-
Categories
-
Pharmaceutical Intermediates
-
Active Pharmaceutical Ingredients
-
Food Additives
- Industrial Coatings
- Agrochemicals
- Dyes and Pigments
- Surfactant
- Flavors and Fragrances
- Chemical Reagents
- Catalyst and Auxiliary
- Natural Products
- Inorganic Chemistry
-
Organic Chemistry
-
Biochemical Engineering
- Analytical Chemistry
- Cosmetic Ingredient
-
Pharmaceutical Intermediates
Promotion
ECHEMI Mall
Wholesale
Weekly Price
Exhibition
News
-
Trade Service
4 Test method
Unless otherwise specified, only reagents confirmed to be analytically pure and grade 3 water in compliance with GB/T6682-2008 are used in the analysis
4.
Under natural light or fluorescent light, visually observe the sample taken
4.
4.
Titrate the sample with a standard sodium hydroxide titration solution, use phenolphthalein as an indicator, and calculate the content in terms of maleic anhydride
4.
4.
4.
4.
Weigh 1g laboratory sample, accurate to 0.
4.
The mass fraction w 1 of maleic anhydride ( calculated as C 4 H 2 O 3 ) , the value is expressed in %, calculated according to formula (1):
Where:
V—The value of the volume of the standard titration solution (4.
c—The exact value of the concentration of sodium hydroxide standard titration solution, the unit is moles per liter (mol/L);
m—The value of the mass of the sample, in grams (g);
M — The value of the molar mass of maleic anhydride (1/2C 4 H 2 O 3 ), in grams per mole (g/mol[M=49.
Take the arithmetic average of the two parallel determination results as the determination result, and the absolute difference between the two parallel determination results shall not exceed 0.
4.
3 Determination of melting color
Carry out according to the method specified in GB/T3143-1982
.
In the determination, take an appropriate amount of laboratory samples in a 50mL colorimetric tube and heat it on a water bath at (65±2)℃ (to avoid water vapor intrusion)
.
After the sample is melted, immediately adjust the sample volume to the mark, and observe the axial day
.
4.
4 Determination of crystallization point
Carry out according to the method specified in GB/T7533-1993
.
The weighing amount is about 35g
.
The range of the main thermometer is (40~70)℃, the length is (30~35)cm; the subscale is 0.
1℃
.
The heating bath is (65±2)℃ constant temperature water bath
.
4.
5 Determination of residue on ignition
Carry out according to the method specified in GB/T7531-2008
.
Weigh 50g, accurate to 0.
01g
.
Burning temperature (650±25)℃
.
The absolute difference between the two parallel determination results is not more than 20% of the arithmetic mean of the two determination values
.
Keep the residue in the crucible for iron content determination
.
4.
6 Determination of iron content
4.
6.
1 Analysis steps
Add 3 mL of hydrochloric acid to the residue obtained in 4.
5 , place it on a water bath and heat to dissolve the residue, and let the solution become nearly dry.
After cooling, dissolve it with water and transfer it to a 100 mL volumetric flask
.
The following operations are carried out in accordance with the provisions of GB/T30492006
.
4.
6.
2 Result calculation
The mass fraction w2 of iron (calculated as Fe), the value is expressed in ug/g, calculated according to formula (2):
Where:
m 1 —The value of the mass of iron found on the standard curve corresponding to the absorbance of the sample, in micrograms (ug);
m 2 —The value of the mass of the sample, in grams (g)
.
Take the arithmetic mean of the two parallel determination results as the determination result, and the absolute difference between the two parallel determination results shall not be greater than 20% of the arithmetic mean of the two determination values
.
Related Links: Maleic Anhydride for Industrial Use (1)