GB/T 38397-2019Coal tar - Determination of component content - Gas chromatography-mass spectrometry and thermogravimetry (English PDF)

1 Scope

This standard specifies the principles, reagents and materials, instruments and equipment, sample preparation, test procedures, and results for determining the content of compounds in coal tar.

Calculations, method precision and test reports.

This standard is applicable to common compounds (such as 1,2-dimethylbenzene, phenanthrene,

Determination of C22 alkanes, 1,2,3-trimethylnaphthalene, 2,4-dimethylphenol, 1-methylnaphthol, 1,3-dimethylnaphthol, etc.). Coal extract, raw

Oil, biomass pyrolysis oil, etc. can be used by reference.

2 Normative references

The following documents are essential for the application of this document. For dated references, only the dated version applies to this article

Pieces. For undated references, the latest version (including all amendments) applies to this document.

GB/T 260-2016 Petroleum products-Determination of water content-Distillation method

GB/T 1999 Coking oil products sampling method

GB/T 8170 Numerical rounding rules and expression and judgment of limit values

3 Principle

The gas chromatography-mass spectrometer uses a turbo molecular pump and a fore vacuum pump to form a two-stage vacuum unit.The samples to be analyzed are passed through

The sample is injected into the gas chromatograph by the sampler, separated by a capillary column, and ionized into the ion source of the mass spectrometer to generate positive ions.

The positive and negative electrodes send positive ions into the quadrupole system.The quadrupole forms high-frequency electricity under the combination of high-frequency voltage and positive and negative voltage.

Field, under the action of the scanning voltage, the ions reach the ion detector through the center of symmetry of the quadrupole, and then amplified by the ion current amplifier to generate a mass spectrum signal

No., and then get the mass spectrum. By searching with the compound standard library, the constituents and relative contents of unknown samples were identified.

The thermogravimetric analyzer uses a program temperature controller to make the heating electric furnace heat up at a certain heating rate.When the mass of the measured sample changes, the light

The electric sensor can convert the mass change into a direct current signal.The signal is amplified by the weighing amplifier and then fed back to the balance moving coil to generate a reaction.

The electromagnetic moment is driven to reset the balance beam, and the potential difference formed by the feedback is proportional to the mass change.

Weight loss curve, and then get the mass loss of the measured sample and the final weight loss rate at the specified temperature.

The gas chromatograph-mass spectrometer and thermogravimetric analyzer use the same temperature rising procedure.According to the thermal weight loss data of the coal tar sample tested,

The mass of the vaporized part and the final thermal weight loss rate are obtained, and the real sample that enters the gas chromatography-mass spectrometer for detection is obtained indirectly.

Amount (vaporized part), and the mass of the sample remaining in the glass liner (non-vaporized part), so as to obtain the components of the coal tar (vaporization temperature

<=300 °C).

4 Reagents and materials