Principle

The sample is extracted by acetone n-hexane (1+8) ultrasound, and the extract is concentrated to volume. It is then measured using a gas chromatograph equipped with an electron capture detector (GC-ECD) and quantified using an external standard method, or determined and confirmed using gas chromatography-mass spectrometry (GC-MS) and quantified using an external standard method

Reagents and Materials

Unless otherwise specified, all reagents used should be analytical pure.

. 3.1 Acetone; Residual level 3.2 n-hexane: residual grade. 3.3 Benzene: residual grade 3.4 Anhydrous sodium sulfate: Burn at 650 ℃ for 3 hours, cool and store in a dryer for future use. 3.5 Acetone n-hexane (1+8) 3.6 Organic chlorine pesticide standard; Purity ≥ 98%, see Appendix A 3.7 Standard stock solution; Accurately weigh an appropriate amount of each organic pesticide standard and prepare a standard stock solution with a mass concentration of 100 pug/mL using benzene 3.8 Mixed standard working solution; Dilute gradually with benzene as needed to form a series of mixed standard working solutions with suitable concentrations Note: The standard stock solution is stored in the О The shelf life is 12 months when stored in a refrigerator at temperatures ranging from ℃ to 4 ℃, and the mixed standard working solution is stored in a О The shelf life for storage in a refrigerator at temperatures ranging from ℃ to 4 ℃ is 6 months

Instruments and equipment

4.1 Gas chromatograph; Equipped with electron capture detector (ECD) 4.2 Gas chromatography-mass spectrometer: equipped with a mass selective detector (MSD). 4.3 Ultrasonic generator: operating frequency 40 kHz.

4.4 Rotating evaporator.

4.5 Anhydrous sodium sulfate column: 7.5 cm × 1.5 cm (inner diameter), filled with 4 cm high anhydrous sodium sulfate. 4.6 Conical flask: with ground stopper, 100 mL

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