February 22, 2024

Assay of aspirin: Medicinal Chemistry Practical

Assay of aspirin: Medicinal Chemistry Practical

BP406P Medicinal Chemistry I Practical


To perform Assay of aspirin.


  1. A textbook of Medicinal Chemistry-I,Pragi Arora,Varun Arora,Davinder Kumar,Page no:282,283.
  2. Indian Pharmacopoeia Volume I  1996, Page No:69,70.
  3. Pharmaceutical titrimetric analysis theory and practical,A.A Napoleon,Page No:11-17.


Aspirin, Sodium hydroxide solution (0.5N),Hydrochloric acid (0.5N),Phenol red indicator, Burette, Conical flask, Funnel, Beaker etc.



Weighed accurately 0.75g of Anhydrous sodium carbonate previously heated at 2700C. Dissolve in 100 ml of water and added 0.1ml of methyl red solution. Added the titrant slowly from the burette with constant stirring until the solution becomes faintly pink.

Heated the solution.Cool and continue.If pink colour fades on heating continue this process until a faint pink colour is no longer affected by continous boiling.

Each ml of 0.5M HCl = 0.026495g of Na2CO3


Weighed accurately 1.5g of aspirin and dissolved in 15ml ethanol added 50ml of 0.5M sodium hydroxide boil gently for 10 minutes, cool and titrated the excess alkali with 0.5M HCl using phenol red solution as indicator.

Perform a blank determination the difference between the titration represent the volume of sodium hydroxide consumed.

Each ml of 0.05M NaOH = 0.04504g of C9H8O

What is the best way to assay aspirin?

The best way to assay aspirin is through various methods such as colorimetric analysis, high-performance liquid chromatography (HPLC), UV-VIS spectrophotometry, and spectrophotometric methods. Colorimetric analysis using redox reactions catalyzed by nanoparticles has been validated for the analysis of aspirin concentration in exhaled breath condensate (EBC). HPLC and UV-VIS spectrophotometry methods have been developed for the estimation of aspirin and impurities in aspirin tablets, providing easy and precise measurements. Spectrophotometric methods have also been used for the determination of aspirin, showing good linear correlation and high sensitivity and selectivity. These methods offer reliable and accurate results, making them suitable for research studies, quality control, and routine analysis of aspirin.

What are the different methods used to assay aspirin?

Different methods used to assay aspirin include quantitative analytical methods such as the first derivative of the ratio spectra, TLC densitometry, HPLC, spectrometry, direct titration, back-titration, UV-VIS spectrophotometry, and atomic absorption spectrophotometry.
The first derivative of the ratio spectra was used to resolve the overlapping spectra between aspirin and omeprazole. TLC densitometry technique was applied using TLC aluminum silica gel plates, toluene–acetonitrile–methanol as the mobile phase, and UV detection for the simultaneous quantitative analysis of aspirin and omeprazole. HPLC, spectrometry, direct titration, and back-titration were used in a comparative way to determine the correct amount of acetyl salicylic acid in aspirin formulations. UV-VIS spectrophotometry and atomic absorption spectrophotometry were used for the estimation of aspirin, impurities such as salicylic acid, and heavy metal ions in aspirin tablets.

Second Year B Pharm Notes, Syllabus, Books, PDF Subjectwise/Topicwise

S Y B Pharm Sem IIIS Y B Pharm Sem IV
BP301T Pharmaceutical Organic Chemistry II TheoryBP401T Pharmaceutical Organic Chemistry III Theory
BP302T Physical Pharmaceutics I TheoryBP402T Medicinal Chemistry I Theory
BP303T Pharmaceutical Microbiology TheoBP403T Physical Pharmaceutics II Theory
BP304T Pharmaceutical Engineering TheoryBP404T Pharmacology I Theory
BP305P Pharmaceutical Organic Chemistry II PracticalBP405T Pharmacognosy I Theory
BP306P Physical Pharmaceutics I PracticalBP406P Medicinal Chemistry I Practical
BP307P Pharmaceutical Microbiology PracticalBP407P Physical Pharmaceutics II Practical
BP308P Pharmaceutical Engineering PracticalBP408P Pharmacology I Practical
BP409P Pharmacognosy I Practical

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