0.1 N Sodium Hydroxide Preparation as per USP
Introduction
Sodium hydroxide (NaOH) is a strong base widely used in various pharmaceutical applications, including the preparation of pharmaceutical products, titrimetric analysis, and cleaning of equipment. In the United States Pharmacopeia (USP), a 0.1 N sodium hydroxide solution is specified as a standard solution for various assays and tests. This article outlines the preparation of 0.1 N sodium hydroxide solution as per the USP guidelines.
Materials Required
- Sodium hydroxide (NaOH)
- Distilled water
- Volumetric flask (1 L)
- Balance
- Pipettes
Preparation
Step 1: Weighing of Sodium Hydroxide
Weigh accurately about 4 g of sodium hydroxide (NaOH) using a balance.
Step 2: Preparation of Solution
Transfer the weighed sodium hydroxide to a 1 L volumetric flask. Add about 500 mL of distilled water to the flask and swirl to dissolve the sodium hydroxide.
Step 3: Dilution
Add more distilled water to the flask to make up the volume to 1 L. Mix well to ensure complete dissolution of the sodium hydroxide.
Step 4: Standardization
Standardize the 0.1 N sodium hydroxide solution by titrating it against a primary standard acid, such as potassium hydrogen phthalate (KHP), according to the USP procedure.
Calculation
The normality of the sodium hydroxide solution can be calculated using the following formula:
Normality (N) = ( grams of NaOH / equivalent weight of NaOH ) / liter of solution
where the equivalent weight of NaOH is 40.
Verification
Verify the normality of the prepared 0.1 N sodium hydroxide solution by titrating it against a primary standard acid, such as KHP, according to the USP procedure.
Storage
Store the 0.1 N sodium hydroxide solution in a well-sealed container, protected from light and moisture.
Conclusion
The preparation of 0.1 N sodium hydroxide solution as per the USP guidelines involves accurate weighing, dissolution, and dilution of sodium hydroxide, followed by standardization and verification of the solution. The prepared solution can be used for various pharmaceutical applications, including titrimetric analysis and cleaning of equipment.
