The halogenated hydrocarbons in the collected surface water samples were adsorbed by solid-phase microextraction fibers, enriched in the headspace, and detected by gas chromatography and electron capture detector (ECD). Qualitative by chromatographic retention time and quantitative by external standard method.
1. Experimental water: double distilled water or laboratory first-grade pure water. Before use, perform a blank check to confirm that there is no interference of the target compound or the concentration of the target compound is below the detection limit of the method.
2. Methanol: chromatographically pure. Before use, perform a blank check to confirm that there is no interference of the target compound or the concentration of the target compound is below the detection limit of the method.
3. Sodium chloride: before use, burn in a muffle furnace at 400°C for 4 hours, cool to room temperature in a desiccator, and transfer to a ground glass bottle for storage.
4. Ascorbic acid.
5. Sodium thiosulfate.
6. Standard solution: 100mg/L-2000mg/L, commercially available certified standard solution with methanol as solvent.
7. Carrier gas: high-purity nitrogen, with a purity greater than 99.999%, deoxidized by deoxidizer and dehydrated by molecular sieve.
1. Gas chromatograph: with split/splitless inlet, electron capture detector (ECD), temperature programmable.
2. Chromatographic column: Quartz capillary column, 60m (length) × 0.25mm (inner diameter) × 1.4 μm (film thickness), the stationary phase is 6% cyanopropylbenzene-94% dimethylsiloxane, or others Efficient capillary column.
3. Solid phase microextraction device:
SPE bench; SPE handle; SPE fiber (SPME): Divinylbenzene/Carboxen/Dimethicone), or other equivalent extraction fibers. Before the first use, the extracted fibers should be placed in the injection port for aging.
4. Gas chromatograph liner: no glass wool liner.
5. Glass microsyringe: 10uL-250uL.
6. Headspace vial: 15mL or 20mL headspace vial, with sealing gasket (polytetrafluoroethylene/silicon rubber material), sealing cap (screw cap or single-use gland), can also be used with headspace sampler Matching glass headspace vials.
7. Sampling bottle: 40mL brown screw-top glass bottle with a silicone rubber-PTFE liner screw cap.
8. Other commonly used laboratory equipment.
The collection of surface water samples and groundwater samples shall be carried out in accordance with relevant regulations. When collecting water samples, do not wash with water samples, and the water samples should overflow in the water sample bottle without leaving space. When sampling, try to avoid or reduce the exposure of water samples to the air. All water samples were collected in parallel, sealed and labelled immediately after sampling.
water sample preservation
After the water samples were collected, without adding any preservatives, they were immediately placed in a refrigerator for transportation at a temperature below 4°C, and the water sample analysis was completed within 24 hours. If the water sample contains residual chlorine, add 0.3g-0.5g ascorbic acid or sodium thiosulfate to the sampling bottle.
Weigh 2.5g of NaCl into the headspace bottle, slowly add 10.0mL of experimental water, and then add a certain volume of standard solution to prepare a calibration curve series, and inject samples according to the reference conditions of the instrument for analysis.
Draw the calibration curve with the peak height or peak area as the ordinate and the concentration of the target compound as the abscissa.
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