Electrophoresis definition, principle, instrumentation,working, types, advantages, disadvantages and applications with full detailed explanation.

1. By,
Gokul Prasath. A
B.Pharmacy
KMCH COP
Modern Methods of Pharmaceutical Analysis
Seminar
On topic of
1

2. ELECTROPHORESIS
Electrophoresis is a physical analysis which involves
the separation of the compounds that are capable of
acquiring electric charge in conducting electrodes.
2
Greek word meaning “transport by electricity”
(Electro – electricity, phoresis – movement)

3. DEFINITION
• Electrophoresis may be defined as the migration of
the charged particle through a solution under the
influence of an external electrical field.
• Ions that are suspended
between the two electrodes
tends to travel towards the
electrodes that bears
opposite charge.
3

4. PRINCIPLE
Any charged ion or molecule migrates when placed in an
electric field, the rate of migration depend upon its net
charge, size, shape and the applied electric current.
v=Eq/F
Where,
v = velocity of the molecule
E = electric field (Volt/cm)
q = net charge on molecule
F = frictional coefficient, which depends upon mass and
shape of the molecule.
4

5. The rate of migration of an ion in an electrical field
depends on,
1) Net charge of molecule
2) Size, mass and shape of the particle
3) Strength of electrical field
4) Properties of supporting medium
5) Temperature of operation
5

6. FACTORS AFFECTING ELECTROPHORESIS
1) SAMPLE
a) Charge: rate of migration increases with increases in net charge
b) Size: rate of migration decreases for larger molecules. It is due to
frictional and electrostatic forces.
c) Shape: molecules have similar charge but differ in shape exhibit
different migration rate
2) ELECTRIC FIELD
a) Voltage: increase in voltage leads to increase in rate of migration
b) Current: increase in current leads to increase in voltage,
migration also increases
c) Resistance: resistance increases and migration decreases.
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7. 3) BUFFER
a) Ionic strength: rate of migration increases in high ionic
strength
b) pH: ionization of organic acid increases as pH increases
4) SUPPORTING MEDIUM
a) Adsorption: reduces both rate of migration and resolution
of separation of molecule
b) Electro-endosmosis: it is due to the presence of charged
groups on the surface of the supporting medium.
Ex: paper(carboxyl group), agarose (sulphate group) .
It will accelerate the movement of cations, but retard the anion
movements.
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8. TYPES OF ELECTROPHORESIS
a) ZONE ELECTROPHORESIS:
1) Paper electrophoresis
2) Gel electrophoresis
3) Thin layer electrophoresis
4) Cellulose acetate electrophoresis
b) MOVING BOUNDARY/FRONTAL ELECTROPHORESIS:
1) Capillary electrophoresis
2) Isotachophoresis
3) Isoelectric focussing
4) Immuno-electrophoresis
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9. INSTRUMENTATION
(General Apparatus)
It consists basically of items,
1) Power pack
2) Electrophoresis unit
• Electrodes
• Buffer reservoir
• Support for electrolysis
medium
• A transparent insulating
cover
3) Sample injector
4) Detector
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10. GENERAL METHOD OF OPERATION
Saturation of the
medium with the buffer
↓
Sample application
↓
Electrophoretic
separation
↓
Detection
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11. a) ZONE ELECTROPHORESIS
• It involves the migration of the charged particle on the
supporting media.
• Paper, cellulose acetate membrane, starch gel,
polyacrylamide are used.
• Components separated are distributed into discrete zone
on the support media.
• Supporting media is saturated with buffer solution,
small volume of the sample is applied as narrow
band.
• On application of PD at the ends of a strip components
