Measurement method. Select the ion monitoring mode.

K) Monitoring ions (m/z). See Appendix A.

L) solvent delay. 5 min.

7.3.2 Determination and confirmation of chromatography

According to the sample in the wild Yan dry content, selected peak area similar to the standard working solution, the standard working solution and sample solution the response value of the standard working solution and the sample solution should be within the linear range of the instrument detection.

Under the same experimental conditions, the mass retention time of the material to be tested in the sample solution was the same as that of the standard working solution and the background the selected ions in the sample mass chromatogram appear after comparison with the abundance of the selected ions and the abundance of the corresponding ions Within the allowable range (see Table 1 for the permissible range), it is determined that there is a corresponding analyte in the sample. In the above chromatographic conditions, wild Yan dry (M/z) abundance ratio is shown in Appendix A. Gas Chromatography - Mass Spectrometry Ion Chromatogram and the spectra are given in Appendix B, B.1 and Appendix C, C.1.

Table 1 Maximum allowable error for relative ion abundance using gas chromatography-mass spectrometry

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

7.4 Blank test

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

10.1 Quantitation limits

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

10.2 Recovery rate

When the levels were 0.010 mg/kg, 0.050 mg/kg and 0.200 mg/kg, the addition recovery See Appendix D.

Appendix A

(Informative)

Wild leafy CAS number, retention time and monitoring ion abundance ratio

Table A.1 CASE CASE, retention time and monitoring ion abundance ratio table

No. Chinese name English name CAS number Molecular formula Molecular weight retention time Min Monitor the ion abundance ratio

1 Dryer Drying Difenzoquat 43222-48-6 C18H20N2O4S 360.43 15.80 189 (6), 233 (23), 234 (100), 235 (18) Note. "*" mark ions as quantitative ions Appendix B (Informative) Gas Chromatography - Mass Spectrometry Ion Chromatography

Figure B.1 Gas Chromatography-Mass Spectrometry Ion Chromatogram of Wild Yandeng Substances

Min

Appendix C

(Informative)

Gas Chromatography - Mass Spectrometry of Wild

Figure C.1 Gas Chromatography-Mass Spectrometry for Wild Goap Standard

Appendix D

(Informative)

The recovery rate of wild leaves in different matrices

Table D.1 Recovery rates of wild leaves in different substrates

NO pesticide name

Sample matrix

Wheat corn pork beef 1 wild Yan dry 89.0% ~ 94.9% 88.0% ~ 88.3% 86.5% ~ 95.0% 92.4% ~ 93.5% Appendix E (Normative appendix) Laboratory repeatability requirements

Table E.1 Laboratory repeatability requirements

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

Table F.1 Inter-laboratory reproducibility requirements

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