Isolation & identification of atropine & Quinine

Isolation & identification of Atropine


Isolation: 

  1. Moisten the powdered bark with an aqueous solution of sodium carbonate and extract it with ether or benzene. The free alkaloids are extracted from the solvent and acidified with acetic acid. Discard the aqueous layer.
  2. Add sodium hydroxide to the organic layer to precipitate atropine sulfate. Filter, recrystallize, and purify the crystals with activated charcoal.
  3. Dissolve the atropine sulfate in dilute sulfuric acid and make it alkaline with ammonia. Atropine will precipitate as crystals. Wash and dry them at 45-55°C.


Identification: 

Vitali-Morin Test:
  • Atropine + Small Amount of Con. HNO3 
  • Evaporated to dryness in Waterbath.
  • Residue is dissolved in 1 ml Acetone and few drops of freshly prepared Alcoholic KOH, 
  • Observation: Violet Colour (Tropane Neuclus) 

Isolation & identification of Quinine 

Isolation 


Here are some steps for isolating quinine from cinchona bark:
  • Mix the powdered bark with calcium hydroxide or calcium oxide and sodium hydroxide solution. Let it stand for a few hours.
  • Extract the alkaloids with benzene in a Soxhlet apparatus. 
  • Filter the benzene extract and add sulfuric acid to separate the aqueous and organic layers. Discard the benzene layer.
  • Add sodium hydroxide to the aqueous layer to precipitate quinine sulfate. Filter, recrystallize, and purify the crystals with activated charcoal.
  • Dissolve the quinine sulfate in dilute sulfuric acid and make it alkaline with ammonia.
  • Quinine will precipitate as crystals. Wash and dry them at 45-55°C.


Identification 


  • Thalleoquin Test:
    • Bromine Water and Ammonium solution is added to a small amount of Sample 
    • Emerald Green colour confirms the presence of Quinine. 

  • Thin layer chromatography (TLC): Quinine can be separated and identified by TLC using silica gel as the stationary phase and pure chloroform as the mobile phase. Quinine shows three spots for the free drug and two metabolites under UV light. The Rf value of quinine is 0-0.1.

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