2. Aim To Perform Assay of Aspirin Tablet
What is mean by Assay:
• An assay is an investigative (analytic) procedure for qualitatively assessing or quantitatively measuring the
presence, amount, or functional activity of a target entity (the analyte).
Different Types of Assay:
• As is Basis: The expression denotes analysis of the product as it is received. The sample is analyzed directly
without any drying.
• Dried Basis: The sample received is pulverized to a fine powder is dried before being weighed out to prepare
the sample solution. This process is performed by heating to 105° to 120°C for specified time and drying in a
desiccator to constant weight
• Anhydrous Basis: Anhydrous basis implies that there is no water present in the material before analysis is
performed. It means that the sample does not have any absorbed water or bound water such as hydrates.
Different Types of techniques:
• HLPC, GC, Titrations, UV, IR.
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3. Aim To Perform Assay of Aspirin Tablet
Requirement.
• Chemical: Aspirin, Sodium hydroxide
solution, hydrochloric acid, Phenol red
indicator
• Glassware: Burette, conical flask, funnel,
beaker, Etc.
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4. Aim To Perform Assay of Aspirin Tablet
Aspirin also knows as Acetyl salicylic acid
Aspirin molecular formula:
• C9, H8O4.
Molecular weight:
• 180.16 g/mol
Category/ Uses:
• Analgesic, Antipyretic, Antirheumatic.
Description:
• colorless, crystals or white crystalline powder, odorless or almost odorless.
Solubility:
• freely soluble in ethanol soluble in chloroform and in ether, slightly soluble in water.
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5. Aim To Perform Assay of Aspirin Tablet
Principal:
• Aspirin is estimated by Acidimetric titration.
Its determination depends upon alkaline
hydrolysis of aspirin to acetic acid and
salicylic acid followed by back titration of the
excess alkali using phenol red as an indicator.
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6. Aim To Perform Assay of Aspirin Tablet
Reaction Machanism:
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7. Aim To Perform Assay of Aspirin Tablet
The difference between the titration, represents the amount of sodium hydroxide required.
Repeat the operation without the substance being examined (Blank)
Titrate, the excess of alkali with indicator
Add 30 mL of 0.5 molar sodium hydroxide boil gently for 10 minute and cool.
Weigh accurately quantity of powder equivalent to about 0.5 gram of Aspirin
Extraction of Aspirin, weigh and powder 20 tablets
Procedure:
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8. Aim To Perform Assay of Aspirin Tablet
So factor is each mL of 0.5. Molar Sodium hydroxide is required to 0.04504 g of C9H8O4.
0.04504g of Aspirin = 1ml of 0.5N NaOH
45.05 g of Aspirin = 1000ml of 0.5N NaOH
90.08 g of Aspirin = 1000ml of 1N NaOH
90.08 g of Aspirin = 1 moles of NaOH
180.16 g of Aspirin = 2 moles of NaOH
1 mol pf Aspirin = 2 moles of NaOH
Factor calculation:
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9. Aim To Perform Assay of Aspirin Tablet
Calculation:
Sr. No Vol. of 0.5M HCL
required for Sample
titration
Vol. of 0.5M HCL
required for Sample
titration
1 19 30
2 20 30
3 19 29
Average 19.33 29.66
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10. Aim To Perform Assay of Aspirin Tablet
=93%
= 0.4653/0.5 × 100
% Purity= Calculated value of Aspirin/ Wt. of Aspirin × 100
Therefor 10.33 × 0.04504 = 0.4653
Total vol of 0.5 M HCL = 29.66-19.33= 10.33ml
Total volume of 0.5 M HCL required= Avg of Blank- Avg of Back
Means 1 ml of 0.5M HCl = 0.04504 g of C9H8O4.
Each mL of 0.5. Molar Sodium hydroxide is required to 0.04504 g of C9H8O4.
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