This standard is applicable to the determination of the average relative molecular weight of industrial linear alkylbenzenes, but not to branched alkylbenzenes. GB/T 5177.3-1985 Determination of the average relative molecular weight of industrial alkylbenzenes - Gas-liquid chromatography method GB/T5177.3-1985 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Determitation of mean relative molecular mass forindustrial alkylbenzene-Gas-liquld chromatographic methodUDC 547.52: 541
GB 5177.3—85
This standard is applicable to the determination of mean relative molecular mass for industrial straight-chain alkylbenzenes, but not for branched-chain alkylbenzenes. 1 Principle
Gas-liquid chromatography is used to determine the carbon number distribution of industrial straight-chain alkylbenzenes and calculate the average relative molecular mass. 2 Instruments
2.1 Chromatograph
2.1.1 Filling column: stainless steel column, 1-6 m long, 2-4 mm inner diameter, filled with high temperature non-polar stationary phase (such as SE300V!01), pre-aged before the test, or glass capillary tube, 20-50 m long. The chromatographic peaks of alkyl fluorine with different carbon atoms should be well separated.
2.1.2 Flame ionization detector.
2.1.3 Electronic integrator or integrator. If these two instruments are not available, the paper cutting weighing method can be used. 2, 1.4 Recorder.
2.1.5 Carrier gas: nitrogen.
2.2 Micro syringe: 1 or 10 μl.
3 Reagents and reference samples
3.1 Reference alkylbenzene: a mixture of alkylbenzenes with known chain lengths, for example, C15 to C15 alkylbenzenes. A product with known composition can be used as a reference sample. This reference sample can be used to verify whether the performance of the chromatograph is normal. 3.2 Acetone: analytical grade.
4 Chromatographic analysis conditions
4.1 Column temperature
4.1.1 Column temperature: based on the properties of the sample, the temperature is between 150 and 180°C. 4.1.2 Program heating: the initial temperature is 140 to 170°C, the heating rate is 2 to 2 minutes, and the final temperature is 180 to 250°C. 4.2 Injection port temperature, 250 to 300°C. 4.3 Carrier gas: depending on the rod type and diameter, the flow rate can be between 0.3 and 40 m/min. 5 Chromatographic analysis
5.1 Preparation of sample
If a capillary column (2.1.1) is used, a mixture of 1 volume of alkyl amine and 1 volume of internal amine (3.2) can be prepared if necessary. Alkyl amine can be used directly when using a packed column (2.1.1). National Bureau of Standards Issued on May 10, 1985
Implemented on January 1, 1986
5. 2 Introduction of sample
GB PTA-BS
Use a syringe (2.2) to inject a sufficient amount of sample (5.1) into the chromatograph so that the obtained chromatogram has an appropriate height. Typical chromatograms are shown in Figures 1 and 2.
市-Cm
.Fig.1 Column chromatogram of alkylbenzene (the peak top number is the substitution position of benzene on the alkyl chain, representing phenyl)6,5
Fig.2 Capillary column chromatogram of alkyl (the middle represents the alkyl)6 Qualitative and quantitative methodsbzxZ.net
6.1 Qualitative
GB 5177.3-85
The components of the sample are determined by comparing the sample chromatogram with the chromatogram of alkylbenzene (3.1). 6.2 Quantitative
Use an electronic integrator or a quadrature meter (2.1.3) or a paper-cut weighing method to determine the peak area of ​​alkylbenzenes with different carbon atoms, and calculate the total peak area. Expression of results
7.1 Calculation method
The percentage of the peak area of ​​alkylbenzene with i carbon atoms to the total area is calculated by formula (【): B,=gix100
The average relative molecular weight of alkylbenzene is calculated by formula (2): M=_100
Wherein: B. The percentage of the peak area of ​​alkylbenzene with i carbon atoms to the total peak area; The average relative molecular weight of alkylbenzene is:
peak area of ​​alkylbenzene with i carbon atoms,
total peak area,
molecular weight of alkylbenzene with i carbon atoms, see the table below.
7.2 Precision
The same alkylbenzene sample was compared and analyzed in 10 laboratories, and the following statistical results were obtained: Average value (average relative molecular weight) 242.6 Repeatability standard deviation
Reproducibility standard deviation
Additional instructions:
This standard was proposed by the Ministry of Light Industry of the People's Republic of China and is technically managed by the Daily Chemical Industry Science Research Institute of the Ministry of Light Industry. This standard was drafted by the Daily Chemical Industry Science Research Institute of the Ministry of Light Industry. The main drafter of this standard is Peng Xianqun.
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