Gelatin: Physical and chemical tests / Analysis of crude drugs
Aim: To identify the chemical characteristics of a given sample.
Gelatin occurs in thin sheets, strips or as granular powder. High-grade gelatin light yellow, semi-crystalline substance. It is Odourless and tasteless. In cold water, it swells up and slowly dissolves on warming to form a viscous solution.
- When gelatin is heated with soda lime in a dry test tube, ammonia is evolved due to the presence of the nitrogenous compounds in gelatin.
- Gelatin solution is added to Million’s reagent to give a white ppt, which turns red on heating.
- Gelatin gives buff white ppt with a tannic acid solution.
- Biuret test to 3 ml of test solution of gelatin. NaOH (1ml of 5%) is added whereby white to whitish buff coloured ppt is formed which does not dissolve on heating.
- Yellow ppt. is formed by adding picric acid to a solution of gelatin.
- It gives a yellow ppt. with trinitrophenol in an aqueous solution.
From the above morphological characteristics and chemical tests, the given crude drug is identified as Gelatin.
Kokate CK. Practical Pharmacognosy, 4 edition, VallabhPrakashan. Delhi; 1994: 98
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