JNTU B.Pharmacy I Year PHARMACEUTICAL INORGANIC CHEMISTRY-I Previous Question Paper (September/October-2021 - R17)

The history of the Pharmacopoeia reflects the evolution of pharmacy and medicine. The term is derived from the Greek words 'pharmakon' (drug) and 'poiein' (to make). Historically, these books were compiled to provide standardized formulas for the preparation of medicines to ensure consistency and quality.

Early records include the Ebers Papyrus (c. 1550 BC) and the works of Dioscorides, such as De Materia Medica. The first official pharmacopoeia, the Nuovo Receptario, was published in Florence in 1498. The London Pharmacopoeia (1618) was the first to be published under the authority of a national medical body.

In the 19th century, the need for national standardization led to the publication of the United States Pharmacopeia (USP) in 1820 and the British Pharmacopoeia (BP) in 1864. Following independence, India developed the Indian Pharmacopoeia (IP), with the first edition published in 1955, providing official standards for drugs manufactured and marketed in India. Modern pharmacopoeias now focus on analytical methods, purity criteria, and safety standards for pharmaceutical substances.

The limit test for Chlorides is based on the precipitation reaction between chloride ions and silver nitrate in the presence of dilute nitric acid.

Principle: The test relies on the reaction of soluble chlorides with silver nitrate in the presence of dilute nitric acid to form silver chloride, which appears as an opalescence or turbidity in the solution.

Procedure:

1. Take a specific quantity of the test substance and dissolve it in water to form the test solution.
2. In a Nessler cylinder, add 1 ml of dilute nitric acid.
3. Add 1 ml of 0.1 M silver nitrate solution and dilute to the mark with water.
4. Prepare a standard solution using a known amount of chloride (e.g., 0.1 mg of Cl⁻).
5. Compare the opalescence produced in the test solution with that of the standard solution after 5 minutes against a dark background.

Role of Reagents:

• Dilute Nitric Acid: It is added to prevent the precipitation of other acid-soluble anions like phosphates or carbonates by silver ions, ensuring the turbidity is specifically due to silver chloride.
• Silver Nitrate: It acts as the precipitating agent that reacts with chloride ions to form insoluble silver chloride.

If the opalescence in the test solution is less than that of the standard, the sample passes the limit test.