Preparation and standardization of 0.5 N Sulfuric acid USP Volumetric Solution
Add slowly, with stirring, 13.5 mL of Sulfuric acid to a sufficient quantity of water to make 1000 mL.
Accurately weigh about 2.5 g of Tromethamine, previously dried at 105°C for 3 hours. Dissolve in 50 mL of water, and add 2 drops of Bromocresol green TS. Titrate with 0.5 N Sulfuric acid to a pale yellow end point.
Each 121.14 mg of Tromethamine is equivalent to 1 mL of 1 N Sulfuric acid.
Normality (N) = [Weight of Tromethamine (in g)]/[0.12114 x Titration Reading (in ml)]
Limit: 0.5 N ± 5 % (0.4750 N – 0.5250 N)
3. PREPARATION OF INDICATORS / REAGENTS:
a. Bromocresol green TS:
Dissolve 50 mg of Bromocresol green in 100 mL of alcohol and filter if necessary.
4. STORAGE CONDITION:
Store in glass-stoppered bottles.