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Carbon materials - Determination of nitrogen content - Dumas combustion method
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GB/T 37588-2019: PDF in English (GBT 37588-2019) GB/T 37588-2019
NATIONAL STANDARD OF THE
PEOPLE’S 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 & 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.
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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