To perform the assay of Phenobarbitone.

 Experiment

Object:

To perform the assay of Phenobarbitone.

Chemical structure:

Properties:

Molecular Formula: C12H12N2O3

Mol. Wt.: 232.2

Phenobarbitone contains not less than 99.0 per cent and not more than 101.0 per cent

of C12H12N2O3, calculated on dried basis.

Category: 

Sedative, anticonvulsant.

Dose: 60 to 300 mg at night.

Description: Colourless crystals or a white, crystalline powder, odourless.

Assay:

• Weigh accurately about 0.1 g, dissolve in 5 ml of pyridine, add 0.25 ml of thymolphthalein solution and 10 ml of silver nitrate-pyridine reagent and titrate with 0.1 M methanolic sodium hydroxide until a pure blue colour is obtained.
• Repeat the operation without substance under examination.
• The difference between the titrations represents the amount of sodium hydroxide required.

Factor: 

1 ml of 0.1 M ethanolic sodium hydroxide is equivalent to 0.01161 g of C12H12N2O3.

Storage: Store protected from moisture.

Reference:

Dr. Abhishek Tiwari, Dr. Rajeev Kumar " A practical book of medicinal chemistry" Nirali Prakashan Pune 2019 pp 62-63