Extraction Process and Techniques

1. EXTRACTION
Dr: Fatehalrahman Magbool, PhD
Assist. Professor of Pharmaceutics

2. Definition
• Extraction is the first step to separate the desired natural
products from the raw materials.
• The process of isolation of active ingredients or active
substances or active medicaments from raw materials of
either plants or animals or directly from the natural sources
with the help of solvent is called extraction.
• In Extraction the mixture of substances is dissociated, by
dissolving each component with one or other solvents which
yields two phases – Raffinate Phase (rich in Feed Solvent)
and Extract Phase (rich in Solute)

3. General Terms
• Marc:
• The unwanted or insoluble substances left behind after the
process of extraction is called marc. These are not used for
further purpose in the process of extraction.
• Menstrum
• The solvent used in the process of extraction is called
solvent. The most commonly used menstrum is water.

4. Objectives of Extraction
• To obtain the therapeutic portion of dosage form from raw
materials and to eliminate the unwanted or inert material by
treatment with solvent.
• They play a decisive role in the determination of qualitative
and quantitative composition of extracts.
• The extracts obtained are also utilized for the isolation and
characterization of therapeutically active chemical
constituents.

5. Extraction Types
• Liquid-Liquid Extraction
• Solid-Liquid Extraction

6. Liquid-Liquid Extraction
• Solution of substance is brought into contact with another
solvent for the substance that is immiscible with first
solvent
• A concentration gradient is set up between the phases and
mass transfer will occur until an equilibrium is established
• As the process is controlled by mass transfer the liquid
must be thoroughly mixed to give a large enough surface
area for contact sufficient time must be allowed in the
dispersed for equilibrium to be set up
• The liquid are separated

7. Solid-Liquid Extraction
• Extraction of soluble constituents from a solid or semi-solid
by means of suitable solvent
• Examples:
• Extraction of fixed oils from seeds
• Preparation of alkaloids
• Isolation of hormones

8. Extraction Methods
• include solvent extraction, distillation method, pressing and
sublimation according to the extraction principle.
• Solvent extraction is the most widely used method.
• The extraction of drug progresses through the following
stages: (1) the solvent penetrates into the solid matrix; (2)
the solute dissolves in the solvents; (3) the solute is
diffused out of the solid matrix; (4) the extracted solutes
are collected.

9. Factors Affecting Extraction
• Any factor enhancing the diffusivity and solubility in the
above steps will facilitate the extraction.
• The properties of the extraction solvent.
• The physicochemical properties of drug.
• The particle size of the raw materials.
• The solvent-to-solid ration.
• The extraction temperature.
• The extraction duration.

10. • The physical properties which effect the drug extraction
are:
1. Gravitation 2. Diffusion 3. Osmosis 4. Adhesion
5. Capillarity 6. Convection 7. Solubility 8. Surface tension
• Wetting property of solvent can be improved by displacing
the air entrapped in the capillaries and also by using surface
active agent. Surfactant can increase the solubility by
means of solubilization.

11. • The selection of the solvent is crucial for solvent
extraction.
• Selectivity, solubility, cost and safety should be considered
in selection of solvents.
• It should also be have a low viscosity, not inflammable and
chemically and physically inert.
• Based on the law of similarity and intermiscibility (like
dissolves like), solvents with a polarity value near to the
polarity of the solute are likely to perform better and vice
versa.

12. • The main solvents used in the process of extraction are:
• 1. Water
• 2. Alcohol
• 3. Ether
• 4. Chloroform
• 5. Light petroleum

13. • Advantages Water as Solvent
i. It is very cheap
ii. It has wide solvent action
iii. It is non-toxic
iv. It is inflammable
• Disadvantages Water as Solvent
i. Microbial contamination will occur
ii. It is non-selective
iii. It promotes hydrolysis
iv. It also promotes enzymatic degradation

14. • Advantages of Alcohol
1. Has wide solvent action
2. No chance for the bacterial growth
3. It is non-toxic
4. Neutral in nature and also show compatibility with the
pharmaceutical product
5. Absorption of constituents is more than water
6. It is selective
7. No additional preservatives were required
8. Requires less heat when compared to water
• Disadvantages of Alcohol
1. It is costly

15. • Advantages of Ether
a. It is inflammable
• Disadvantages of Ether
a. It is costly
b. It has a physiological effect
c. It is unsuitable for internal administration.

16. • Advantages of Chloroform
a. it is inflammable
• Disadvantages of Chloroform
a. It is costly
b. It has a physiological effect
c. It is unsuitable for internal administration.

