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Determination of pesticide residues BHC and DDT using ECD detector
Determination of pesticide residues BHC and DDT using ECD detector
Product details
Determination of Hexachlorocyclohexane and DDT in Food by Gas Chromatography
1、 Principle
After extraction and purification, the levels of hexachlorocyclohexane and DDT in the sample were determined by gas chromatography and compared quantitatively with the standard. The electron capture detector has extremely high sensitivity to compounds with strong negative electrodes, which can be used to detect trace amounts of BHC and DDT separately. Different isomers and metabolites can be simultaneously measured separately. Peak order: solvent α-HCH、β-HCH、γ-HCH、δ-HCH、pp'-DDE、pp'-DDD、op'-DDT、pp'-DDT
2、 Reagent
1 Acetone.
2 n-hexane
3 Petroleum ether boiling range 30 ℃ -60 ℃
4 benzene.
5 sulfuric acid.
6 anhydrous sodium sulfate.
7 sodium sulfate solution (20g/L).
8 Pesticide standard products: Hexachlorocyclohexane (α - HCH, β - HCH, γ - HCH, δ - HCH) purity>99%;
DDT (pp '- DDE, pp' - DDD, 8. op '- DDT, pp' - DDT) purity>99%,
9 Pesticide Standard Stock Solution: Accurately weigh 10 mg of each of α - HCH, β - HCH, γ - HCH, δ - HCH, pp '- DDE, pp' - DDD, 8. op '- DDT, and pp' - DDT, dissolve them in benzene, transfer them to 100 mL volumetric flasks, dilute with benzene to the mark, mix well, with a concentration of 100 mg/L, and store in the refrigerator.
10. Pesticide mixed standard working solution: Measure the above standard stock solutions separately into the same volumetric flask and dilute to the mark with n-hexane. The concentration of α - HCH, β - HCH, γ - HCH, and δ - HCH is 0.005mg/L, while the concentration of BHC and pp '- DDE is 0.01mg/L. The concentration of op' - DDT is 0.05 mg/L, pp '- DDD is 0.02 mg/L, and pp' - DDT is 0.1 mg/L
3、 Instrument and equipment
Gas chromatograph: GC-9860 gas chromatograph with electron capture detector
Gas source: Nitrogen (99.999%)
Data processing system (computer, printer, chromatography workstation)
Rotary evaporator.
N-evaporator.
Homogenizer machine.
Multi purpose oscillator for speed regulation.
centrifuge
Plant sample grinder.
4、 Analysis steps
1. Sample preparation
Grain is made into powder, and its products are made into homogenate; Vegetables, fruits, and their products are homogenized; Egg products are shelled to make a homogenate; After peeling and gluten the meat, cut it into small pieces and make minced meat; Mix fresh milk well and set aside for later use; Mix the cooking oil well and set aside for later use.
2 Extraction steps processing:
2.1 Eggs: Weigh 20g (accurate to 0.01g) of the sample into a 200ml stoppered triangular flask, add 5mL of water (depending on its moisture content, add water to make the total water volume about 20mL. Usually, fresh eggs have a moisture content of about 75%, add 5ml), add 40mL of acetone, shake for 30 minutes, add 6g of sodium chloride, and shake well. Add 30mL of petroleum ether, shake for 30 minutes, and let it stand for layering. Take 35mL of the supernatant and dehydrate it with anhydrous sodium sulfate. Concentrate it to 1ml in a rotary evaporator, dilute it to 5ml with petroleum ether, purify it with 0.5mL of concentrated sulfuric acid, shake for 0.5 min, and centrifuge at 3000 rpm for 15 min. Take the supernatant for GC analysis.
2.2 Plants: Weigh 20g (accurate to 0.01g) of the sample homogenate, add 5mL of water (depending on its moisture content, add water to make the total water volume about 20mL), add 40mL of acetone, shake for 30 minutes, add 6g of sodium chloride, and shake well. Add 30mL of petroleum ether, shake for 30 minutes, and let it stand for layering. Take 35mL of the supernatant and dehydrate it with anhydrous sodium sulfate. Concentrate it to 1ml in a rotary evaporator, dilute it to 5ml with petroleum ether, purify it with 0.5mL of concentrated sulfuric acid, shake for 0.5 min, and centrifuge at 3000 rpm for 15 min. Take the supernatant for GC analysis.
