-
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
The reagents and water used in this standard, unless other requirements are specified, all use analytical reagents that meet the current standards and the third-grade distilled water for laboratory use in GB/T6682 or water of corresponding purity
4.
Measure according to GB/T3143,
4.
Measure according to 2.
The range of densitometer indication is 0.
The sample should be measured at (20±5)℃
4.
Measure according to GB/T7534
4.
Thermometer: local immersion type, temperature range 45~65℃ or 50~70℃, division value 0.
4.
Calculated according to Chapter 6 of GB/T7534-1987, the K value is listed in Table 2
Table 2 K value
4.
Measure according to GB/T6324.
4.
4.
5.
1 Instrument
a) Alkaline burette: 2mL or 1mL, with a division value of 0.
05mL;
b) Pipette: 25mL;
c) Erlenmeyer flask: 100mL
.
4.
5.
2 Reagents and solutions
a) Distilled water: prepared according to GB/T6C3;
b) Sodium hydroxide standard titration solution: c(NaOH)=0.
01mol/L;
c) Phenolphthalein indicator solution: 10g/L
.
4.
5.
3 Analysis steps
In a 100mL conical flask, add 25mL distilled water and 2 drops of phenolphthalein indicator solution , add sodium hydroxide standard titration solution to neutralize to light pink, and then use a pipette to measure 25mL of the sample in a 100mL conical flask, and use hydrogen The sodium oxide standard titration solution is titrated to light pink: the end point is kept for 15s without fading
.
The acidity is expressed by mass percentage X 1 (calculated as acetic acid), calculated according to formula (1):
Where: c— the actual concentration of sodium hydroxide standard titration solution, mol/L;
V— Dosage of sodium hydroxide standard titration solution, mL;
P t — the density of the sample at t℃, g/cm3;
25—The volume of the sample, mL;
0.
060—The mass of acetic acid expressed in grams equivalent to 1.
00mL sodium hydroxide standard titration solution [c(NaOH)=1.
000mol/L] .
4.
5.
4 Allowance
The difference between the two parallel determination results is not more than 0.
0002%, and the arithmetic mean is taken as the determination result
.