GB/T 30733-2014Determination of total carbon, hydrogen and nitrogen content in coal -- Instrumental method (English PDF)

4.1 Carrier gas. Choose the helium specified by the instrument's instructions or other suitable

gas.

problems. Calibrate the instrument according to 7.2 when necessary. Determine the tested

values which have already be done before the check. The calibration check is recommended

at the beginning and at the end of each lot of samples. The calibration check shall be

conducted after every 10 times of sample determinations during the determination.

8.1 Calculation of the hydrogen content in the coal

Calculation of the hydrogen content in the coal is calculated in accordance with the Formula (1).

Where.

Had-- The hydrogen content in the coal is valued by mass fraction (%);

Ht,ad-- The total hydrogen content measured by instrument is valued by mass fraction (%);

Mad-- The air-dried moisture content in the coal sample (determined by GB/T 212) is valued

by mass fraction (%).

8.2 Calculation of the organic carbon content in the coal

When determination of the organic carbon (Co,ad) is necessary, calculate it in accordance with

the Formula (2).

Where.

Co,ad-- The organic carbon content in the coal is valued by mass fraction (%);

Cad-- The total organic carbon content measured by instrument is valued by mass fraction (%);

(CO2)ad-- The content of carbon dioxide in carbonate (determined by GB/T 218) is valued

by mass fraction (%).

8.3 Results expression

The carbon, hydrogen and nitrogen content (valued by mass fraction, %) of the sample is

reported according to the average value after determined twice, accurate to 0.01% according

to GB/T 483.

Annex C

(Informative)

Examples of instrument calibration method

C.1 Determine the content range of carbon, hydrogen and nitrogen in the daily determined

coal. Determine the quantity of coal sample according to the instrument specification.

Calculate the content range of the calibration material according to Formula (C.1). If choosing

pure substance as the calibration substance, then take its metering data as the standard

values; if choosing certified coal standard substance as the calibration substance, then convert

the standard values to the air-dry basis value.

mstandard = m·x...(C.1) X standard

Where.

mstandard -- The unit of the sample weight of the calibration material, g;

m -- The unit of the sample weight specified in the instrument specification, g;

X-- Measurement range (%) of each element content;

Xstandard -- Standard value (%) of standard substance.

If choosing single-point calibration, then.

mstandard = m...(C.2)

C.2 Examples.

the carbon content range of the daily determined coal sample is 40.00%~70.00%; the

hydrogen content range is 3.00%~4.00%; the nitrogen content range is 0.60%~1.00%. The

specified sample weight in the instrument specification is 80mg. Choose EDTA as the

calibration material to fit the calibration curve of carbon and hydrogen. And choose the certified

coal standard substance as the calibration material to fit the calibration curve of the nitrogen.

EDTA's measuring value is carbon. 41.098%; Hydrogen. 5.518%. The standard values of the

certified coal standard substance is nitrogen. 0.82%.

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