migrates at a rate determined by its electrophoretic
mobility.
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12. ADVANTAGES:
1) Useful in biochemical investigations.
2) Cost is low
3) Small quantity of sample can be analysed.
4) Easy maintenance
DISADVANTAGES:
1) Unsuitable for accurate mobility and isoelectric point
determination.
2) Due to the presence of supporting medium, technical
complications such as capillary flow, electro osmosis,
adsorption and molecular sieving are introduced.
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13. 1) PAPER ELECTROPHORESIS
It is the form of electrophoresis that is carried out on filter
paper. This technique is useful for separation of small
charged molecules such as amino acids and small
proteins.
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14. FILTER PAPER
It is the stabilising medium. Whatman filter paper, cellulose
acetate filter paper or chromatographic papers can be
used.
APPARATUS
Power back, electrophoretic cell that contains electrodes, buffer
reservoirs, support for paper, transparent insulating cover.
SAMPLE APPLICATION
The sample may be applied as a spot (about 0.5 cm in diameter)
or as a uniform streak.
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15. ELECTROPHORETIC RUN
The current is switched on after the sample has been applied to
the paper and the paper has been equilibrated with the buffer.
The types of buffer used depends upon the type of separation.
Once removed, the paper is dried in vacuum oven.
DETECTION AND QUANTITATIVE ASSAY
To identify unknown components in the resolved mixture the
electrophoretogram may be compared with another
electrophoretogram on which standard components have been
electrophoresced under identical conditions.
Physical properties like fluorescence, UV absorption or
radioactivity are exploited for detection.
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16. WORKING
1) In this sample is applied as a
circular support on a strip of
whatman filter paper moistened
with the buffer solution.
2) The ends of the paper are
immersed in separate
reservoirs containing buffer and
in which the electrodes are fitted.
3) Upon passing electric current, the
ions in the sample migrate towards
oppositely charged electrodes.
4) This method is suitable for low
molecular weight compounds
such as amino acids and
nucleotides.
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17. 2) GEL ELECTROPHORESIS
It is a technique used for the separation of DNA, RNA or protein
molecules according to their size and electrical charge using an
electric current applied to a gel matrix.
GEL: Gel is a cross linked polymer whose composition and porosity
is chosen based on the specific weight and porosity of the target
molecules.
TYPES OF GEL
1) Agarose gel
2) Polyacrylamide gel
3) Sephadex gel
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18. AGAROSE GEL ELECTROPHORESIS
• A highly purified uncharged polysaccharide derived form agar.
• Used to separate macromolecules such as nucleic acid, larger
proteins and protein complexes.
• It is prepared by dissolving 0.5% agarose in boiling water and
allowing it to cool to 40°C.
• It is fragile because of the formation of weak hydrogen bonds
and hydrophobic bonds.
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20. SDS PAGE ELECTROPHORESIS
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• Sodium Dodecyl Sulphate Poly-Acrylamide Gel Electrophoresis
• SDS is an anionic detergent which binds strongly to and denature
proteins.
• Protein SDS complex carries net negative charges, hence move
towards anode and the separation is based on the size of the particle
and also be used for determining the relative molecular mass of a
protein.
APPLICATIONS:
1) Useful for protein purification.
2) Determine molecular weight of proteins.
3) Quantifying proteins
4) Blotting applications

21. PROCESS OF SDS PAGE
1) Boil the samples for 10
minutes to completely
denatures the proteins.
2) Assembly the gel into the
apparatus.
3) Pour the buffer solution into
the chamber.
4) Load 20µL of samples into the
well.
5) After that, run electrophoresis
by connecting the current
supplies.
6) Visualises the band under UV
light or staining technique.
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22. 3) THIN LAYER ELECTROPHORESIS
Electrophoretic studies can be carried out in thin layer of silica,
keisulghur, alumina.
ADVANTAGES:
1) Less time consuming
2) Good resolution
APPLICATION:
Used in combined electrophoretic-chromatography studies in
two dimensional study of proteins and nucleic acid
hydrolysates.
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23. 4) CELLULOSE ACETATE ELECTROPHORESIS
• It contains 2-3 acetyl groups per glucose unit and its adsorption
capacity is less than that of paper.
• It gives sharper bands.
• Provides a good background for staining glycoproteins.
ADVANTAGES:
1) No tailing of proteins
2) Gives sharp bands and good resolution.
DISADVANTAGES:
1) Expensive
2) Presence of carboxylic residue causes induced electro-osmosis
during process.
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24. PRINCIPLE
• In an alkaline pH (8.2-8.6)
Haemoglobin is a
negatively charged(-)
molecule and will migrate
toward the anode(+).
• The various Haemoglobin
moves at different rates
depending on their net (-)
charge, which in turn is
controlled by the
composition of the
Haemoglobin molecule.
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25. b) MOVING BOUNDARY ELECTROPHORESIS
PRINCIPLE:
The moving boundary method allows the charged species to migrate in a
free moving solution without the supporting medium.
ADVANTAGES:
1) Biologically active fractions can be recovered without the use of
denaturing agents.
2) Minute concentrations of the sample can be detected.
DISADVANTAGES:
1) Costlier
2) Elaborate optical system are required.
APPLICATIONS:
1) To study homogenecity of a macromolecular system.
2) Analysis of complex biological mixture.
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26. INSTRUMENTATION
• Consists of a U shaped glass
cell of rectangular cross
section with electrodes placed
on the one each of the limbs of
the cell.
• Sample solution is introduced
at the bottom or through the
side arm and the apparatus is
placed in a constant temp.
bath at 40°C.
• Detection is done by
measuring refractive index
throughout the solution
(Schileren optical system).
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27. 1) CAPILLARY ELECTROPHORESIS
• Capillary tube is placed between the two buffer reservoir and
an electric field is applied, separation depends on
electrophoretic mobility and electro-osmosis.
• Defined volume of analyte is introduced into the capillary by
replacing one buffer reservoir with sample vial.
• Electrophoretic separation is measured by detector.
• Using narrow bore tubes, capillary electrophoresis removes
the joule heating effect which decreases band broadening,
giving faster separations than gel.
• CE uses tubes 20-100µm diameter and 20-100cm
length.
• CE is used with/without gel.
• Longitudinal diffusion is the main source of band-broadening.
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28. • Higher electric fields result
in high efficiency and
narrow peaks (analyte
migrates faster).
• All analytes travel the same
distance, but the
migration time (tm) for
that distance is measured.
• Relate time to identity.
• Relate peak area or height
to amount.
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29. 2) ISOTACHOPHORESIS
• Iso – equal, tachos – speed, phoresis – migration
• The technique of isotachophoresis depends on the
development of potential gradient.
• Used for separation of smaller ionic substances.
• They migrate adjacent with contact one another, but not
overlapping.
• The sample is not mixed with buffer prior to run.
• Hence current flow is carried entirely by the sample ions.
APPLICATION:
Separation of small anions and cations.
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30. 3) ISO ELECTRIC FOCUSSING
• Isoelectric focussing also known as electro-focussing is a
technique for separating different molecules by differences in
their isoelectric point.
• It is suitable for separation of amphoteric substances.
• It is a type usually performed on proteins in a gel, that takes
advantages of the fact that overall charge on the molecule of
interest is a function of the pH of its surroundings.
• Method has high resolution.
APPLICATIONS:
1) Human genetic lab.
2) Useful for separating iso-enzymes.
3) Research in enzymology and immunology.
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31. 4) IMMUNO ELECTROPHORESIS
• When electrical field is applied to study of antigen-
antibody reactions, it is called immuno-electrophoresis.
• The antibody are electrophoretically separated and antigens
diffuse towards each other resulting in precipitin arcs
where antigen antibody complexes form.
• It is used to detect the presence of antibodies.
• Used mainly to determine the blood levels of three major
immunoglobulins :
IgM
IgG
IgA
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32. PROCESS
• Ag molecules are separated according to differences in their
electrical charge by electrophoresis.
• Antibody is placed in a trough cut in the agar.
• Antibody diffuse towards antigen → precipitin arcs.
• Interpretation – precipitin arc represent individual
antigens.
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33. APPLICATIONS OF ELECTROPHORESIS
1) DNA sequencing
2) Medical research
3) Protein research/purification
4) Agricultural testing
5) Separation of organic acid, alkaloids, carbohydrates, amino
acids, alcohols, phenols, nucleic acids, insulin.
6) In food industry
7) It is employed in biochemical and clinical fields ie., in the
study of protein mixtures such as blood serum, haemoglobin
and in the study of antigen-antibody interactions.
8) Electrophoresis in combination with auto-radiograhy is used
to study the binding of iron to serum proteins.
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34. 9) Used for analysis of terpenoids, steroids and antibiotics.
10) For testing purity of thyroid hormones by zone
electrophoresis.
11) Paper chromato-electrophoresis is used to separate free
insulin form plasma proteins.
12) It is used for diagnosis of various disease of kidney, liver and
CVS.
13) It is also used for separation of scopolamine and ephedrine
using buffer at pH 4.2
14) It is also used for separation of carbohydrates and vitamins.
15) Quantitative separation of all fractions of cellular entities,
antibiotics, RBC, enzymes, etc.., are possible.
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