1. Introduction The gas chromatographic determination method of coal tar naphthalene content conforms to GB3704-83. The principle is: according to the alkane, the asphaltene in the coal tar is not dissolved, but the naphthalene has a large solubility, and the alkane is used as the extractant to get out of asphaltene and other. The magazine then analyzes the extract and quantifies it by external standard method.
2. Experimental part 2.1 Instruments and reagents:
Instrument: Zhongke spectrum GC2010 gas chromatograph (with hydrogen flame ionization detector, packed column or capillary column injection system), N2000 chromatography workstation.
Reagents: naphthalene (analytical grade), n-dodecane (analytical grade)
2.2 Chromatographic conditions Capillary: Carrier gas pressure: 0.06Mpa Supplementary gas (high purity nitrogen) Flow rate: 30ml/min Air flow rate: 300ml/min Hydrogen flow rate: 30ml/min Split flow: 30ml/min
Filling: carrier gas (high purity nitrogen) flow: 30ml / min air flow: 300ml / min hydrogen flow: 30ml / min
Oven temperature: 180 Injector: 200 ° C Detector: 200 ° C (filling and capillary are the same)
2.3 Preparation of external standards and samples 2.3.1 Preparation of external standards:
Weigh a certain amount of naphthalene, weigh a certain amount of n-dodecane, dissolve in a volumetric flask, then shake and store. The naphthalene content of the external standard required to be formulated is substantially similar to the naphthalene content of the sample preparation described below.
2.3.2 Preparation of samples:
First extraction: Weigh about 1.5g of mixed coal tar sample, accurate to 0.0002g, placed in a volumetric flask, then add 3~4g n-dodecane, and heat it slightly on electric heater or other heating device The temperature is controlled at about 80 degrees, stirred for 2 to 3 minutes while heating, and then left to stand. After cooling to room temperature, the extract is poured into another volumetric flask of known weight and sealed.
Second extraction: take 3~4g n-dodecane into the volumetric flask containing the residue, perform the second extraction according to the first extraction method, and incorporate the second extraction solution into the first extraction solution. Covered.
The third extraction: the third extraction is carried out in the same manner as above, and the third extraction liquid is incorporated into the above two extraction liquids, and the weight of the extraction liquid is weighed to the nearest 0.001 g, and the mixture is shaken and shaken for use.
2.4: Experiment:
Adjust the chromatograph to a steady state, enter 0.2 ul of external standard, and calculate the correction factor. Under the same conditions, 0.2 ul sample was taken, and the concentration of the sample was calculated by an external standard method;
3. Experimental results and calculations:
After calculating the sample concentration by the external standard method, calculate the naphthalene content in the coal tar by the following formula:
C-like *G test 100
Naphthalene%=-------------- X ---------
G 100-Wf
Where: C-like----the concentration of the sample calculated by the external standard method, %;
G test----the weight of the obtained extract after extraction, g;
G ---- the weight of the coal tar sample, g;
Wf coal tar analysis sample moisture content,%----
Gas Chromatographic Analysis of Naphthalene Content in Coal Tar
2. Experimental part 2.1 Instruments and reagents:
Instrument: Zhongke spectrum GC2010 gas chromatograph (with hydrogen flame ionization detector, packed column or capillary column injection system), N2000 chromatography workstation.
Reagents: naphthalene (analytical grade), n-dodecane (analytical grade)
2.2 Chromatographic conditions Capillary: Carrier gas pressure: 0.06Mpa Supplementary gas (high purity nitrogen) Flow rate: 30ml/min Air flow rate: 300ml/min Hydrogen flow rate: 30ml/min Split flow: 30ml/min
Filling: carrier gas (high purity nitrogen) flow: 30ml / min air flow: 300ml / min hydrogen flow: 30ml / min
Oven temperature: 180 Injector: 200 ° C Detector: 200 ° C (filling and capillary are the same)
2.3 Preparation of external standards and samples 2.3.1 Preparation of external standards:
Weigh a certain amount of naphthalene, weigh a certain amount of n-dodecane, dissolve in a volumetric flask, then shake and store. The naphthalene content of the external standard required to be formulated is substantially similar to the naphthalene content of the sample preparation described below.
2.3.2 Preparation of samples:
First extraction: Weigh about 1.5g of mixed coal tar sample, accurate to 0.0002g, placed in a volumetric flask, then add 3~4g n-dodecane, and heat it slightly on electric heater or other heating device The temperature is controlled at about 80 degrees, stirred for 2 to 3 minutes while heating, and then left to stand. After cooling to room temperature, the extract is poured into another volumetric flask of known weight and sealed.
Second extraction: take 3~4g n-dodecane into the volumetric flask containing the residue, perform the second extraction according to the first extraction method, and incorporate the second extraction solution into the first extraction solution. Covered.
The third extraction: the third extraction is carried out in the same manner as above, and the third extraction liquid is incorporated into the above two extraction liquids, and the weight of the extraction liquid is weighed to the nearest 0.001 g, and the mixture is shaken and shaken for use.
2.4: Experiment:
Adjust the chromatograph to a steady state, enter 0.2 ul of external standard, and calculate the correction factor. Under the same conditions, 0.2 ul sample was taken, and the concentration of the sample was calculated by an external standard method;
3. Experimental results and calculations:
After calculating the sample concentration by the external standard method, calculate the naphthalene content in the coal tar by the following formula:
C-like *G test 100
Naphthalene%=-------------- X ---------
G 100-Wf
Where: C-like----the concentration of the sample calculated by the external standard method, %;
G test----the weight of the obtained extract after extraction, g;
G ---- the weight of the coal tar sample, g;
Wf coal tar analysis sample moisture content,%----
Gas Chromatographic Analysis of Naphthalene Content in Coal Tar
Laser Tracker,Laser Tracking System,Tracker Laser,Laser Tracking Equipment
Automated Precision Inc. , https://www.apiasean.com