GB/T 2604-1981 Gas chromatography method for determination of o-cresol composition GB/T2604-1981 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China Gas Chromatographic Determination of the Composition of Ortho-Cresol This standard applies to the composition analysis of ortho-cresol prepared from coal tar and phenol-containing wastewater. I. Instruments and Reagents 1. Instruments and Reagents Gas chromatograph: equipped with oxygen flame ionization detector. Chromatographic column: stainless steel tube with a column length of 3 meters and an inner diameter of 1 mm. Micro-injector, 10 micro-open. Analytical balance, sensitivity 0.0001 g. Tray balance: sensitivity 0.01 g. Chromatographic stationary phase: Apizone L. Chromatographic stationary phase: ethylene glycol 20000. Ascorbic acid: analytical grade 6201 Red carrier: acid wash, 40~-60 months. Acetone: analytical grade. Benzene: analytical grade.
O-cresol: no impurities such as phenol, m-cresol and 2,6-cresol, or impurities containing protein. Phenol: not less than 99%.
m-cresol: not less than 99%.
p-cresol: not less than 99%.
2,6-xylenol: not less than 99%. 2. Preparation of column packing
II. Preparation
GB 2604-81
Weigh 0.0200 g of polyethanol-200000 and 0.0750 g of ascorbic acid, place in a 200 ml beaker, add acetone of the same volume as 15 g of the carrier, stir to completely dissolve the stationary liquid (the dissolution speed is slow, it can be heated appropriately on the water, if the solvent evaporates, it should be replenished), weigh 15.0 g of 6201 carrier and add it to the solution, mix. Stir occasionally to evaporate all the droplets. Dry in a drying oven at 100°C. Add 1.95 g of Avosone L, an equal volume of the above carrier, and dissolve all the stationary liquid under stirring. Add the above dried and coated carrier to the solution and mix. Allow the droplets to evaporate completely without moving. Dry in a drying oven at 100°C for later use. 3. Filling and aging of the chromatographic column
Tightly pack the prepared filler into the clean and dry column arm under vibration, seal both ends with glass wool, install the filled chromatographic column in the chromatograph, pass a small flow of carrier gas, and age at 160°C for about 4 hours to stabilize the baseline. 1. Standard sample PreparationwwW.bzxz.Net
Accurately weigh 5 portions of o-cresol reagent, each about 10 grams, and then accurately weigh different amounts of phenol, m-cresol (m-cresol and p-cresol are mixed in a weight ratio of 2:1) and 2,6-diphenol, so that the content of each impurity component varies between 0.2% and 2%. Mix the standard sample thoroughly. The State Administration of Standardization issued
The Ministry of Metallurgical Industry of the People's Republic of China proposed to be implemented on January 1, 1982
The Meishan Engineering Command drafted
and then used for standby.
5. Adjustment of operating conditions| |tt||GB2604-81
The table below lists typical operating conditions, which may be adjusted appropriately according to actual conditions to meet the following requirements: (1) The relative separation R value of m-cresol and o-cresol must meet the following requirements; ±, same pair + t, + get
+ · same pair, + y + {all,
wherein R-
y (m-cresol·
-relative separation, the value should be greater than 1.80
m-cresol retention value, mm:
o-cresol Retention value of phenol, mm:
-~ Peak width of m-cresol, mm;
Half peak width of o-cresol, mm.
(2) The injection volume and the sensitivity of the instrument should be controlled within the linear response range of the peaks of phenol, m-cresol and 2,6-dimethylphenol. The peak height of m-cresol with a content of 1% should not be less than 20 mm. Typical operating conditions
National standard liquid
Chromatographic column
Detector temperature
Vaporization temperature
Column head pressure
0.13 % ethylene glycol-20000 + 0.5% ascorbic acid + 13% apicone L
6201 red carrier, acid-washed, 4060 months
3 meters long, 4 mm inner diameter
130°C
150°C
270°C
0.8 kg/cm2
6. Drawing of standard curve
Detector
Jinxiang#
o-cresol
m-p-cresol
2,6-dimethylphenol
Hydrogen flame ionization detector
1~2 microliters
Relative retention value
Put the standard sample in a water bath at about 50C to make it completely melt and shake it well. Adjust the operating conditions of the chromatograph. Use a micro syringe to accurately inject a certain amount of standard sample. Each standard sample is injected at least once. After the chromatogram is obtained, the peak height of each impurity component is measured according to the method shown in the figure. Three standard curves are drawn with the content of each impurity component versus the average peak height. o-methyl
m+P-cresol,
Time (min) 13
GB2604—81
Three analysis steps
7. Adjust the operating conditions of the instrument to the time of making the standard curve, so that the retention time of each impurity component is also the same as that when making the standard curve. After the sample is melted and mixed in a water bath at about 50℃, inject the sample with the same amount as the sample when making the standard curve. After obtaining the color chart, measure the peak height of each impurity component according to the method shown in the figure. The relative deviation of the peak height measured by two parallel tests should not be greater than 5%. According to the average peak height of each impurity component, the content is obtained from the corresponding standard curve.
4. Calculation
B, o-cresol content (X)% is calculated as follows: Calculation
Xa=100-EX,
Wherein: X——weight percentage of o-cresol, %; X——weight percentage of impurity components, %. 5% error
9, error of parallel tests in the same laboratory: 2,6-dimethylphenol does not exceed 0.10%, and o-cresol does not exceed 0.30%.
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