GB/T 2795-1981 Test method for 666 and DDT residues in frozen rabbit meat for export
Some standard content:
National Standard of the People's Republic of China
Test Method for Residues of BHC and DDT in Frozen Rabbit Meat for Export
This standard is applicable to the determination of BHC and DDT residues in frozen rabbit meat. 1. Sampling
GB 2795 - B1
1.1 Quantity: Each inspection batch shall not exceed 25,000 cartons. Representative samples shall be drawn according to the following proportions. For less than 5,000 cartons, at least 15 cartons shall be drawn:
For less than 10,000 cartons, at least 20 cartons shall be drawn;
For less than 15,000 cartons, at least 25 cartons shall be drawn:
For less than 20,000 cartons, at least 30 cartons shall be drawn;
For less than 25,000 cartons, at least 35 cartons shall be drawn. The sampling weight of each carton shall not be less than 10,500 grams.
1.2 Sample preparation: Cut the rabbit with bones in half along the vertebral column and remove the bones from half of it. Put all the edible parts into the meat grinder and grind them at least twice. Mix them thoroughly and then use the quartering method to reduce them into 1 cubic meter. The rabbit meat without bones can be directly minced and divided and put into a clear container as a laboratory sample. The laboratory sample must be sealed immediately and labeled with the product name, date, stack position, inspection number, application unit, and sampler.
Note that when taking out the first sample and all subsequent operations, care must be taken not to bring any contaminants into the sample or any changes that would make the laboratory sample unable to represent the total sample of this batch.
2. Test method
2.1 Instruments
2.1.1 Gas chromatograph equipped with the following devices: 2.1.1.1 Ion capture detector:
2.1.1.2 Glass column: 2.0 m × 2.5 mm (inner diameter); 2.1.1.3 Column packing: 2.5% OV-17 + 3.3% QF-1 liquid Chrom(sorb WAW-DMCS 80 mesh.
2.1.1.4 Operating conditions
a, Carrier gas flow rate: Nitrogen, 40 ml/min; b. Column source: 192°C,
C, Injection temperature: 230°C; d, Detector temperature: 217°C
2.1.2 Micro-injector: 1 microliter, 10 microliters, 2.1.3 Meat grinder.
2.1.4 All-glass system heavy distillation device.
2.1.5 Rotary evaporator: SZ-3 type.
2.1.6 Anhydrous sodium sulfate column: In a simple funnel with a funnel diameter of 20 mm and a height of 70 mm. The outer diameter of the handle is 8 mm, put glass in the lower part, and put about 15 grams of anhydrous sodium sulfate in the upper part. 2.2 Reagents
GB 2795—81
2.2.1 Distilled water: Take 100 ml of distilled water and extract it with 10 ml of petroleum ether. Under the chromatographic conditions to be used, adjust the instrument and take 5 μl of the extract and inject it into the gas chromatograph. There should be no impurity peaks other than petroleum ether on the chromatogram. 2.2.2 Petroleum ether: Analytical grade, boiling range 60-75°C, take 300 ml and concentrate it to 5 ml in a rotary evaporator. Under the conditions to be used, adjust the instrument and take 5 μl of the concentrate and inject it into the gas chromatograph. On the chromatogram, except for the peak of this solvent, the height of other peaks shall not exceed the peak height equivalent to 2×10-g of internal body·BHC. 2.2.3 Anhydrous sodium sulfate: Analytical grade, calcined at 650°C for 4 hours. 2. 2.42% sodium sulfate aqueous solution.
2.2.5 Concentrated sulfuric acid: analytical grade.
2.2.6 Glacial acetic acid: analytical grade.
2.2.7 Pernitrogen acid: analytical grade.
2.2.8 Internal standard solution (heptafluoride epoxide) and standard pesticide solution: 2.2.8.1 The content of internal standard and standard pesticide is greater than 99%. 2.2.8.2 Weigh 0.0100g of each of heptafluoride, alpha-BHC, beta-BHC, beta-BHC, 1-BHC, 1P-DE, OP-DDT, PP-DLD, and P'DDT standard products, dissolve them with a little extract, transfer them with petroleum ether, and make up to 100ml volumetric flasks. (The concentration of the solution is 1 μg/L) Dissolve them in A and B respectively. Note: If the sample contains heptachlor epoxide, other internal standards can be selected. 2.2.3 Use a pipette to take 1 ml each of alpha-1H66 and alpha-1H86: 2 ml of beta-1H66; 5 liters each of beta-1H66, PP-DDE, OP-DDT, PP-DDD, and PP-DDT from solution A, place each in a 200 ml volumetric flask, and make up to volume with petroleum ether (the concentrations of the solutions are 0.5 μg/ml for alpha-1H66 and beta-1H66; 1.0 μg/ml for beta-1H66, P-DDE, OP-DDT, PP-DDD, and PP-DDT). Dissolve them in solution B respectively. .2.8.4 Prepare 11 application standard solutions of different concentrations: Take 16, 14, 12, 10, 8, 6, 4, 2, 1.6, 0.8, 0.2 ml of 8 solutions B respectively, place them in 11 100 ml volumetric flasks, add 100 ml of heptachlor epoxide to each, and then use right oil ether to make the volume to 100 ml [the concentration of the solution is shown in the table below (ng/μl)]. They are (solution, application standard solution
A-
BHC
Pro-
BHC
BHC
2.3 Operation steps
2.3.1 ExtractionbzxZ.net
GB 2795—81
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Take 25-50g of the minced and mixed laboratory sample, put it into a 250ml conical flask, add 100ml of 1:1 high-fluorine-glacial acetic acid, put a small end bucket on the mouth of the flask, put it in an 80℃ water bath, and shake it from time to time (to prevent the generation of carbon particles, when it is placed in the water bath, it should be shaken continuously for several minutes) until the contents are completely digested. Rinse with 100ml of steamed stuffing water, put it into a separatory funnel, and extract it three times with 100, 50, and 50ml of petroleum ether respectively. Combine the petroleum ether extracts, filter through an anhydrous sodium sulfate column, collect them in another clean separatory funnel, and wash the anhydrous sodium sulfate column with 15ml of petroleum ether three times. 2.3. 2 Purification
Add concentrated sulfuric acid to the extract (the ratio of extract to concentrated sulfuric acid is 10:1), shake gently, let stand to separate, and discard the lower layer. Repeat purification 1 to 2 times, shake for half a minute each time, let stand to separate, and then discard the lower layer. Transfer the petroleum aldehyde solution to another clean separatory funnel, wash 2 to 3 times with 100 ml of sodium sulfate aqueous solution each time, and discard the water layer. Pass through an anhydrous sodium sulfate column, and wash the separatory funnel and anhydrous sodium sulfate column with a little petroleum ether, collect in a stoppered glass bottle (if the pesticide content is too low, it can be reduced to an appropriate volume), add the internal standard epoxy heptane drop in a quantitative manner, shake well, and then perform gas chromatography determination. 2.3.3 Blank test: Perform a blank test under the above conditions. 2.3.4 Traceability
2.3.4.1 Take 5 μl of each C solution for chromatographic determination (peak order: alpha-BHC, C-BHC, beta-BHC, D-BHC, heptachlor epoxide, PP-DDE, OP DDT, PP-DDD, PPDDT) and measure the peak value.
2.3.4.2 Take an appropriate amount of the following purification solution between 0.2 and 10 μl (so that its response value is within the linear range of the detector) and perform chromatographic determination. Select the peak height of the standard pesticide close to the sample peak quotient, and calculate the residue of each pesticide according to the following formula: Pesticide residue (Ppm) = (H/H\) × (C/C) × (H/H,) × (W/W)) Where: H and H\ - sample peak height and standard peak height (mm); Ho - internal standard peak height in sample (mm); C, and C - concentration of pesticide and internal standard in standard solution injected into chromatograph (ng/μl); W - sample weight (g):
W, - weight of internal standard in sample (μg)
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