Soxhlet extraction

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2. Percolation
It is continuous downward displacement of the solvent through the bed of crude drug
material to get extract.
Types of percolation
Simple Percolation
Drug
(4 hours)
Imbibitions
(24 hours)
Maceration
Percolation
Modified Percolation
Multiple maceration
Solvent divided into
equal multiple times.
Used to prepare
concentrated
preparations.
Reserved Percolation
A part of
percolate(usually ¾ of vol)
Percolation procedure
continues till the drugs are
exhausted.(Like semi solid)
First portion distillate to
recover the solvent
Mixed both
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3. Continuous Hot Percolation
(Soxhlet Extraction)
Part - A
Distillation flask
 Holds solvent & Extract
Part – B
Thimble
Products
Holder(Crude drugs)
Part – C
Condenser
From vapour to liquid
It basically consist of three parts.
The Soxhlet apparatus allow for
continuous treatment of a sample with
a solvent over a period of hours or days
to extract compounds.
Construction
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4. Assemble/Components
 Electric heater
 Flask
 Drug holder/Thimble
 Condenser
 Inlet pipe
 Outlet pipe
 Stand
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5. Procedure
1) At first the drugs material are wrapped in filter paper or filter cloth.
2) The solid material or crude drugs are placed inside the Thimble(Drug holder).
3) The drugs are placed just below the hole of side tube.
4) Add solvent in the boiling flask. (Also add some pieces of porous pot to
prevent bumping)
5) The solvent is heated by electric heater and gets vapour .
6) The solvent vapour travels up a condenser, and floods into the Thimble
chamber of drug materials.
7) The chamber containing the solid material slowly fills with warm solvent .
Some of the desired compound will then dissolve in the warm solvent.
8) When the soxhlet chamber is almost full, the chamber is automatically
emptied Siphon tube, with the solvent running back down to the distillation
flask
9) The cycle may allowed to repeat many times, over hours or days.
10) If the solvent in siphon tube is colorless, then the complete extraction of
drugs should done.
11) After extraction the solvent is removed, typically by means of a distillation
apparatus or rotary evaporator, yielding the extracted compound.
12) The non-soluble portion of the extracted solid remains in the thimble, and is
usually discarded.
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6. Advantages
 continuous process
 complete extraction should be done
Disadvantages
 time consuming process
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