Definition: removal of soluble material from insoluble
residue either liquid or solid by using liquid solvent.
Methods of
extraction:
1. Distillation: uses a
number solvent for one extract.
2. Expression: uses in green
plant.
3. Infusion:
uses in plant
which have fine tissue by put this plant in hot water for 42hr.
4. Decoction: used in roots
and seeds (boiling).
5. Digestion: this called
maceration but used heat 60
-70
.
6. Maceration: used in the
drug which affect by heat(maceration at 2-5days in 25
-30
)
7. Percolation: extract
amount of active ingredient by uses little of solvent.
Types
of extraction:
1. Liquid-liquid extraction: the solution to be
extracted is brought into contact with another solvent which the solvent is
miscible with the first. The
2. Solid-liquid extraction:
the extraction of soluble constituent from a solid by a solvent
is commonly referred to as leaching. The
Reasons of extraction:
1. Potency is more readily
controlled.
2. Deterioration e.g. by
enzyme action is diminished.
3. Easily preparation of drug
and more stable.
4. Tabling of the crude
material may not be possible.
5. Injection of the crude
material may be undesirable or more dangerous.
6. Smaller bulk facilitates storage and
transport.
Stages
of extraction
processes:
1. Suitable size reduction of
the drug.
2. Penetration of solvent
into the drug.
3. Escape of solution from
the cell.
4. Separation of solution and
exhausted drug.
: Properties of ideal
solvent
a.
Cheap b. Non toxic c. Stable
d. Selective
Example:
1.
Water: used for gum, alkaloid,
salt, glycoside, tannins, water soluble enzymes & small quantity of volatile
oil.
Advantage:
cheap, widely use & non toxic
Disadvantage:
non selective, mould growth & promote hydrolysis.
2. Ethanol: used for alkaloid, volatile oil, resin, color
matter & organic acid.
Advantage: selective, no
mould growth, non toxic at low concentration, natural in reaction &
miscible with water.
Disadvantage: only coast
problem and flammable effect.
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