Methods of Extraction

Guided by Prepared by
Mrs. Ranjana Ms. Nidhi Mittal
M.Sc. Chemistry
Department of CHEMISTRY

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Extraction:
 Extraction is the method of removing active constituents from a
solid or liquid by means of liquid solvent.
 The separation of medicinally active portions of plant or animal
tissues from the inactive or inert components by using selective
solvents.
 In this method the wanted components are dissolved by the use of
selective solvents known as menstrum & undissolved part is a marc.
After the extraction unwanted matter is removed.
Extracts are prepared by using ethanol or other suitable solvent.
 Extract : Extracts can be defined as preparations of crude drugs
which contain all the constituents which are soluble in the solvent.

Marc: Solid residue obtain after extraction

Menstruum: Solvent used for extraction
Ideal properties of the solvents :
1. Be highly selective for the compound to be extracted.
2. Not react with the extracted compound or with other
compounds in the plant material
3. Have a low price.
4. Be harmless to man and to the environment.
5. Be completely volatile.
6. Should not mix up with water.
7. Should have the big capacity in relation to extractive.
8. The density of solvent should be difference from water
density.
9. Should have the minimum viscosity.
Methods of extraction :
 Infusion
 Decoction
 Digestion
 Maceration
 Percolation
Infusion :
Fresh infusions are prepared
by macerating the crude drug
for a short period of time with
cold or boiling water. These are
dilute solutions of the readily
soluble constituents of crude drugs.
Types of Infusion :
 Fresh Infusion : e.g. Infusion of orange
 Concentrated Infusion : e.g. Concentrated
infusion of Quassia
 FRESH CONCENTRATED
• Only boiled water is added as solvent • First of all we have to take fresh infusion
and heat it to concentrate it then 50-70%
• It has to be used within 12 hrs of its alcohol is added to solution
preparation as there is a cent percent
chance of microbial contamination due to • Saved from any microbial contamination
presence of water and vegetable oils due to presence of alcohol
• Flavours ie. Aroma of the ingredient is • Due to addition of alcohol and evaporation
retained of volatile oils
• Not ready at hand • Aroma is lost
• Ready at hand as it can be stored for long
hours
Decoction :
In this process, the crude
drug is boiled in a specified
volume of water for a defined
time; it is then cooled and
strained or filtered. This
procedure is suitable for
extracting water-soluble,
heat stable constituents.
e.g. Tea , Coffee
 Digestion :
 T h i s is a form of macerationin
which gentle heat is used during
the process of extraction.
 I t is used when moderately
elevated temperature is not
objectionable. The solvent
efficiency of the menstruum is
thereby increased.
e.g. Extraction of Morphine
 • Done by organic solvents {
Alcohol, Acetone, Petroleum}
• So there is less or no chance of
Advantages microbial contamination
• Much faster than Maceration and
Percolation
 Disadvantages

❖ This process is limited to thermo stable drugs

❖ Cannot be applied on thermolabile drugs

❖ It is carried out in Sohxlet apparatus which is costly affair

•
• Purpose of heating is to enhance the solvent power capability to dissolve
substances from application of heat
 Maceration :
In this process solid ingredients
are placed in a stoppered container
with the whole of the solvent and
allowed to stand for a period of at
least 3 days (3 - 7 days) with frequent
agitation, until soluble matter is
dissolved. The mixture is then strained
(through sieves / nets), the marc pressed
and the combined liquids clarified
(cleaned by filtration) or by decantation, after standing.
 Process of maceration :
Plant Material
(Crushed or cut small or Placed in a closed vessels
Moderately coarse powder)

Whole of the selected solvent

Allowed to stand for seven days
shaking occasionally (Menstruum)added

Solid residue (marc)

Liquid strained off pressed(Recover as much as
occluded solution)

Clarified by subsidence or (Strained and expressed

filtration liquids mixed)

Evaporation and Concentration

 MODIFIED MACERATION:-

INTRODUCTION:-
In this type of maceration unorganized drug are used
which have no cellular or tissue structure.
eg. Gum, Resins, Gum-resins, Oleo gum-resins.
Here, unorganized drugs are used because in short time
complete reaction not takes place. Because of no cellular
structure in unorganized drugs, soluble components are
directly exposed to menstrum so the process is quicker.
Here the whole procedure is like simple maceration but
the final product is not collected by pressing the marc but
it is adjusted to the definite volume.

