A centrifuge is a device for separating particles from a solution according to their size, shape, density, viscosity of the medium and rotor speed. The process is called centrifugation. In a solution, particles whose density is higher than that of the solvent sink (sediment), and particles that are lighter than it float to the top. The greater the difference in density, the faster they move.

1. Presented by:
MD. MOHABBOT HOSSEN
B.Pharm (Hon’s)
Dhaka International University

2. Introduction
Centrifugation
•Process used to separate
materials suspended in a
liquid medium.
Centrifuge
•It is a device that is used
for Centrifugation

3. Principle
A centrifuge is used to separate particles or macromolecules.
Basis of separation:
Size Shape
Density Viscosity
Rotor speed
Theoretical basis: Effect of gravity

4. SUPERNATANT AND A PELLET
Supernatant is the liquid at the top
Pellet is particles at the bottom

5. Instrumentation
It consist of two components
• An electric motor
• A rotor to hold tubes

7. CLASSIFICATION
1 LOW SPEED CENTRIFUGE Maximum 5 × 103 rpm
3 ULTRA CENTRIFUGE Maximum 105 rpm
2 HIGH SPEED CENTRIFUGE Maximum 2 × 104 rpm
On the basis of speed

8. MODES OF CENTRIFUGATION
Differential
centrifugation
• Rate zonal centrifugation
• Isopycnic centrifugation
Gradient
centrifugation
Ultra
centrifugation

9. DIFFERENTIAL CENTRIFUGATION
Common procedure in microbiology and cytology.
1 First homogenized tissue sample to mix up the cell contents
2 The homogenate is then subjected to repeated centrifugations
3 Each time removing the pellet and increasing the centrifugal force

10. DIFFERENTIAL CENTRIFUGATION
Increase speed

11. Rate zonal centrifugation
Use solution (sucrose) which
have a density gradient.
The sample is applied in a thin
zone at the top of the centrifuge
tube
Use centrifugal force
Particles will begin sedimenting
through the gradient.
Also called velocity gradient centrifugation

12. Rate zonal centrifugation

13. Isopycnic centrifugation
Uniform mixture of sample
allowing with gradient
forming substances (CsCl)
Use centrifugal force
Gradient is formed
Particle is separated.
Uniform mixture
of sample and
gradient forming
substances
centrifugation
Gradient is formed
and samples band
at their isopycnic
position
Uniform mixture of
sample and gradient
forming substances
centrifugation
Gradient is formed and
samples band at their
isopycnic position

14. APPLICATION
1. Separate two immiscible liquids
2. Isolate cellular organelles
3. Isolate DNA, RNA, and proteins
4. Isolate small particles including:
• Bacteria
• Viruses
• Cells