2.3 Soybean oil: Weigh 1g of the sample (accurate to 0.01g). Add 30mL of petroleum ether directly, shake for 30 minutes, and let it stand for stratification. Take 35mL of the supernatant and dehydrate it with anhydrous sodium sulfate. Concentrate it to 1ml in a rotary evaporator, dilute it to 5ml with petroleum ether, purify it with 0.5mL of concentrated sulfuric acid, shake for 0.5 min, and centrifuge at 3000 rpm for 15 min. Take the supernatant for GC analysis.
2.4 Milk: Weigh 20g (accurate to 0.01g) of fresh milk without adding water. Add 40mL of acetone directly, shake for 30 minutes, add 6g of sodium chloride, and shake well. Add 30mL of petroleum ether and shake for 30 minutes to allow for stratification. Take 35mL of the supernatant and dehydrate it with anhydrous sodium sulfate. Concentrate it to 1ml in a rotary evaporator, dilute it to 5ml with petroleum ether, purify it with 0.5mL of concentrated sulfuric acid, shake for 0.5 min, and centrifuge at 3000 rpm for 15 min. Take the supernatant for GC analysis.
2.5 Meat: Weigh 20g (accurate to 0.01g) of the sample homogenate, add 15mL of water (depending on its moisture content, add water to make the total water volume about 20mL), add 40mL of acetone, shake for 30 minutes, add 6g of sodium chloride, and shake well. Add 30mL of petroleum ether and shake for 30 minutes to allow for stratification. Take 35mL of the supernatant and dehydrate it with anhydrous sodium sulfate. Concentrate it to 1ml in a rotary evaporator, dilute it to 5ml with petroleum ether, purify it with 0.5mL of concentrated sulfuric acid, shake for 0.5 min, and centrifuge at 3000 rpm for 15 min. Take the supernatant for GC analysis.
5、 Gas chromatography conditions:
Chromatographic column: Pesticide residue II (30 * 0.32 * 1.0)
Column temperature 230 ℃
Vaporization temperature 280 ℃
ECD detector at 300 ℃
Carrier gas: High purity nitrogen 99.999%
Column front pressure: 0.5Mpa
Tail blowing: 25ml/min
1、 Principle
After extraction and purification, the levels of hexachlorocyclohexane and DDT in the sample were determined by gas chromatography and compared quantitatively with the standard. The electron capture detector has extremely high sensitivity to compounds with strong negative electrodes, which can be used to detect trace amounts of BHC and DDT separately. Different isomers and metabolites can be simultaneously measured separately. Peak order: solvent α-HCH、β-HCH、γ-HCH、δ-HCH、pp'-DDE、pp'-DDD、op'-DDT、pp'-DDT
2、 Reagent
1 Acetone.
2 n-hexane
3 Petroleum ether boiling range 30 ℃ -60 ℃
4 benzene.
5 sulfuric acid.
6 anhydrous sodium sulfate.
7 sodium sulfate solution (20g/L).
8 Pesticide standard products: Hexachlorocyclohexane (α - HCH, β - HCH, γ - HCH, δ - HCH) purity>99%;
DDT (pp '- DDE, pp' - DDD, 8. op '- DDT, pp' - DDT) purity>99%,
9 Pesticide Standard Stock Solution: Accurately weigh 10 mg of each of α - HCH, β - HCH, γ - HCH, δ - HCH, pp '- DDE, pp' - DDD, 8. op '- DDT, and pp' - DDT, dissolve them in benzene, transfer them to 100 mL volumetric flasks, dilute with benzene to the mark, mix well, with a concentration of 100 mg/L, and store in the refrigerator.
10. Pesticide mixed standard working solution: Measure the above standard stock solutions separately into the same volumetric flask and dilute to the mark with n-hexane. The concentration of α - HCH, β - HCH, γ - HCH, and δ - HCH is 0.005mg/L, while the concentration of BHC and pp '- DDE is 0.01mg/L. The concentration of op' - DDT is 0.05 mg/L, pp '- DDD is 0.02 mg/L, and pp' - DDT is 0.1 mg/L
3、 Instrument and equipment
Gas chromatograph: GC-9860 gas chromatograph with electron capture detector
Gas source: Nitrogen (99.999%)
Data processing system (computer, printer, chromatography workstation)
Rotary evaporator.