17. • Advantages of Light Petroleum
a. It is inflammable
• Disadvantages of Light Petroleum
a. It is costly
b. It has a physiological effect
c. It is unsuitable for internal administration

18. The Conventional Extraction
Techniques
• The Conventional Extraction Techniques
Extraction
process
infusion decoction maceration percolation digestion
Fresh infusion concentrated
Simple
maceration
Maceration
With
adjustment
Multiple
maceration
Simple
percolation
Percolation for
concentrated
preparation
Continuous
percolation

19. The Conventional Extraction Methods
1. Infusion
pouring of water over the drugs and then allowing it to
keep in contact with water for the stated period , usually 15
minutes, with occasional stirring and finally filtering off the
liquid.
• The marc is not pressed .
• The boiling water is commonly used as a solvent

20. • There are two types of infusion
• a. Fresh infusion
• Afresh infusion is an aqueous solution of active
constituents of vegetable drug prepared by the process of
infusion.
• Coarse powder of drug is used in the preparation of
infusion.
• Water used as menstrum ( because it has more penetration
power and dissolves the active constituents of the drug ).
• Pharmacopoeia states that fresh infusion should be used
with in 12 hours after its preparation because it gets
spoiled due to fungal or bacterial growth.

21. b. concentrated infusion
• Concentrated infusions are prepared by double or triple
maceration process.
• Concentrated infusions are eight times stronger than the
fresh infusion.
• Alcohol in the concentration of 20 – 25% is used as
menstrum. Hence these preparations can be stored for a
longer period due to preservative action of alcohol.

22. 2. Decoction
• In this process , the drug is boiled with water for stated
period usually10 minutes. After boiling, the liquid is
strained and water is passed through the content of the
strainer to make the required volume.
• This process is mainly used for vegetable drugs of hard and
woody nature having thermos table water soluble
constituents.
• The extract from decoction contains a large amount of
water-soluble impurities. Decoction cannot be used for the
extraction of thermolabile or volatile components.

23. 3. Maceration
• This is a very simple extraction method with the
disadvantage of long extraction time and low extraction
efficiency.
• It could be used for the extraction of thermolabile
components.
• The various types of maceration process are:
• a. simple maceration
• In this process the drug is placed with the whole of the
menstrum in a closed vessel for seven days. During this
period shaking is done occasionally. After seven days , the
liquid is strained and marc is pressed.

24. • The expressed liquid is mixed with strained liquid . It is
then filtered to make a clear liquid . The final volume is not
adjusted .
• Example: The tinctures made by simple maceration are:
• (1) Tincture of orange .
• (2) Tincture of lemon.
• b. maceration with adjustment
• A process for tinctures made from un organized drugs such
as oleo resins and gum resins . This process is known as
(maceration with adjustments), Example of the tinctures
made by maceration with adjustment are: compound
tinctures of benzoin.

25. c. multiple maceration process
process for concentrated preparations which include both
(Double Maceration ) and ( Triple Maceration )
• Multiple maceration process is carried out in the same way
as simple maceration process , but the menstrum used is
divided into two parts in double maceration process and
into three parts triple maceration process.
• Example for concentrated infusion prepared by double
maceration process: concentrated infusion of orange.
• Example for concentrated infusion are prepared by triple
maceration: Liquid Extract of Senna.

26. 4. Percolation
• Percolation is more efficient than maceration because it is a
continuous process in which the saturated solvent is
constantly being replaced by fresh solvent.
• The various percolation process used for the extraction of
drug are:-
• 4.1. simple percolation or percolation process for
tinctures:
• Apparatus (1) conical percolator
(2) cylindrical percolator
(3) steam jacketed percolator

27. • Method:
• there are three stages:
• i) Imbibition
• The powdered drug is moistened with sufficient quantity of
menstrum and allowed to stand for 4 hours in a closed
vessel.
• ii) Maceration
• the moistened drug is left in contact with menstrum for 24
hours . During this period, the menstrum dissolves the
active constituents of the drug and becomes almost
saturated with it.
• iii) percolation
• It consists of the down ward displacement of the
saturated solution formed in maceration and extraction of
the remaining active constituents present in the drug by the
slow passage of the menstrum through the column of the
drug . Example:- strong tincture of ginger.

28. • 4.2. percolation process for concentrated preparations
• percolation process for concentrated preparations are used
for preparing concentrated preparations are:
• A) reserve percolation process
• B) modified percolation process

29. • A) reserve percolation process
• In this process, generally ¾ th the volume of the finished
preparation, is reserved. Then the percolation process is
continued till the drug is completely exhausted. The
percolate is subjected to evaporation or distillation to
convert it into a soft extract. This soft extract is dissolved
in the reserve portion of percolate and then sufficient
menstrum is added to produce the required volume.

30. • 4.3. Modified percolation process
• The ratio between drug : percolate is reduced by modifying
the percolation process and hence there is a lot of saving in
heat, time and menstrum.

31. Soxhlet extraction (Continuous hot percolation process or
soxhelation)
• The Soxhlet extraction method integrates the advantages
of the reflux extraction and percolation, which utilizes the
principle of reflux and siphoning to continuously extract the
herb with fresh solvent. The Soxhlet extraction is an
automatic continuous extraction method with high
extraction efficiency that requires less time and solvent
consumption than maceration or percolation.
• The high temperature and long extraction time in the
Soxhlet extraction will increase the possibilities of thermal
degradation.

32. 5. Digestion
• The drug is extracted by heating at particular pressure.
This will increase the penetration power of the menstrum,
so that there is complete extraction of the drug.

33. 6. Reflux extraction
• Reflux extraction is more efficient than percolation or
maceration and requires less extraction time and solvent.
• It cannot be used for the extraction of thermolabile
natural products.

34. Modern or Greener
Extraction Methods
1. Pressurized liquid extraction (PLE)
• (PLE) has also been described as accelerated solvent
extraction, enhanced solvent extraction, pressurized fluid
extraction, accelerated fluid extraction, and high pressure
solvent extraction by different research groups.
• PLE applies high pressure in extraction. High pressure keeps
solvents in a liquid state above their boiling point resulting
in a high solubility and high diffusion rate of lipid solutes in
the solvent, and a high penetration of the solvent in the
matrix. PLE dramatically decreased the consumption of
extraction time and solvent and had better repeatability
compared to other methods.

35. 2. Supercritical fluid extraction (SFE)
• (SFE) uses supercritical fluid (SF) as the extraction
solvent. SF has similar solubility to liquid and similar
diffusivity to gas, and can dissolve a wide variety of natural
products. Their solvating properties dramatically changed
near their critical points due to small pressure and
temperature changes.
• Supercritical carbon dioxide (S-CO2) was widely used in
SFE because of its attractive merits such as low critical
temperature (31 °C), selectivity, inertness, low cost, non-
toxicity, and capability to extract thermally labile
compounds.

36. • The low polarity of S-CO2 makes it ideal for the extraction
of non-polar natural products such as lipid and volatile oil.
• A modifier may be added to S-CO2 to enhance its solvating
properties significantly.

37. 3. Ultrasound assisted extraction (UAE)
• Also called ultrasonic extraction or sonication, uses
ultrasonic wave energy in the extraction. Ultrasound in the
solvent producing cavitation accelerates the dissolution and
diffusion of the solute as well as the heat transfer, which
improves the extraction efficiency.
• The other advantage of UAE includes low solvent and
energy consumption, and the reduction of extraction
temperature and time.
• UAE is applicable for the extraction of thermolabile and
unstable compounds. UAE is commonly employed in the
extraction of many types of natural products

38. 4. Microwave assisted extraction (MAE)
• Microwaves generate heat by interacting with polar
compounds such as water and some organic components in
the plant matrix following the ionic conduction and dipole
rotation mechanisms. The transfers of heat and mass are in
the same direction in MAE, which generates a synergistic
effect to accelerate extraction and improve extraction
yield.
• The application of MAE provides many advantages, such as
increasing the extract yield, decreasing the thermal
degradation and selective heating of vegetal material.

39. • MAE is also regraded as a green technology because it
reduces the usage of organic solvent.
• There are two types of MAE methods: solvent-free
extraction (usually for volatile compounds), and solvent
extraction (usually for non-volatile compounds)

40. 5. Pulsed electric field (PEF) extraction
• Pulsed electric field extraction significantly increases the
extraction yield and decreased the extraction time because
it can increase mass transfer during extraction by
destroying membrane structures.
• The effectiveness of PEF treatment depends on several
parameters including field strength, specific energy input,
pulse number and treatment temperature.
• PEF extraction is a non-thermal method and minimizes the
degradation of the thermolabile compounds.

41. 6. Enzyme assisted extraction (EAE)
• The structure of the cell membrane and cell wall, micelles
formed by macromolecules such polysaccharides and
protein, and the coagulation and denaturation of proteins at
high temperatures during extraction are the main barriers
to the extraction of natural products.
• The extraction efficiency will be enhanced by EAE due to
the hydrolytic action of the enzymes on the components of
the cell wall and membrane and the macromolecules inside
the cell which facilitate the release of the natural product.
Cellulose, α-amylase and pectinase are generally employed in
EAE.

42. 7. Hydro distillation (HD) and steam distillation (SD)
Are commonly used methods for the extraction of volatile oil.
• Some natural compounds encounter decomposition in HD and
SD.

43. THANKS