毛細管柱測氣態(tài)制冷劑 10 種鹵代烴  測試譜圖：




Capillary column measurement of gaseous refrigerants 10 kinds of halogenated hydrocarbons
Capillary column measurement of gaseous refrigerants 10 kinds of halogenated hydrocarbons Details:

Name: Capillary Column
Specification: 60m*0.32mm
Model: Porous layer open tube capillary column PLOT silica gel
Application: gaseous refrigerant determination of 10 halogenated hydrocarbons gas chromatography-mass spectrometry

1 Scope of application


      This standard specifies the determination of trifluoromethane (HFC-23), difluoromethane (HFC-32), pentafluoroethane (HFC-125), 1,1,1-trifluoroethane (HFC- 143a), dichlorodifluoromethane (CFC-12), monochlorodifluoromethane (HCFC-22), 1,1,1,2-tetrafluoroethane (HFC-134a), 1,1-difluoroethane 10 kinds of halogens including HFC-152a, 1-chloro-1,2,2,2-tetrafluoroethane (HCFC-124) and 1-chloro-1,1-difluoroethane (HCFC-142b) Gas Chromatography-Mass Spectrometry of Substituted Hydrocarbons.

      This standard applies to the volume fraction of HFC-23, HFC-32, HFC-125, HFC-143a, CFC-12, HCFC-22, HFC-134a, HFC-152a, HCFC-124 and HCFC-142b in gaseous refrigerants. The determination is not suitable for the determination of the purity of the above-mentioned compounds.

      When the sampling volume is 20.0 μl, the detection limit of the method for 10 halogenated hydrocarbons is 0.08%～0.09%; the lower limit of determination is 0.32%～0.36%. See Appendix A for details.

2 Normative references


      This standard refers to the following documents or their clauses. For dated reference documents, only the dated version is applicable to this standard. For undated reference documents, the latest version (including all amendments) is applicable to this standard.

      GB/T 3723 General rules for the sampling safety of industrial chemical products

      GB/T 6678 General Rules for Sampling of Chemical Products

      GB/T 6681 General Rules for Sampling of Gas Chemical Products

      GB/T 26571 Special Gas Storage Period Specification

      GB/T 37994 General Rules for Sampling of Mixed Refrigerants

      SN/T 2537 Sampling method for import and export refrigerant inspection

3 Terms and definitions


      The following terms and definitions apply to this standard.

3.1

      Refrigerant

      The fluid used to transfer heat in the refrigeration system absorbs heat in a low-temperature and low-pressure environment, and releases heat in a high-temperature and high-pressure environment, usually accompanied by a phase change process.

3.2

      Gaseous refrigerant

      It is a gaseous refrigerant at a temperature of 20 ℃ and a pressure of 101.3 kPa.

4 Principles of the method


      Under certain temperature conditions, the target compounds in the sample are mixed in the headspace sample bottle and reach equilibrium, then separated by gas chromatography and detected by a mass detector. It is qualitatively compared with the retention time of the standard substance and the mass spectrum, and quantified by the internal standard method.

5 Reagents and materials


      Unless otherwise specified, analytical reagents conforming to national standards are used for analysis. The experiment water is double distilled water without target compound or water prepared by pure water equipment.

5.1 Trifluoromethane (HFC-23), purity ≥99.5%, stored in a steel cylinder, refer to the relevant instructions of the certificate for storage.

5.2 Difluoromethane (HFC-32), purity ≥99.5%, stored in a steel cylinder, refer to the relevant instructions of the certificate for storage.

5.3 Pentafluoroethane (HFC-125), purity ≥99.5%, stored in a steel cylinder, refer to the relevant instructions of the certificate for storage.

5.4 1,1,1-Trifluoroethane (HFC-143a), purity ≥99.5%, stored in a steel cylinder, refer to the relevant instructions of the certificate for storage.

5.5 Dichlorodifluoromethane (CFC-12), purity ≥99.0%, stored in a steel cylinder, refer to the relevant instructions of the certificate for storage.

5.6 Monochlorodifluoromethane (HCFC-22), purity ≥99.6%, stored in a steel cylinder, refer to the relevant instructions of the certificate for storage.

5.7 1,1,1,2-Tetrafluoroethane (HFC-134a), purity ≥99.5%, stored in a steel cylinder, refer to the relevant instructions of the certificate for storage.

5.8 1,1-Difluoroethane (HFC-152a), purity ≥99.5%, stored in a steel cylinder, refer to the relevant instructions of the certificate for storage.

5.9 1-Chloro-1,2,2,2-tetrafluoroethane (HCFC-124), purity ≥99.5%, stored in a cylinder, refer to the relevant instructions of the certificate for storage.

5.10 1-Chloro-1,1-difluoroethane (HCFC-142b), purity ≥99.5%, stored in a steel cylinder, refer to the relevant instructions of the certificate for storage.

5.11 Internal standard compound: 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea), purity ≥99.6%, stored in a cylinder, refer to the relevant instructions of the certificate for storage.

