GB/T 2561-1981 Determination of acetone-soluble substances (resin substances) in montan wax GB/T2561-1981 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Determination Method of Acetone-soluble Substances (Resin Substances) in Montan Wax
This method is applicable to the determination of acetone-soluble substances (resin substances) in Montan Wax. GB 2561-81
Method Key Points: The Montan wax sample is extracted with acetone at 18-22°C. The soluble part is centrifuged, and after the solvent is evaporated, it is dried to constant weight. The weight percentage of the acetone-soluble substance (resin substance) is calculated from the weight of the residue after drying. Note: The high selectivity of acetone requires strict temperature control during the determination process. The temperature of acetone should not exceed 0.5°C from the room temperature at the beginning and end of the determination, and should be within the range of 18-22°C. I. Instruments and Reagents
1. Apparatus
(1) Electric centrifuge: speed 3000 rpm; (2) Glass conical centrifuge tube: capacity 10 ml, with No. 1 rubber stopper; (3) Evaporating dish: about 20 mm high, 60 mm in diameter; (4) Measuring cylinder: 10 ml;,Www.bzxZ.net
(5) Tin foil or aluminum foil;
(6) Electric drying oven: capable of maintaining a temperature of 100-110°C; (7) Desiccator,,
(8) Analytical balance: accurate to 0.0002 g; (9) Mercury thermometer: graduation 0.1°C, calibrated in advance. 2. Reagents
Acetone: analytical grade (GB686-78).
II. Determination steps
3. Weigh 0.5 g of lignite wax sample less than 0.1 mm (accurate to 0.0002 g) and place it in a centrifuge tube. Note the temperature of acetone at this time and the room temperature at the beginning of the operation (read to 0.1℃). Add 7 ml of acetone to the centrifuge tube and plug the mouth of the centrifuge tube with a rubber stopper wrapped in aluminum foil. Shake vigorously by hand for two minutes (Note). Note: To minimize the heat of the solvent during shaking, hold the upper edge of the centrifuge tube between the index finger and the middle finger, and press the rubber stopper with the thumb. Wear rubber gloves. The vibration frequency of the hand is about 90 times per minute. The precipitate at the bottom of the test tube must be fully mixed with acetone. 4. Open the rubber stopper and rinse the wax sample adhering to the stopper and the wall of the centrifuge tube with about 1 ml of acetone into the centrifuge tube. Then put the centrifuge tube into the centrifuge for 2 to 3 minutes. At this time, the solution in the tube should be clear. If it is turbid, repeat the centrifugation once. 5. Decant the clear solution in the centrifuge tube into an evaporating dish that has been dried to constant weight at 105℃, and then place the evaporating dish on a water bath to evaporate the solvent.
Note: The temperature of the water bath (using distilled water) should keep the solvent in the evaporating dish at a slow evaporation rate. If the evaporation is too fast, the acetone soluble matter will crawl to the outer edge of the dish, affecting the accuracy of the result. The solvent can also be evaporated with an infrared lamp. 6. The remaining precipitate in the centrifuge tube is further extracted with acetone (repeat the above operation more than 4 times) until the extract is colorless. Issued by the General Administration of Standards of the People's Republic of China
The Ministry of Coal Industry of the People's Republic of China proposed October 1, 1981
Shanxi Coal Chemistry Institute of the Chinese Academy of Sciences
Beijing Coal Chemistry Institute of Coal Science Research Institute
GB 2561-81
Record the room temperature when the operation is completed (read to 0.1℃) 7. Place the evaporating dish after the solvent is evaporated in an electric heating ten-degree drying oven at 100-105℃ for 1-2 hours, then move it into a dryer to cool for 30 minutes, and weigh it (accurate to 0.0002 grams). 8. Dry, cool and weigh for another half an hour until the difference between consecutive weighings is no more than 0.0004 grams. III. Calculation of results
9. The acetone-soluble substance (resin substance) Ac2n in the wax sample is expressed as a weight percentage and is calculated as follows: Ac20 =
Substitute: M-——wax sample weight, grams;
M2~-weight of acetone-soluble substance, grams,
=100+2.5(20-t ）
Other: t=t+t2+t3
-temperature of acetone used during extraction, ℃;
-room temperature at the beginning of the measurement, ℃;
room temperature at the end of the measurement, ℃.
10. Take the arithmetic mean of the results of two parallel measurements as the measurement result. The result is rounded to one decimal place. IV. Allowance
11. The difference between parallel determinations shall not exceed the following provisions: Amount of soluble matter
>30～50
Same laboratory
0.3% (absolute)
0.4% (absolute)
0.5% (absolute)
1.0% of the measured value
Different laboratories
0.5% (absolute)
0.7% (absolute)
0.9% (absolute)
1.8% of the measured value
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