GB/T 2601-1981 Gas chromatography method for determination of composition of phenolic products GB/T2601-1981 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Gas chromatographic determination method for the composition of phenolic products GB 2601-81
This standard is applicable to the determination of phenol, o-cresol, m-cresol and p-cresol in tri-cresol and m-p-cresol of coking products. This method uses PBOB liquid crystal as stationary liquid, phosphoric acid as tailing agent, and white 405 silanized carrier as stationary phase. The sample does not need to be converted, and is directly injected, separated, and analyzed for components such as cresol isomers. The front area of ​​each component is measured. The percentage of each component is calculated by area normalization method.
Only for testing
1. Instruments and reagents
Chromatograph: Any chromatograph with the following technical characteristics. (1) Hydrogen flame ionization detector, with a sensitivity better than 10-\g/s (benzene). (2) Recorder, the range is 0~~1, 0~5, 0~10 millivolts, (3) Chromatographic column: 2~4 meters long, stainless steel tube or glass tube with an inner diameter of 3 meters, (4) Nitrogen (nitrogen): purity greater than 99%. (5) Hydrogen, purity greater than 99%.
(6) Purified air,
(7) Syringe: a 10 microliter micro syringe: a 0.25~1.0 ml medical syringe. Tray balance, sensitivity 0.1 g,
Analytical balance, sensitivity 0.0001 g,
Chromatographic stationary liquid: PBOB liquid crystal. The liquid crystal phase temperature range is 120 (122) 124 (126) 193 (195). Phosphoric acid: analytical grade, should comply with the provisions of GB1282-77 "Phosphoric Acid". Carrier: White 405 silanized carrier, 80-100 mesh, carriers with similar performance are allowed. Methanol, analytical grade, should comply with the provisions of GBB83-78 (Methanol). Anhydrous ethanol: analytical grade, particles comply with the provisions of GB678-78 "Anhydrous ethanol". Methylene dichloride: analytical grade.
Phenol, purity greater than 99.0%.
O-cresol: purity greater than 99.0%.
M-cresol, purity greater than 9.0%,
P-cresol: purity greater than 99.0%.
2,3-Dimethylphenol: purity greater than 99.0%,
2,4-dimethylphenol: purity greater than 99.0%. 2,5-dimethylphenol, purity greater than 99.0%.
2,6-diphenol: purity greater than 99.0%.
3,4-dimethylphenol: purity greater than 99.0%. 3,5-dimethylphenol, purity greater than 99.0%.
Ministry of Metallurgical Industry of the People's Republic of China
January 1, 1982
Tangshan Thermal Energy Research Institute
Gong, purity greater than 99.0%
2,3,5-trimethylphenol; purity greater than 99,0%. 2,4,5-trimethylphenol: purity greater than 99.0%. 2,4,6-trimethylphenol: purity greater than 99.0%, 3,4,5-trimethylphenol: purity greater than 99.0%, o-ethylphenol; purity greater than 99.0%.
m-ethylphenol: purity greater than 99.0%.
p-ethylphenol: purity greater than 99,0%.
GB2601--81
II. Preparation
2. Preparation of chromatographic column (taking a chromatographic column with an inner diameter of 3 mm and a length of 2 meters as an example) Weigh 0.04 g of phosphoric acid, add an equal volume of methanol to 8 g of the carrier to dissolve, transfer to evaporating blood, pour 8 g of 405 silanized carrier into it, slowly stir and dry under infrared light. Weigh 0.52 g of PBOB liquid crystal, add it to evaporating III, add an equal volume of dichloromethane to 8 g of the carrier, wait for gold quenching, add the carrier coated with phosphoric acid to the solution in the evaporating solution, and stir at 4 Stir and dry slowly at 0-50℃ or room temperature. When there is no methane smell, you can install the column. 3. Aging of the chromatographic column
The prepared chromatographic column is aged at 150℃ with carrier gas for 8-16 hours. 4. The separation R value of the column for 4- and 6-phenol must meet the following requirements. R=bzxZ.net
-relative separation, the value should be greater than 1.0;
wherein. R-
retention value of 6-phenol, mm;
retention value of 6-cresol, mm;
\± half of p-cresol Peak width, mm: Half peak width of m-cresol, m,
)+(m)
, the relative separation R value of 2,6-dicresol and o-cresol (or m-cresol) should also be greater than 1.0. 5. Dilution of sample
Take about 0.5 ml of mixed cresol sample, add 5 ml of anhydrous ethanol, dilute and wait for analysis. III. Analysis steps
6. Typical conditions for chromatographic separation
Detector: hydrogen flame ionization detector (upper 100 type), stationary liquid: 6.5% PBOB liquid crystal.
