Isolation and detection of Caffeine from tea dust

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Explore Isolation and detection of Caffeine from tea dust with full laboratory guide such as Aim, requirements, principle procedures and result.

Isolation and detection of Caffeine from tea dust

Aim: To isolate and detect the active constituent, caffeine present in tea dust.

Principle:

Caffeine is a purine base (1, 3, 7 – trimethyl xanthine). This is mostly produced from the tea leaves and leaf buds synthetically. As green tea it is available from China and Japan and as black tea from Sri Lanka and India. Leaves are green in colour, apex is blunt. Tea leaves are the rich source of caffeine which is a weak base. Caffeine is present 1-4% in tea leaves while 1-2% in coffee seed.

REQUIREMENTS:

  • Apparatus: Extraction unit, TLC plate, Evaporation unit, Funnel, Test tube, Beaker, Measuring cylinder
  • Chemicals: Lead acetate, H2SO4, Charcoal, Chloroform, Alcohol, Ethanol, MgO, Acetic acid, Silica, HNO3, NaOH, Methanol.

PROCEDURE:

The procedure is depends on two process:

  • Isolation of caffeine from tea dust
  • Detection of caffeine from tea dust

Isolation of caffeine from tea dust

  • Extract Tea leaves (coarse powder form) with boiling water.
  • Filter hot aqueous extract.
  • To precipitate tannin compound, Treat the warm extract sample with lead acetate.
  • Use dilute H2SO4 to precipitate of excess lead acetate present in sample.
  • To remove the coloring matter, boil the filtered sample with charcoal and filter again to remove the charcoal.
  • Extract the filtered decolorized sample again by using chloroform.
  • After evaporation the chloroform extract gives caffeine as a white color material and by using alcohol.
  • In the Soxhlet extractor, we extract the coarsely powdered tea leaves by using ethanol.
  • Use MgO to adsorbs the caffeine present in the extracted sample.
  • Treating the caffeine with 10% H2SO4 will result in its desorption.
  • Finally, use chloroform to extract and re-crystallize the sample.

Detection of caffeine from tea dust

  • Murexide test: Treat caffeine with a few crystals of HNO3 (3-4 drops) in a porcelain dish and subjected to evaporation for drying. Add 2 drops of NaOH solution to the residue, which gives a purple colour1.
  • TLC of caffeine: Dissolve 1 mg of caffeine in 1 ml of methanol or chloroform. Elute the sample by using the solvent (acetate:methanol:acetic acid, 80:10:10) and spot on the TLC plate. The dried plates, when exposed to iodine vapor, exhibit visualization at an Rf value ranging from 0.40 to 0.42.

REPORTS

The active constituent caffeine was isolated and detected from the leaves of tea. It can be used as CNS stimulant, specific analgesic in migraine.

Also read Classification of drugs in pharmacognosy.

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