Assay of Dapsone
BP607P Medicinal Chemistry III Practical: I Preparation of drugs Sulphanilamide * 7-Hydroxy, 4-methyl coumarin * Chlorobutanol * Triphenyl imidazole * Tolbutamide * Hexamine II Assay of drugs Isonicotinic acid hydrazide * Chloroquine * Metronidazole * Dapsone * Chlorpheniramine maleate * Benzyl penicillin III Microwave irradiation technique Synthesis of Phenytoin by Microwave * Synthesis of Aspirin by Microwave IV Drawing structures and reactions using chem draw®
Aim:
To determine the percentage purity of a given sample of the tablet.
Principle:
Dapsone is a diamino diphenyl sulphone. It is assayed by direct diazotization titration. The free primary amino group present in dapsone is diazotized by nitrous acid and hydrochloric acid to form arene diazonium compound. The end point can be determined by using external indicator i.e. starch iodide paper, during titration with sodium nitrite an aromatic primary amine is diazotized.
After the end point the drug solution containing a slight excess of nitrite comes in contact with starch iodide paper. It oxidizes iodide into iodine which gives blue colour with starch indicating the end point.
Reaction:
Procedure:
Preparation of 0.1M Sodium nitrite solution:
7.5g of sodium nitrite was dissolved in sufficient water to produced 1000ml.
Standardisation of 0.1M Sodium nitrite:
0.3g of sulphanilic acid was dissolved in 50ml of 2M hydrochloric acid, 3g of potassium bromide was added, cool in ice and titrate with 0.1M sodium nitrite solution using starch iodide paper as external indicator.
Each ml of 0.1M Sodium nitrite= 0.01732g of C6H7NO3S.
Assay of Dapsone tablet:
20 tablets were weighed and powered. Tablet powder equivalent to 0.25gm dapsone was weighed and dissolved in a mixture of 15ml of 2M hydrochloric acid.
The solution was cooled to about 15oC and carry out sodium nitrite titration using starch iodide paper as an external indicator.
The endpoint is immediate appearance of blue colour.
Each ml of 0.1M sodium nitrite= 0.01241g of C12H12N2O2S.
Report:
The Molarity of 0.1M sodium nitrite=
The percentage purity of given dapsone tablet was found to be=
Third Year B Pharm Notes, Syllabus, Books, PDF Subjectwise/Topicwise
Suggested readings
Recommended readings: