1 Scope of application 1.1 This standard is applicable to the analysis of six hundred sixty-six and DDT in soil.
1.2 This method uses acetone-petroleum ether extraction, purification with concentrated sulfuric acid, and determination with a gas chromatograph with an electron capture detector.
1.3 The minimum detection concentration of this method is 0.00005 ～ 0.00487mg / kg.
2 Reagents and materials
2.1 Carrier gas
Nitrogen, with a purity of 99.99%, is filtered through a deaerator, the oxygen content is less than 5ppm, and the hydrogen content is less than 1.0ppm.
2.2 Reagents and materials used in the preparation of standard samples and samples
The reagent system used is analytically pure, the organic solvent is re-evaporated, concentrated 20 times, and the spectrum is used to determine no interference peak.
2.2.1 Chromatographic standard samples: α-66, β-66, γ-66, δ-66, p, p / -DDE, o, p / -DDT, p, p /- DDD, P, P / -DDT, content 98% ～ 99%, chromatographically pure.
2.2.2 Petroleum ether, boiling range 60 ～ 90 ℃.
2.2.3 Acetone (CH3COCH3).
2.2.4 Isooctane (C8H18).
2.2.5 Benzene (C6H6): superior grade pure.
2.2.6 Concentrated sulfuric acid (H2SO4): density is 1.84g / mL.
2.2.7 Anhydrous sodium sulfate (Na2SOt): Bake in a 300 ° C oven for 4h and set aside.
2.2.8 Sodium sulfate solution: 20g / L.
2.2.9 Diatomite: reagent grade.
2.2.10 Chloroform (CHCl3).
2.2.11 Absorbent cotton (or glass wool); reflux with acetone for 16h, take out and dry it for use
2.3 Reagents and materials used in the preparation of chromatographic columns
2.3.1 Column and packing (3.6.5).
2.3.2 Solvent chloroform (2.2.10) used for coating fixing solution.
3 Instruments
3.1 Main instrument: gas chromatograph with electron capture detector.
3.2 Pressure gauge and flow meter to control carrier gas.
3.3 Sampler: All-glass system sampler.
3.4 Recorder: A recorder that matches the instrument.
3.5 Gas chromatography detector:
3.5.1 Type; electronic capture detector.
3.5.2 Characteristics of the device: 63Ni radioactive source or high temperature 3H radioactive source can be used.
3.5.3 Detector polarization voltage: DC power supply or pulse power supply can be used.
3.6 Column:
3.6.1 Number of chromatographic columns: 2 to 3.
3.6.2 Column characteristics:
3.6.2.1 Material: hard glass.
3.6.2.2 Dimensions: length 1.8 ～ 2.0m, inner diameter 2 ～ 3mm.
3.6.3 Chromatography type: spiral packed column.
3.6.4 Chromatographic column pretreatment: After washing with water, fill the glass column tube with hot washing liquid (60 ～ 70 ℃). Soak for 4h, then rinse to neutrality with water, then rinse with distilled water, dry and then silanized, fill 6% -10% dichlorodimethylsilane methanol solution into the glass column tube, soak for 2h, then use methanol Clean to neutral and dry for use.
3.6.5 Filling:
3.6.5.1 Carrier: chromosorb W AW-DMCS or chromosorb W AW-DMCS-HP, 80-100 mesh.
3.6, 5.2 Fixative: OV-17 (methyl silicone), the maximum operating temperature is 350 ℃; QF-1 or OV-210 (trichloropropylmethyl silicone), the maximum operating temperature is 250 ℃ or 275 ℃
3.6.5.2.1 Liquid phase loading: OV-17 is 1.5%; OV-210 or QF-1 is 1.95%.
3.6.5.2.2 Method of applying fixative solution: Weigh according to the weight of the support-a fixed amount of fixative solution, dissolve in chloroform, after completely dissolved, pour into the beaker containing the support. Then add chloroform (2.2.10) to the liquid level 1 ~ 2cm higher, shake and soak for 2h. Then evaporate the solvent to dryness under an infrared lamp or slowly evaporate to dryness on a rotary evaporator, and then place it in an oven at 120 ° C, and place it for 4 hours before use.
3.6.5.3 Packing method of the chromatographic column: plug one end of the chromatographic column (connected to the detector) with silanized glass wool, connect it to the vacuum pump, and connect a funnel to the other end. After starting the vacuum pump, slowly pour the stationary phase into the column Gently tap the chromatographic column to make the stationary phase packed tightly in the chromatographic housing until the stationary phase is no longer pumped into the column.
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