Phosphoric acid, 0.5%.
Carrier: white 405 silanized carrier (80~100 mesh), inner diameter of chromatographic column: 3 mm.
Chromatographic column length: 2 meters.
Column chamber temperature: start up and heat to 136℃, and drop to 114℃ after 1 hour. Detector temperature, 200℃
Vaporization chamber temperature, 270℃.
Outlet temperature: 200℃,
Nitrogen flow rate: 18 ml/min.
Hydrogen flow rate: 30 ml/min.
Air flow rate: 500 ml/min,
Recorder paper speed: 0.5 cm/min.
Input high resistance: 10\ megohms,
Attenuation gear: ×1/8.
Injection volume: 0.2~0.6 μl.
GB2601--81
Note: After the chromatographic column is stopped, such a heating and cooling process must be carried out every time the machine is turned on. 7. Under the condition of meeting the requirements for separation degree R in Article 5, it is allowed to adjust the operating conditions appropriately. 8. Start the chromatograph according to the chromatographic separation conditions, and after the instrument is stable, take the diluted sample for analysis. The chromatograms of the analysis of tri-cresol and m-cresol are shown in Figure 1 and Figure 2 respectively. The relative retention values ​​of the components of the obtained phenolic products are shown in Table 1.60
Time (min)
Time (min)
1—Ethanol, 2—Phenol*3—O-formaldehyde, 4—2,6-dimethylphenol, 5—m-cresol, 6~p-cresol, 7—2,4-dimethylphenol, 2,5-dimethylphenol, 8-Benzene, 9—2,3-dimethylphenol.3,5-dimethylphenol, 10—X (ethylphenol) 113,4-dimethylphenol sequence
GB2601—81
Relative retention values ​​of phenolic product components under typical separation conditions (, phthalic anhydride) Relative retention values ​​of cresol
2,6-dimethylphenol
m-cresol
p-cresol
2,4-dimethylphenol, 2,5-dimethylphenol
2,3-dimethylphenol. 3,5-dimethylphenol
X(methylphenol)
3,4-dimethylphenol
2,3,5-trimethylphenol
IV. Calculation
9. Correction factor adopts the weight plate correction factor. Sample
m-cresol
woncresol
Take phenol as the reference substance, prepare a mixed phenol standard sample with a total weight of about 0.5-1.0 g according to the proportion range of the content of each component in the tri-cresol and m-cresol products?, dilute it 4-8 times with anhydrous ethanol, inject 0.2-0.6 microliters, measure the elution front area of ​​each component (peak height multiplied by half peak width), and the correction factor is calculated as follows: ft-
Wherein, hand
—i Weight correction factor of component:
—1 Weight of component?, g:
Weight of reference substance phenol, g:
A:—i Component elution peak area, mm\: As Peak area of ​​reference substance phenol, mm*, m.×As
ms×A:
Note ① According to the requirements of mathematical statistics, when determining the correction factor 1:, the degree of freedom must be greater than 25, so 8 to 9 warm cresol standards need to be prepared, Each standard sample needs to be measured in parallel 4 to 5 times. The f of 1 component is measured from each standard sample, and the average value is taken as the correction factor of the component. ② This weight should be converted into actual standard quantity according to its purity. The content of each component in the 10 sample, C, (weight)%, is calculated by area normalization method according to the following formula: C,
wherein, f—component weight correction factor;
A.—*component elution peak area, mm\; fXA,
St,xA,
N——The number of components in the sample.
Note: The measurement of the peak area adopts the peak height and half peak width method, x100
GB2601-81
V. Division
11, the error of parallel tests in the same laboratory is shown in Table 2. Components,
《Weight）
Phenol (<20)
O-cresol (<35)
Me-cresol (30~60)
P-cresol (<35)
Not more than
Not more than
Not more than
Not more than
Error basis,
(Dong)
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