N-evaporator.
Homogenizer machine.
Multi purpose oscillator for speed regulation.
centrifuge
Plant sample grinder.
4、 Analysis steps
1. Sample preparation
Grain is made into powder, and its products are made into homogenate; Vegetables, fruits, and their products are homogenized; Egg products are shelled to make a homogenate; After peeling and gluten the meat, cut it into small pieces and make minced meat; Mix fresh milk well and set aside for later use; Mix the cooking oil well and set aside for later use.
2 Extraction steps processing:
2.1 Eggs: Weigh 20g (accurate to 0.01g) of the sample into a 200ml stoppered triangular flask, add 5mL of water (depending on its moisture content, add water to make the total water volume about 20mL. Usually, fresh eggs have a moisture content of about 75%, add 5ml), add 40mL of acetone, shake for 30 minutes, add 6g of sodium chloride, and shake well. Add 30mL of petroleum ether, shake for 30 minutes, and let it stand for layering. Take 35mL of the supernatant and dehydrate it with anhydrous sodium sulfate. Concentrate it to 1ml in a rotary evaporator, dilute it to 5ml with petroleum ether, purify it with 0.5mL of concentrated sulfuric acid, shake for 0.5 min, and centrifuge at 3000 rpm for 15 min. Take the supernatant for GC analysis.
2.2 Plants: Weigh 20g (accurate to 0.01g) of the sample homogenate, add 5mL of water (depending on its moisture content, add water to make the total water volume about 20mL), add 40mL of acetone, shake for 30 minutes, add 6g of sodium chloride, and shake well. Add 30mL of petroleum ether, shake for 30 minutes, and let it stand for layering. Take 35mL of the supernatant and dehydrate it with anhydrous sodium sulfate. Concentrate it to 1ml in a rotary evaporator, dilute it to 5ml with petroleum ether, purify it with 0.5mL of concentrated sulfuric acid, shake for 0.5 min, and centrifuge at 3000 rpm for 15 min. Take the supernatant for GC analysis.
2.3 Soybean oil: Weigh 1g of the sample (accurate to 0.01g). Add 30mL of petroleum ether directly, shake for 30 minutes, and let it stand for stratification. Take 35mL of the supernatant and dehydrate it with anhydrous sodium sulfate. Concentrate it to 1ml in a rotary evaporator, dilute it to 5ml with petroleum ether, purify it with 0.5mL of concentrated sulfuric acid, shake for 0.5 min, and centrifuge at 3000 rpm for 15 min. Take the supernatant for GC analysis.
2.4 Milk: Weigh 20g (accurate to 0.01g) of fresh milk without adding water. Add 40mL of acetone directly, shake for 30 minutes, add 6g of sodium chloride, and shake well. Add 30mL of petroleum ether and shake for 30 minutes to allow for stratification. Take 35mL of the supernatant and dehydrate it with anhydrous sodium sulfate. Concentrate it to 1ml in a rotary evaporator, dilute it to 5ml with petroleum ether, purify it with 0.5mL of concentrated sulfuric acid, shake for 0.5 min, and centrifuge at 3000 rpm for 15 min. Take the supernatant for GC analysis.
2.5 Meat: Weigh 20g (accurate to 0.01g) of the sample homogenate, add 15mL of water (depending on its moisture content, add water to make the total water volume about 20mL), add 40mL of acetone, shake for 30 minutes, add 6g of sodium chloride, and shake well. Add 30mL of petroleum ether and shake for 30 minutes to allow for stratification. Take 35mL of the supernatant and dehydrate it with anhydrous sodium sulfate. Concentrate it to 1ml in a rotary evaporator, dilute it to 5ml with petroleum ether, purify it with 0.5mL of concentrated sulfuric acid, shake for 0.5 min, and centrifuge at 3000 rpm for 15 min. Take the supernatant for GC analysis.
5、 Gas chromatography conditions:
Chromatographic column: Pesticide residue II (30 * 0.32 * 1.0)
Column temperature 230 ℃
Vaporization temperature 280 ℃
ECD detector at 300 ℃
Carrier gas: High purity nitrogen 99.999%
Column front pressure: 0.5Mpa
Tail blowing: 25ml/min
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