5.12 4-Bromofluorobenzene (BFB) solution: ρ(C6H4BrF)=25 mg/L, the solvent is a commercially available certified standard solution of methanol, and it should be stored in accordance with the relevant instructions of the standard solution certificate.

5.13 Nitrogen, purity ≥99.999%.

5.14 Carrier gas: helium, purity ≥99.999%.

6 Apparatus and equipment


6.1 Sampling catheter: made of stainless steel or other corrosion-resistant metal pipes or polytetrafluoroethylene plastic pipes. Before sampling, place the sampling catheter in a 110 ℃ oven for 1 hour. After sampling, the sampling catheter should be removed in time and kept properly. Keep the catheter clean and dry to prevent debris or dirt from entering. For on-site sample collection, it is used to connect large steel cylinders or container pressure storage tanks and air bags (6.2); for laboratory sample preparation, it is used to connect small steel cylinder samples equipped with pressure relief valves (6.3) and air bags (6.2). ).

6.2 Air bag: fluoropolymer film air bag or aluminum-plastic composite film air bag, with a micro-syringe sampling valve, with a sampling tube (6.1) connector, the sampling valve has the function of opening and closing the air bag at the same time.

6.3 Pressure reducing valve: installed at the mouth of the sample small steel bottle, used for gas pressure reduction during laboratory sampling.

6.4 Gas Chromatograph-Mass Spectrometer: The chromatographic part has a split/splitless inlet, and the column oven can be programmed to increase temperature; the mass spectrometer has a 70 eV electron bombardment ion source.

6.5 Headspace autosampler: It has the function of sampling loop or injection needle.

6.6 Headspace sampling bottle: the bottle body is made of glass, the sealing gasket is made of PTFE/silicone rubber, and the sealing cap is screw cap or disposable gland, 20 ml, or with the headspace autosampler (6.5) Matching glass bottle. Tighten (press) the sealing cap before use to ensure the air tightness of the headspace sample bottle.

6.7 Chromatographic column: a porous layer open-tube capillary column, 60 m (column length) × 0.32 mm (inner diameter), the stationary phase is bonded silica gel, or other equivalent capillary columns.

6.8 Syringe: air-tight syringe, glass material, 10.0 μl, 25.0 μl, 250 μl, 500 μl, 100 ml.

6.9 Commonly used instruments and equipment in general laboratories.

7 samples


7.1 Sample collection and storage

      Before sample collection, first understand the actual situation of the collected samples. For sample collection, refer to the relevant regulations of GB/T 6678, GB/T 6681 and GB/T 37994, and for sample storage, refer to the relevant regulations of GB/T 26571 and SN/T 2537.

      When the samples are stored in non-refillable cylinders or refilled cylinders (volume W10 L, hereinafter referred to as "small cylinders"), they shall be taken according to the production batch, and one small cylinder sample shall be taken from the same batch number and transported back to the laboratory; the samples shall be stored in When storing tanks, tank trucks or refilling steel cylinders (volume> 10L), one can (bottle) is sampled from the same batch number. When sampling, connect one end of the sampling pipe (6.1) to the sampling port valve of the sample container, and the other end to Connect the air bag (6.2), open the valve material and slowly introduce the sample into the air bag (6.2). After sampling, tighten the valve of the air bag to collect 2 parallel samples, 1 for analysis, and 1 for storage.

      The collected small steel cylinder samples are transported and stored under sealed conditions at room temperature. During the loading and unloading process, impact, drag, drop and direct exposure are strictly prohibited. They should be stored in a cool and dry place. The room is well ventilated and should not be close to heat sources. Sun and rain; the samples collected in the air bag (6.2) should be transported and stored in the dark at room temperature and stored in a cool and dry place. The test will be completed within 7 days.

      Note: Before using the air bag for sampling, check and ensure that the air bag (6.2) is well sealed; clean with nitrogen (5.13) for 3 times and then reserve; when sampling, first clean the air bag (6.2) with sample gas for 3 times, and then Collect samples.

7.2 Preparation of test samples

      Small cylinder sample: first clean the air bag (6.2) with nitrogen (5.13) 3 times, then replace the air bag (6.2) with the sample 3 times, and then set aside. Connect the pressure reducing valve (6.3) to the small steel cylinder, slowly open the valve of the small steel bottle and the pressure reducing valve (6.3), and release the sample to replace the gas in the pipeline of the pressure reducing valve (6.3). Then immediately connect the pressure reducing valve (6.3) and the cleaned air bag (6.2) with the sampling pipe (6.1), open the pressure reducing valve (6.3),

      Transfer an appropriate amount of gas sample to the gas bag (6.2). See Figure 1 for a schematic diagram of sample sampling from a small steel cylinder. Use an air-tight syringe (6.8) to remove a 20.0 M sample from the above air bag and put it into the headspace sample vial (6.6) through a sealing gasket, and add 1,1,1, to the headspace sample vial (6.6). 2,3,3,3-Heptafluoropropane internal standard (5.11) 10.0μl, to be tested.


Capillary column test gaseous refrigerant 10 kinds of halogenated hydrocarbon test spectrum: