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Testing Procedure (Method of analysis) for Acetates, Acetyl Groups and Alkaloids


Learn how to identify the Acetates,Acetyl Groups and Alkaloids.

Acetates

A. Heat the substance under examination with an equal quantity of oxalic acid; acidic vapours with the characteristic odour of acetic acid are liberated.
B. Warm 1 g of the substance under examination with 1 ml of sulphuric acid and 3 ml of ethanol (95 per cent); ethyl acetate, recognisable by its odour, is evolved.
C. Dissolve about 30 mg of the substance under examination in 3 m1 of water or use 3 ml of the prescribed solution, add successively 0.25 m1 of lanthanum nitrate solution, 0.1 ml of 0.1 M iodine and 0.05 m1 of dilute ammonia solution. Heat carefully to boiling, within a few minutes a blue precipitate or a dark blue colour is produced.

Acetyl Groups

In a test-tube (about 180 mm x 18 mm) place 10 to 20 mg or the prescribed quantity of the substance under examination and add 0.15 ml of phosphoric acid. Close the tube with a stopper through which passes a small test-tube (about 100 mm x 10 mm) containing water to act as a condenser. On the outside of the smaller tube, hang a drop of lanthanum nitrate solution.
Except for substances hydrolysable only with difficulty, place the apparatus in a water-bath for 5 minutes and remove the smaller tube. Mix the drop with 0.05 ml of 0.01 M iodine on a porcelain tile or glass slide and then add one drop of 2M ammonia at the edge of the mixed drop; after 1 or 2 minutes a blue colour is produced at the junction of the two drops and the colour intensifies and persists for a short time.
For substances hydrolysable only with difficulty, heat the mixture slowly to boiling point over an open flame instead of using a water bath.

Alkaloids

Dissolve a few mg or the prescribed quantity of the substance under examination in 5 ml of water, add dilute hydrochloric acid until the solution has an acid reaction and then add 1 m1 of potassium iodobismuthate solution; an orange or orangered precipitate is formed immediately
Ankur Choudhary is India's first professional pharmaceutical blogger, author and founder of Pharmaceutical Guidelines, a widely-read pharmaceutical blog since 2008. Sign-up for the free email updates for your daily dose of pharmaceutical tips.
Email: .moc.enilediugamrahp@ofni Need Help: Ask Question


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