This standard specifies the determination method for isofenphos-methyl residues in grains, vegetables and oil crops. This standard is applicable to the determination of isofenphos-methyl residues in grains, vegetables and oil crops. The detection limit of this standard is 0.004 mg/kg. The linear range of this standard is 0 μg/mL to 5.0 μg/mL. GB/T 5009.144-2003 Determination of isofenphos-methyl residues in plant foods GB/T5009.144-2003 Standard download decompression password: www.bzxz.net

1CS 67, 040
National Standard of the People's Republic of China
G/T 5009.1442003
Generation GB/T173501993
Determinatiun of isofenphus-methyl residues in vegetablefoods
Issued on August 11, 2003
Ministry of Health of the People's Republic of China
National Standardization Administration of China
Implementation on January 1, 2004
This standard replaces GB/T17330-1993 Determination of isofenphus-methyl residues in foods3. Compared with GB/T17330-1998, the main changes of this standard are as follows: GB/T5009.144-2003 has been revised as follows: The Chinese name of the standard has been changed to Micro-determination of Residues of Formaldehyde in Foods of Natural Origin; and an introduction has been added: “Connected with Part 4 of GB/T20001.4-2001 Rules for the Preparation of Standards. Chemical Analysis Methods”. The structure of the original standard has been revised. This standard is proposed by the Ministry of Health of the People’s Republic of China and is under the jurisdiction of the drafting units of this standard: Guangdong Provincial Food Hygiene and Animal Husbandry Inspection Institute, Zhongshan Medical University Testing Center, and Guanzhong Industrial Biosafety Station of the Ministry of Health. The main drafters of this standard are Huang Wei, Deng Feng, Shang Yanhong, and Qiu Jian. The original standard was first issued in 1988 and this is the first revision. 227 GD/T 5C-09.144--2003
Methyl isothiocyanate is a pesticide that is difficult to detect in my country's agricultural products. It is highly toxic to insects and has been registered as a soil insecticide for the treatment of underground pests. It has been registered in small and medium-sized crops, wild plants, and oil crops in my country. This standard provides a method for the determination of isothiocyanate residues in plant products (grains, oil crops, and oil crops). 223
GB/T5009.144—2003
Determination of methyl isothiocyanate residues in plant products. This standard specifies the method for the determination of methyl isothiocyanate residues in grains and oil crops. This standard is applicable to the determination of methyl isothiocyanate residues in grains, oil crops, and oil crops. The detection limit of this standard is: <1.004 mR/kg
The range of this standard: 3Ag/mL--5.Cg/mL.2 Principle
The flame photometric detector has high sensitivity, selectivity, and is widely used in the determination of organic matter such as ions and phosphorus. The sample is extracted and purified, and then detected by a gas phase flame photometric detector. The peak height (area) of the sample is compared with the peak height (area) of the standard to calculate the corresponding content of the sample.
3 Reagents
3.1 Ethyl acetate: heavy.
3.2 Anhydrous sulfuric acidbzxz.net
3.3 Monoisocyanate
3.4 ​​Activated carbon; After 20 days of decomposition, weigh 20 active substances. Use 3mol/1. Or filter overnight + drain, wash with water until there is no residue, and dry at 120℃ for 10 days. ||t t||3.5 Heat the silica gel at 520℃ for 4h and set aside. Bake for 2h before use at 140%, and add 5% water to reduce the concentration. 3.6 Use a modified European tube and add a small amount of defatted structure, 1g sodium sulfate, 0.7g of charcoal and 4% Florisil, and 1% anhydrous sodium sulfate from bottom to top.
3. Preparation of methyl isoflavone standard solution Take methyl isoflavone standard product (isofenphnnnetlhyl pure base 97%) and prepare it into a 0.1mg/mL standard solution with propane. Prepare 1,2-dione standard solution (5.04g/mL) 4. Apparatus
4.1 Gas chromatograph with flame photometric detector (FPD) 4.2 Electric heater.
4.3 Organometallic centrifuge,
4.4 Centrifuge.
4.5 Stoppered negative flask: 15gmL, 2eCmL5 Analysis steps
5,. 1 Sample preparation
-For vegetable samples, remove the inedible parts and then pass through a tissue sieve to make a slurry. Take edible crops and other samples and pass through a crusher to make a slurry. 5.2 Extraction
5.2.1 Vegetable (including beet, sugarcane) samples Weigh 500mg of sample, accurately 0.001% of the sample, put it in a grinder, add 30)9~103% sodium monohydrate to dehydrate, transfer to a 2503mL three-fruit cone bottle, add 60ml ethyl acetate (based on the sample soaked), stir for 3 minutes, take the upper solution for 3 minutes, blow it with nitrogen or air until it is close to: 22
GB/T 5009.144—2003
5.2.2 Root food sample: weigh about 10g of grain sample, accurate to 0.001g, put it into a 150mL triangular flask, add 4 mL of ethyl acetate, and extract for 311min, transfer the solution to a centrifuge tube, centrifuge for 13min (30001/min), take 20ml of supernatant, and blow it to nearly zero with oxygen or air.
5.2.3 Oil crops (such as peanuts and soybeans); weigh about 10g of oil crops sample, reduce it to 2.001g, put it into a 150mL triangular flask, add 50mL of ethyl acetate and extract for 30min, transfer the solution to a centrifuge tube, centrifuge for 10min (3009t/min), take 25mL of supernatant, and blow it to nearly zero with nitrogen or air. 5.3 Purification
Transfer the reduced sample solution to the column for purification, elute with 1 ml of ethyl acetate, collect the eluent, blow it to nearly dryness with compressed nitrogen or air, make up to 1 mL with acetone, and inject the sample.
5.4 Gas Chromatography Test Conditions
5. 4.1 Glass column
1m×3mm (inner diameter), filled with Chroosorb W (DMCS>8mm) coated with 2X 20V-17 stationary phase, 5.4.2 Gas flow
Nitrogen, 35mL/min;
Hydrogen, 73mL/min;
Gas flow, 100 mL/m1
5. 4.3 Temperature
Chromatographic column: 202:
Inlet, detector: 229.
5 Determination
6.1 Standard curve drawing
Pipette 0.9, 0.2, 0.4, 0.8, 2.5, 5.0 mL of methyl alcohol standard (5.0 Fg/mL) into 5 mL of aliquot, add C to a standard concentration of 0.0.1, 0.2, 0.4, 0.3, 3.6, 1.5 mL/mL, and inject 1 mL into a gas chromatograph. Then, take the peak area as the standard and the methyl alcohol content as the product coordinate to draw a standard curve. 6.2 Sample determination
Pipette 1 mL of sample solution into a gas chromatograph. Compare the peak areas of the sample and the standard peaks and use the external standard method. 7 Calculation of results
The content of isocyanate in the sample shall be calculated using the following formula:
HXEXVXY
In the test:
The content of isocyanate in the sample, in grams per square gram (g/kg): E. The unit of standard concentration of methyl phthalate is micrograms per milliliter (μg/mL) V, — sample injection volume, unit is μL (μL) V — standard sample volume, unit is μL (μL): initial volume, unit is milliliter (mL) H — sample pesticide peak height, unit is mm2 H. standard pesticide peak height, unit is mm27
sample mass, unit is gram (g)
calculation result expression: report the arithmetic mean to two significant figures, 2.31
8 precision
GB/T 5G09. 144—2003
the absolute integral of two independent determinations taken under repeatability conditions shall not be more than 10 times the average. 9
color error
see the avoidance! :
chromatogram
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