GB/T 5178-1985 Determination of average relative molecular weight of industrial linear alkylbenzene sulfonate by gas-liquid chromatography
Some standard content:
National Standard of the People's Republic of China
Determinition of mean relative molecular mass for technical straight-chain sodium atkylbenzenesulphonates-Gas-liquid chromatographic method
This standard specifies the method for determining the mean relative molecular mass of technical straight-chain sodium atkylbenzenesulphonates. This standard is equivalent to the international standard ISO6841-1983 "Surface active agents-Determination of relative molecular mass-Gas-liquid chromatography".
UDC 547.54-541
GB 5176—85
Industry Sodium linear alkylbenzene sulfonate -
Average phase
An accurate and rapid method for determining the average relative molecular mass of sodium linear alkylbenzene sulfonate is to determine the average relative molecular mass of desulfonated alkylbenzene by gas-liquid chromatography, and then calculate by adding the formula weight of SO,Na group minus the original amount of hydrogen. This method uses nuts and hollow bolts, and seals the cracking tube with silicone rubber and polytetrachloroethylene pads to allow the desulfonation reaction to proceed in it. Compared with the method of 1S06841 using oxygen gas or oxygen-air flame sealed combustion, it is simpler, and the cracking tube can be used repeatedly. Gas-liquid chromatography is only applicable to linear alkylbenzene, because the chromatographic peak of branched alkylbenzene cannot be identified. 1 Principle
The sample is desulfonated in concentrated phosphoric acid medium, and the released alkylbenzene is extracted with petroleum ether benzene. Determine the average relative molecular weight of the extracted alkylbenzene by gas-liquid chromatography.
Calculate the average relative molecular weight of sodium alkylbenzene sulfonate. 2 Reagents and reference samples
Analysis-grade reagents, distilled water or water of equivalent purity should be used in the analysis. 2.1 Phosphoric acid, 85% (m/m) solution.
2.2 Petroleum ether, free of aromatic compounds, distillation range 30-60°C. 2.3 Anhydrous sodium sulfate.
2.4 Sodium hydroxide, 160g/ml solution.
2.5 Reference alkylbenzene: a mixture of alkylbenzenes of known chain length, such as C. to C15 alkyl extracts. Products with known composition can be used as reference samples. This reference sample can be used to check whether the performance of the chromatograph is normal. 2.6 Carrier gas, nitrogen 2.
2.7 Indole (as needed).
Instructions for use,
1) According to Chinese custom, the carbon number of alkanes does not include the carbon number of the benzene ring, while ISO 6841: includes the carbon number of the benzene ring. 2) When my country's gas chromatograph uses a flame ionization detector, most of them use nitrogen as the carrier gas. The hydrogen, hydrogen and effect gas specified in ISO 68414 are not suitable for my country's specific conditions.
National Bureau of Standards 1985-0610 issued
1986-01-01 implementation
GB 5178-85
3 Instruments! )
3.1 Pyrolysis tube, hard glass tube with an outer diameter of 11mm and a length of 60mm (wall thickness of about 1mm), with the tube mouth flanging, see Figure 1a. 8.2 Nuts and hollow bolts, which can be used to seal the pyrolysis tube (3.1) with silicone rubber and polytetrafluoroethylene film, see Figure 16 and Figure 1c. 3. Metal safety tube, which can accommodate the pyrolysis tube (3.1) to prevent the pyrolysis tube from rupturing, with a screw cover on the top, see Figure 2. 3.4 Heating device, a metal block with holes, or other uniform heat source that can control the temperature to about 250°C. When using a metal block with holes, the hole diameter should match the outer diameter of the metal safety tube (3.3) so that the metal safety tube fits in it. The metal block should also have a small hole for inserting a thermometer (Figure 3).
Figure 1 Thermal cracking tube and sealing device
— Thermal cracking tube 11×60; b (1) — hollow bolt, b (2) — screw bolt: — Sealing device: 1 — silicone rubber, 2 — polyvinyl fluoride membrane
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Figure 2 Safety tube with screw cover
Instructions for use:
1) The desulfonation device of this method is composed of thermal cracking camp, screw phase and hollow screw light, which can be heated by gold block, ISU6811 adopts oxygen-gas air flame sealing combustion, and is heated by ten silicon sleeves. 120
GB 5178--85
±25 × 85
Figure 3 Metal block with holes for heating
a- Place the gold rat gauge, b- Take the thermometer hole 3.5 Closed electric furnace, power 1.5~2.0kw, 3.6 Voltage regulating transformer.
3.7 Stoppered test tube, diameter 12mm, length 120mm. 3.8 Pipette.
3.9 Beaker, 5 or 10ml.
3.10 Conical sample tube, 1ml.
3.11 Chromatograph.
Capillary column, 20-50 m long, spiral, inner diameter about 0.25 mm, outer diameter about 1.1 mm, coated with high temperature non-polar factor $.11.1
phase (such as SE30, OV101), pre-aged before the experiment: or use filler, length! ~ 6 m, the chromatographic peaks of thiobenzene with different carbon atoms should be well separated.
3.11.2 Flame ionization detector.
3.11.3 Electron integrator or integrator.
When these two instruments are not available, the paper cutting weighing method can be used. 3.11.4 Recorder.
s.11.5 Syringe, 5 or 10μl.
Test procedure
4.1 Sample
Take about 0.1 g of sample and draw it into the pyrolysis tube (3.1). 4.2 Desulfonation 2)
Add 2 ml of phosphoric acid solution (2.1) to the pyrolysis tube containing the sample, install the nut and hollow breaker (3.2) with silicone rubber and polyvinyl fluoride membrane, and tighten them slightly. Place the sealed pyrolysis sample in a safety tube (3.3) and screw on the screw cap. Place the safety tube in a heating device (3.4) at about 25°C for reaction for about 15 minutes, remove the safety tube, cool it with water, and then remove the sealed pyrolysis tube.