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Simple Modified
➢Done for organized drugs [present ➢Done for unorganized drugs [not
inside the cell] e.g. Cinchona present inside the cell] e.g. Latex,
gum
➢Entire solvent is added at a time
➢Initially we add 80% of solvent at a
➢Retention is more
time and then the rest in
➢We need to express the marc subsequent fraction as per demand
➢We filter the decantated product ➢Subsequent fraction = Vt-Vr/+Vr
➢We never make up the volume Vt= Volume in total
➢Takes longer time from 7-14 days Vr= Volume retained
➢Retention is poor
➢No need to express marc
➢We go for straining
➢Takes 2-7 days
 Merits
▪  Small sample size.
▪  Str ong swelling properties or
high mucilage.
▪  E nergy saving process.

Demerits
•  N o t exhaustively extract the drug.
•  I t is very slow process.
•  Solvent required is more.
Percolation :
• It is continuous downward displacement
of the solvent through the bed of crude
drug material to get extract.

• Most frequently used to extract

active ingredients in the preparation
of tinctures and fluid extracts.

• It is the method of short successive

maceration or process of displacement

• A percolator (a narrow, cone-

shaped vessel open at both ends) conical cylindrical
is generally used.
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Steps in percolation :
 1. Size reduction: The drug to be extracted is subjected to suitable
degree of size reduction, usually from coarse powder to fine
powder.
 2. Imbibition: During imbibition the powdered drug is moistened
with a suitable amount of menstruum and allowed to stand for four
hours in a well closed container.
 3. Packing: After imbibition the moistened drug is evenly packed
into the percolator.
 4. Maceration: After packing sufficient menstruum is added to
saturate the material. The percolator is allowed to stand for 24 hours
to macerate the drug.
 5. Percolation: The lower tap is opened and liquid collected therein
is allowed to drip slowly at a controlled rate until 3/4th volume of
the finished product is obtained.
 Types of Percolation :
1.Simple Percolation :
Drug Percolation and collect
Imbibition Maceration the percolate i.e.3/4th
200gms For 4 hours For 24 hours of the volume of
e.g. i) Tincture of Belladonna finished preparation
ii) Compound tincture of cardamom

2. Modified Percolation :
 Repeated maceration is more effective than simple.
 Multiple maceration – Solvent divided into equal multiple time
considering the solvent retained by plant tissue.
 Used to prepare concentrated preparation.
Reserved percolation:

 In this case the extraction is done through the general

percolation procedure.

 At the last, the evaporation is done under reduced pressure

in equipment like a Climbing evaporator to the consistency
of a soft extract (semi solid) such that all the water is
removed.

 This is then dissolved in the reserved portion which is

strongly alcoholic and easily dissolves the evaporated
portion with any risk of precipitation.
Merits :
✓  Requires less time than maceration.
✓  Extraction of thermolabile constituents can be
possible.

Demerits :
✓  Requires more time than soxhalation.
✓  M o r e solvent is required.
✓  Skilled person is required.
 Conclusion:

EXTRACTION IS
— ESSENTIAL FOR ISOLATION OF EXTRACTION DEPENDS
— ON PROPERTIES OF
DIFFERENT CHEMICAL CONSTITUENT FROM MATERIAL TO BE EXTRACTED. HENCE IT IS
CRUDE DRUG MATERIAL. NECESSARY TO STUDY EXTRACTION METHODS
IN DETAIL.
THANK
YOU