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GB/T 37588-2019 English PDF (GBT37588-2019)

GB/T 37588-2019 English PDF (GBT37588-2019)

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GB/T 37588-2019: Carbon materials -- Determination of nitrogen content -- Dumas combustion method

This Standard specified the principle, reagents, apparatus, specimen preparation, test procedures, calculation results, precision and test report for determining the nitrogen content in carbon materials by Dumas combustion method. This Standard is applicable to the determination of nitrogen content in the carbon materials, such as calcined coke, calcined anthracite, graphite materials, etc.
GB/T 37588-2019
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 29.050
Q 50
Carbon Materials ?€? Determination of
Nitrogen Content ?€? Dumas Combustion Method
ISSUED ON: JUNE 04, 2019
IMPLEMENTED ON: JANUARY 01, 2020
Issued by: State Administration for Market Regulation;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative References ... 4
3 Principle ... 4
4 Reagents ... 5
5 Apparatus ... 5
6 Specimen Preparation ... 5
7 Test Procedures ... 6
8 Calculation of Results ... 6
9 Precision ... 6
10 Test Report ... 7
Carbon Materials ?€? Determination of
Nitrogen Content ?€? Dumas Combustion Method
1 Scope
This Standard specified the principle, reagents, apparatus, specimen preparation, test procedures, calculation results, precision and test report for determining the nitrogen content in carbon materials by Dumas combustion method.
This Standard is applicable to the determination of nitrogen content in the carbon materials, such as calcined coke, calcined anthracite, graphite materials, etc. 2 Normative References
The following documents are essential to the application of this document. For the dated documents, only the versions with the dates indicated are applicable to this document; for the undated documents, only the latest version (including all the amendments) are applicable to this document.
GB/T 1997 Coke -Sampling and Preparation of Samples
GB/T 8170 Rules of Rounding off for Numerical Values and Expression and
Judgement of Limiting Values
3 Principle
The sample, under the existence of high-purity oxide, through 900??C~1050??C high- temperature combustion, makes the nitrogen to release from the sample in the forms of free nitrogen and nitrogen oxides. The carbon dioxide, water vapor and other interference components in the mixed gas produced during the combustion process are absorbed by the absorbent. The nitrogen and nitrogen oxides in the mixed gas are all reduced to the nitrogen by catalytic furnace; after that the nitrogen content is measured by thermal conductivity detector; the instrument microprocessor shall convert the respond signal into the mass fraction of nitrogen and output it. 7 Test Procedures
7.1 Instrument preparation
Start the instrument to check the test system for air tightness. Set the test parameters according to the requirements of the instrument manual; ensure the sample can be fully burned through adjusting the parameters such as temperature, oxygen flow rate, combustion time, etc.
7.2 Calibration curve
Take the measured value of the blank sample as the zero point; successively take 0.02g, 0.04g, 0.06g, 0.08g, 0.10g (accurate to 0.0001g) of EDTA calibration substance (see 4.3); place into the instrument; measure according to the pre-setting procedure of the instrument. Each calibration point shall be measured for 5 times repeatedly. If the range of the 5-time measurement results does not exceed the repeatability limit (r) of this Standard, then the mean value of the 5-measure results shall be taken as the measured value of the calibration point; draw the standard curve by a linear fit method. 7.3 Calibration effectiveness verification
Select 1~2 standard samples (see 4.4) or other control samples; measure the nitrogen in the samples by the instrument that has been calibrated. If the measured value is within the uncertainty range of the standard value (or control value), it indicates that the calibration is effective; otherwise, check out the reasons, and re-calibrate. 7.4 Sample determination
Take approximately 0.05g (accurate to 0.0001g) of specimen; and place into the instrument; measure according to the pre-setting procedure of the instrument; conduct 2~3 parallel tests.
8 Calculation of Results
Read the test data automatically displayed by the instrument. The test result shall take the average value of several parallel tests; retain to two significant digits after the decimal points; the numerical rounding-off shall be carried out as per the provisions of GB/T 8170.
9 Precision
The precision for determination of nitrogen content can refer to Table 1.

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