Open the pyrolysis tube and transfer the contents to a stoppered test tube (3.7), rinse the pyrolysis tube with 2 ml of petroleum ether (2.2), and rinse the pyrolysis tube. Note:
1) The method is to determine the carbon number distribution of the dealkylated sample by gas-liquid chromatography. Thus, its average distribution is calculated. When sampling, no accurate weighing is required.
2) This method uses snail milk and hollow warm plugs to heat the double-solution tube to remove the sulfonic acid in the sample: 1S0G41 uses coal (or air-coal combustion front) to make the sample in the area.
GB 51T8:--1E:
Transfer the washing liquid into this test tube.
Screen the test tube stopper and shake it, let it stand and separate, and use a pipette (3.8) to transfer the petroleum ether layer to a second stoppered test tube. Add 2ml petroleum ether to the first test tube, cover the tube stopper, shake it and let it stand and separate. Use a pipette to transfer the petroleum ether layer to the second test tube and combine it with the first extraction liquid. Add an equal volume of water to the combined petroleum ether extract, plug the test tube stopper, shake it and let it stand and separate, use a pipette to suck out the lower layer of water and discard it, and weigh it. Repeat this operation 4-5 times. Add 1 ml of sodium hydroxide solution (2.4) to the washed petroleum ether layer, plug the test tube, shake and let it stand to separate, and use a pipette to suck out the lower water layer and discard it.
Add about 1 g of anhydrous sodium sulfate (2.3) to the petroleum ether extract, plug the test tube, shake, and let it stand for 20 minutes. Transfer the petroleum ether extract to a beaker (3.9), gently heat it on a water bath at 60-70 degrees Celsius to evaporate most of the petroleum ether, and then transfer it to a sample tube (3.10) to continue evaporation. 4.3 Chromatographic analysis
4.3.1 Chromatograph
4.3.1.1 Injection port, temperature above 250°C. 4.8.1.2 Column 2)
: Constant temperature: depending on the nature of the sample, the temperature is between 150 and 180°C. b. Program temperature rise: the starting temperature is 140-170℃, and the temperature is raised to the final temperature of 180-250℃ at a rate of 0.5-2℃/min. 4.8.1.3 Carrier gas: according to the column type and diameter, the flow rate is 0.3-40ml/min. 4.3.1.4 Detector conditions: the temperature is greater than 250℃. 4.3.2 Instrument performance test
Inject a certain amount of reference alkylbenzene (2.5) into the chromatograph so that the spectral peaks of the alkylbenzene with different carbon numbers can be well separated, and record the retention time for comparison with the sample.
4.3. Test
4.3.3.1 Preparation of sample: if a capillary column (3.11:1) is used, a mixture of 1 volume of alkylbenzene extract (4.2) and 1 volume of acetone (2.7) can be prepared if necessary. If a packed column (3.11.1) is used, the alkylbenzene extract can be used directly. 4.3.3.2. Sample introduction: Use a syringe (3, 11.5) to inject a sufficient amount of test solution (4.3.3.1) into the chromatograph so that the peak height of the obtained chromatogram is appropriate.
A typical chromatogram is shown in Figure 4.
Introduction:
1) In this method, the sample is first washed with water to remove the phosphorus in the ether layer so that it is easy to separate when the ether layer is neutralized with sodium hydroxide. Washing and neutralizing the ether layer directly with sodium hydroxide is usually not conducive to separation. 2) According to the laboratory conditions in my country, constant temperature and programmed temperature rise mostly adopt this temperature model. The constant temperature range of 1S06841 is 170～200℃, and the final temperature of programmed temperature rise is 180～211℃
5 Inspection of chromatogram
5.1 Qualitative analysis
GB5178-85
Figure 4 Typical gas chromatogram of alkylbenzene
A filler, one capillary tube
Use the method of comparing the test chromatogram with the reference alkylbenzene (2.5) chromatogram to identify the components of the sample. 5.2 Quantitative analysis
Use an electronic integrator or a quadrature meter (3.11.3) or paper-cut weighing method to determine the peak area of alkylbenzene with each carbon atom number, and calculate the total peak area.
6 Expression of results
6.1 Calculation method
iThe percentage of the peak area of alkylbenzene to the total peak area is calculated according to formula (1); B, =α,×100
GB 5178-85
The relative molecular weight of alkylbenzene is calculated according to formula (2): M-
The percentage of the peak area of alkylbenzene to the total peak area:
The average relative molecular weight of alkylbenzene
iThe peak area of alkylbenzene:
|Total peak area,
The relative molecular weight of alkylbenzene is shown in the table below.
Number of carbon atoms}Www.bzxZ.net
The average relative molecular weight of sodium alkylbenzene sulfonate can be calculated by adding the calculated average molecular weight of alkylbenzene to the maximum value 1102. 6.2 Precision
The same sodium alkylbenzene sulfonate sample was compared and analyzed in 10 laboratories, and the following statistical results were obtained: Average value (half-average relative molecular weight)
Repeatability standard deviation
Reproducibility standard deviation
Additional notes:
This standard was proposed by the Ministry of Light Industry of the People's Republic of China and technically coordinated by the Daily Chemical Industry Scientific Research Institute of the Ministry of Light Industry. This standard was drafted by the Daily Chemical Industry Scientific Research Institute of the Ministry of Light Industry. The main drafter of this standard was Zhou Luxing.
Instructions for adoption:
1) According to the custom of our country, the carbon atom number of alkylbenzene does not include the carbon atom on the methyl ring, while ISO6 includes the carbon atom on the benzene ring 1, +(2)
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