GB/T 8984.2-1997 Determination of Total Content of Carbon Monoxide, Carbon Dioxide and Hydrocarbons by Gas Chromatography
This standard specifies the determination of total content of carbon monoxide, carbon dioxide, and hydrocarbons in gases by gas chromatography, and provides guidance for principles, reagents and materials, instruments and equipments, sampling, sampling instruments and sampling method, test procedures, calculation and expression of results, precision and quality assurance, and safety.
1. Scope
This standard specifies the determination of total content of carbon monoxide, carbon dioxide and hydrocarbons in gases by gas chromatography.
This standard is applicable to the determination of total content of carbon monoxide, carbon dioxide and hydrocarbons in gases. It can also be used for the analysis of the content of each component of carbon monoxide, carbon dioxide and hydrocarbons, if the appropriate standard chromatographic conditions and detector (see Note 1) can be achieved.
Note 1 : Detectors suitable for the determination of carbon monoxide, carbon dioxide and hydrocarbons are described in GB/T 8981.
2. Reagents and Materials
Unless otherwise noted, the reagents and materials used in the test shall conform to GB/T 6678 or the specific requirements of this standard.
3. Instruments and Equipments
3.1 Chromatographic device
Capillary gas chromatograph, see GB/T 8981.
3.2 Detector
Qualified flame ionization detector (FID) or thermal conductivity detector (TCD), see GB/T 8981.
3.3 Reference standard
a) The certified reference material shall have a certified range (with an absolute deviation of no more than 10%), and the upper and lower limits (or certified values and expanded uncertainty) of the certified range shall cover the range of measurement results of the tested object:
b) Certified reference material suitable for determination of CO, CO2 and hydrocarbons, see Tables 1 and 2 for applicable suitable guidelines.
4. Sampling
4.1 The sampling device and the sampling method of gas shall comply with GB/T 8984.1 and part of them shall comply with GB/T 8984.3.
4.2 In order to reduce the impact of sampling, sampling from multiple sampling points is recommended.
5. Test Procedures
5.1 Sample pre-treatment
5.1.1 From the sampling line, connect the sample to the inlet of the gas chromatograph, flush the line with nitrogen to expel all air, and connect the injection port with a valve, if necessary.
5.1.2 Inject the sample into a sample preparation device (container, heated vessel, separatory funnel, etc.), and add a proper amount of buffer solution, sample pre-treatment reagent, etc., so that the sample is analyzed in a suitable state.
5.1.3 Prepare the sample according to the specific requirements of the sample preparation device and the gas chromatograph.
5.2 Chromatographic separation
5.2.1 According to the determination requirements, install the column recommended in Table 1 and the column suitable for the tested object in the chromatograph, and make a chromatographic start.
5.2.2 Optimize the chromatographic parameters, such as the temperature of the injector, the temperature of the oven, the flow rate of the mobile phase, the pressure of the column head, the type of detector and its parameters, etc., according to Table 2 and the specific substances to be measured.
5.2.3 When the peak shape and height are stable, the chromatograph is ready for the test.
5.3 Chromatographic analysis
5.3.1 Take the chromatograph as a baseline before carrying out chromatographic analysis.
5.3.2 Divide the volume of the injection sample into several small portions and inject them successively into the chromatograph. Weigh each portion of the sample if necessary.
5.3.3 Collect the chromatograph signals of the components of CO, CO2, and hydrocarbons into signals, and record the chromatograph peak areas.
6. Calculation and Expression of Results
6.1 Calculate the total content of CO, CO2, and hydrocarbons in the tested object according to the following formula:
Expression of results:
CO - mass fraction,% (m/m);
CO2 - mass fraction,% (m/m);
Total content of hydrocarbons - mass fraction,% (m/m).
7. Precision
7.1 Reproducibility
7.1.1 The relative standard deviation of the absolute value of the mixture of the content of the three components of CO, CO2, and hydrocarbons (mass fraction) obtained by repeated determinations performed by the same analyst with the same apparatus under the same operating conditions is not more than 5.0%.
7.1.2 The relative standard deviation of the absolute value of each component of the tested gas sample obtained by repeated determinations performed by the same analyst with the same apparatus under the same operating conditions is not more than 10.0%.
7.2 Repeatability
7.2.1 The relative standard deviation of the absolute value of the mixture of the content of the three components of CO, CO2, and hydrocarbons (mass fraction) obtained by repeated determinations performed by the same analyst with the same apparatus under the same operating conditions is not more than 2.0%.
7.2.2 The relative standard deviation of the absolute value of each component of the tested gas sample obtained by repeated determinations performed by different analysts with the same apparatus under the same operating conditions is not more than 6.0%.
8. Quality Assurance
8.1 If a quality system has been established in the laboratory, it shall meet the requirements of GB/T, etc.
8.2 The test results shall be made into a record form, which must be preserved.
8.3 The laboratory shall establish basic documents and calibration files, and records and reports related to the evaluation of the test results in accordance with the requirements of ISO/IEC 17025, GB/T and other relevant standards.
9. Safety
9.1 Those who operate the gas chromatograph should have been trained, and should understand and be familiar with the operation and maintenance of the instrument, and take responsibility for the operation.
9.2 When the laboratory carries out the test according to this standard, it shall comply with the relevant safety regulations.
9.3 Gas chromatograph operators and relevant personnel must wear labor protective equipment such as masks, protective clothing and safety glasses.
