Some standard content:
Sensory index
People's Republic of China
National standard
Food hygiene standard
It should have the color and smell of normal food, and should not be moldy or deteriorated. Physical and chemical indexbZxz.net
Physical and chemical indexes are shown in the following table:
Phosphide (measured in PH) (measured in raw grain)Cyanide (measured in HCN)
Chloropicrin (measured in raw grain)
Carbon disulfide (measured in raw grain)
(measured in raw grain)
Arsenic (measured in As) (measured in raw grain)
Mercury (measured in Hg)
(measured in finished grain)
Hexachlorobenzene (measured in finished grain) 3.1 Gas chromatography method 3.2 Reagents The reagents used are generally analytical reagents. Petroleum ether; 30～60℃. 3.2.2 Ether. GB 2715—81 Replace GB 1-77 (mg/kg) According to GB2761-81, silicon magnesium adsorbent: 60～100 mesh. Take 100g and heat it in a high-temperature furnace at 300℃ for 120min. After cooling naturally in the furnace, 3.2.3
Take out and add 5ml of water, shake vigorously until completely mixed, and immediately load the column for use. 3.2.4 Anhydrous sodium sulfate.
3.2.5 Eluent: petroleum ether: ether = 96:4. State Administration of Standards
Ministry of Health of the People's Republic of China
Implemented on June 1, 1982
Drafted by the Institute of Food Hygiene, Chinese Academy of Medical Sciences 17
GB 2715-81
3.2.6 Standard solution: Weigh appropriate amounts of organochlorine standards of heptachlor, aldrin, and dieldrin, prepare a stock solution with benzene, and store in a refrigerator. 3.2.7 Standard working solution: Before use, dilute with petroleum ether to make working solution, the concentration of which is 0.1 μg per ml for each of heptachlor, aldrin, dieldrin, and β666, 0.2 ug per ml for each of α-666, -666, and op-DDE, and 0.3 μg per ml for each of pp-DDE, ppDDD, op-DDT, and Pp-DDT. 3.3 Instruments
8.3.1 Gas chromatograph with electron capture detector. 3.3.2 Small pulverizer.
3.3.3 Electric oscillator.
3.3.4 Electric water bath.
3.3.5 Vacuum pump.
All-glass concentrator.
3.3.7 Vertical melting funnel No. 4.
3.3.8 Column chromatography tube: 1.5 cm in diameter and 40 cm in length. 3.3.9 Preparation of chromatographic column: Weigh 20g of support Chromosorb WAWDMCS 60~80 mesh, 0.6g and 0.4g of stationary liquid QF-1, then rinse the stationary liquid with 100ml of chloroform: n-butanol = 1:1 mixture in a round-bottom flask, heat to reflux in a 98℃ water bath to completely dissolve it (3~4h), then pour the support in, heat to reflux for a while (shake the round-bottom flask while heating to completely mix the support and stationary liquid), then pour into a large glass flat blood, dry under an infrared lamp, and after loading, age at 250℃ with nitrogen for 27h.
3.4 Operation method
3.4.1 Extraction: Weigh 50g of sample that has passed through a 20-mesh sieve after being crushed, place it in a 500ml conical flask, add 150ml of petroleum ether, shake it on an electric shaker for 60min, remove it, and after precipitation, pour the supernatant into a vertical melting funnel, filter it into a full glass concentrator under reduced pressure, then add 100ml of petroleum ether to the residue and shake it for 30min, filter it under reduced pressure, and then wash the conical flask and the residue in the flask with 30ml of petroleum ether three times, collect all the filtrate in a 50℃ electric water bath, and concentrate it to 5ml under vacuum. 3.4.2 Purification: Weigh 20g of silicon-magnesium type adsorbent in a small beaker, add about 20ml of petroleum ether, gently stir it with a glass rod until it is completely wet, and then wait for column loading. Place a little absorbent cotton at the lower end of the chromatography column, pour a little petroleum ether to moisten it and expel the bubbles in the gaps, use a small glass funnel to evenly fill the silica-magnesium adsorbent, then add 4g of anhydrous sodium sulfate on the upper layer, release the petroleum ether until only a thin layer is left on the upper part of the anhydrous sodium sulfate, add the sample concentrate into the purification column at a flow rate of about 4ml per minute, and when only a thin layer of the sample is left, add 300ml of eluent in batches, elute at a flow rate of about 4ml per minute, collect all the eluent in a full-glass concentrator, reduce the pressure to 10ml in a 50℃ water bath, and take 2μl for injection.
3.4.3 Chromatographic conditions
3.4.3.1Ni63 electron capture detector
Vaporization chamber temperature: 250℃,
Chromatographic column temperature: 218℃,
Detector temperature: 250℃,
Carrier gas (nitrogen) flow rate: 70ml/min
Pulse power supply: width 8us, period 100μs, voltage: 30V.
3.4.8.2Chromatographic column: a glass column with an inner diameter of 3mm and a length of 2m, filled with 60-80 mesh Chromosorb W AWDMCS coated with 2% OV1 and 3% QF-1.
3.4.3.3Measurement and calculation
The linear range of the electron capture detector is narrow. In order to facilitate quantification, the sample injection volume is selected to fit the linear range of each group. According to the existence form of heptachlor, aldrin, dieldrin, hexachloride and DDT in the sample, the standard curve of each component is prepared accordingly, and the content (X) in the sample is calculated as follows.
GB 2715--81
A × 1000
×1000
Wherein: the content of heptachlor, aldrin, dieldrin, hexachloride, DDT and its isomers in the sample, mname/kg, the content of heptachlor, aldrin, dieldrin, hexachloride and DDT in the sample solution, nname, the volume of sample purification solution, US
the injection volume of sample solution, 1
the mass of sample, g.
Amendment No. 1 of GB27151981 "Standards for Food Hygiene" This amendment has been approved by the Ministry of Health in Document No. 73 of Weifangzi [1986] on October 14, 1986, and will be implemented on October 14, 1986.
In the table of physical and chemical indicators, the residual amounts of heptachlor, wormwood and benzyl alcohol (all calculated on the basis of raw grain) are added, and their values are all less than or equal to 0.02 mg/kg. 19
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