GB 23200.78-2016Food safety national standard -- Meat and meat products -- Determination of the content of carbamate residues -- Gas chromatographic method (English PDF)

4.1 Reagents

4.1.1 Acetone (C7H6O). Chromatographic purity.

4.1.2 Cyclohexane (C6H12). Chromatographic Purification.

4.1.3 Ethyl acetate (C4H8O2). Chromatographic purity.

4.2 Solution preparation

4.2.1 cyclohexane-ethyl acetate (1 1, volume ratio). take 100 mL of cyclohexane, add 100 mL of ethyl acetate, shake back. The 4.2.2 anhydrous sodium sulfate. 650 °C burning 4 h, stored in a sealed container in reserve.

4.3 Standards

4.3.1 Bareto phosphorus standard (Crotoxyphos, C14H19O6P, CAS. 7700-17-6). purity >= 99%.

4.4 Standard solution preparation

4.4.1 Batch phosphorus standard solution. accurately weighed the appropriate amount of standard phosphorus poisonants, with acetone prepared into a concentration of about 1.0 mg/mL standard reserve Liquid, and then need to use acetone diluted to the appropriate concentration of standard working solution. Standard stock solution in 0 ~ 4 °C refrigerator to save, valid for 12 Month, the standard working fluid in the 0 ~ 4 °C refrigerator to save, valid for 6 months.

6.1 Preparation of the sample

Will take all the samples, shrink out with a representative sample of not less than 500g, the sampling site according to GB 2763 Appendix A, the mashed Machine fully mashed evenly, are divided into two, respectively, into a clean container, sealed, marked mark.

6.2 Sample storage

The sample was stored at -18 ° C or lower. During the operation of the sample preparation, the sample should be prevented from being contaminated or the content of the residue can be changed the

7.1 Extraction

Weigh the sample about 10.0 g (accurate to 0.1 g) in a 50 mL centrifuge tube, add 10 g of anhydrous sodium sulfate, stir with a glass rod and mixed with the sample, then add 20 mL of cyclohexane-ethyl acetate (1 1, volume ratio), homogeneous 2min, 3000r/min centrifugation 3 min, the upper organic phase was passed through an anhydrous sodium sulfate column and collected in a 100 mL concentration flask. The residue was washed with 40 mL of cyclohexane-ethyl acetate (11, Volume ratio) The extracts were extracted twice in the same manner as described above, concentrated to about 5 mL at 40 ° C, and the extract was transferred to a 10 mL scale test and the mixture was washed three times with 3 mL of cyclohexane-ethyl acetate (1 1, by volume), and the washing solution was combined in a graduated tube.

Cyclohexane-ethyl acetate (1 1, volume ratio) to 10 mL, over 0.45 m filter, to be gel permeation chromatography (GPC) purification.

7.2 Purification

7.2.1 Gel permeation chromatography (GPC) purification

7.2.2 Gel Permeation Chromatographic Conditions

A) Gel purification column. length 400 mm, inner diameter 25 mm, Bio Beads S-X3, or equivalent;

B) mobile phase. cyclohexane-ethyl acetate (1 1, volume ratio);

C) Flow rate. 5.0 mL/min;

D) sample dosing loop. 5.0 mL;

E) Pre-leaching time. 17 min;

F) Gel permeation chromatograph equilibration time. 5 min;

Collection time. 17 ~ 30 min.

7.2.3 Gel Permeation Chromatography Purification steps

10 mL of the purified liquid was purged according to the conditions specified in 7.2.2, and the collected components were concentrated at room temperature and the mixture was concentrated.

1.0mL acetone dissolved in volume, gas chromatographic determination.

7.3 Determination

7.3.1 Gas Chromatographic Reference Conditions

A) Column. HP-5, column length 30 m, inner diameter 250 µm, film thickness 0.25 µm, or equivalent;

B) Carrier gas. nitrogen, purity >=99.99%, 1.5mL/min;

C) tail gas. nitrogen, purity >= 99.99%, 60mL/min;

D) hydrogen. 75 mL/min;

E) air. 100 mL/min;

F) column temperature. initial temperature of 180 °C, keep 1 min, at 10 °C/min rate increased to 280 °C, keep 5min;

G) Inlet temperature. 250 ° C;

H) Detector temperature..200 ° C;

I) Injection volume. 1 µL;

J) Injection method. no split injection.

7.3.2 Chromatographic determination

According to the sample of phosphorus poisonous phosphorus content, select the peak area and sample solution similar to the standard working solution. Standard working solution and sample solution of poisonous phosphorus the response value should be within the linear range of the instrument detection. Standard working fluid and sample solution should be equal to the volume of plug-in injection determination. Under the above chromatographic conditions, the retention time of the drug is about 6.67 min. The gas chromatogram of the standard substance of the toxic substance is shown in Appendix A and quantified by the external standard method.

7.4 Gas Chromatography - Mass Spectrum Confirmation

7.4.1 Gas Chromatography - Mass Spectrometry Reference Conditions

A) Column. Rtx-5MS, column length 30 m, inner diameter 250 µm, film thickness 0.25 µm, or equivalent;

B) Carrier gas. helium, purity >=99.99%, 1.5mL/min;

C) Column temperature.

D) the program temperature. the initial temperature of 180 °C, keep 1 min, at 10 °C/min rate increased to 280 °C, keep 5 min;

E) Inlet temperature. 250 ° C;

F) chromatographic - mass spectrometer interface temperature. 280 ° C;

G) Injection volume. 1 µL;

H) injection method. no shunt, 1min after the opening valve;

I) ionization energy. 70 eV;

J) ionization mode. EI;

K) Measurement method. ion monitoring mode;

L) monitoring of ions (m/z). 193,166,127,105;

M) solvent delay. 3 min.

7.4.2 Confirmation of mass spectrometry

If the sample solution and the standard solution of the gas chromatogram, in the same retention time there is a peak, you can confirm it by mass spectrometry. Benchmarking the quasi-solution and sample solution were determined according to the conditions specified in 7.4.1.

7.5 Blank experiment

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

10.1 Quantitation limits

The limit of quantification of this method is 0.01 mg/kg.

10.2 Recovery rate

When the levels were 0.01 mg/kg, 0.05 mg/kg, 0.1 mg/kg, the recovery rates for the addition of carbamate were given in Appendix B.

Appendix A

(Informative)

Standard Gas Chromatography

Figure A.1 Gas Chromatogram of Batch Phosphorus Standard

Appendix B

(Informative)

This method adds concentration and recovery range

Table B.1 This method adds concentration and recovery range

Sample name Add concentration (mg/kg) Recovery rate range (%) Variation coefficient (%) pork 0.010 73.0 ~ 96.0 9.02 0.050 79.4 ~ 98.8 7.22 0.100 89.5 ~ 101.3 4.11 sausage 0.010 71.0 to 86.0 7.02 0.050 81.0 ~ 94.0 4.89 0.100 84.5 ~ 103.3 7.23 Canned luncheon meat 0.010 71.0 to 101.0 10.47 0.050 74.6 ~ 99.5 9.65 0.100 75.6 ~ 94.6 6.96 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