The document discusses centrifuges and centrifugation. It begins by summarizing the early history of centrifuges, including inventions in the 18th and 19th centuries. It then provides definitions and explanations of key terms like centrifuge, centrifugation, and relative centrifugal force. The rest of the document details different types of centrifuges, components of centrifuges, separation techniques, and rotors and tubes used in centrifugation.

3. English military engineer Benjamin Robins
(1707-1751) invented a whirling arm apparatus
to determine drag.
In 1864, Antonin Prandl invented the first dairy
centrifuge in order to separate cream from milk.
In 1879, Gustaf de Laval demonstrated the first
continuous centrifugal separator, making its
commercial application feasible.

4. WHAT IS CENTRIFUGE?
Centrifuge is device for separating particles from a
solution according to there size, shape, density,
viscosity of the medium.
WHAT IS CENTRIFUGATION?
Centrifuge uses centrifugal force to separate
phases of different densities.

5. Centrifugation is a procedure that involves the use of centrifugal
force for the sedimentation of mixture with a centrifuge used in
industry and in laboratory settings. More dense components of the
mixture move away from the axis of the centrifuge while less
dense components of the mixture move towards the axis.

6. A particle whether it is a precipitate a macromolecule or a cell organelle is
subjected to a centrifugal force when it is rotated at a high rate of speed. The
centrifugal force F is denoted by equation
F=mω2 r
Where
F= intensity of the centrifugal force
m= effective mass of the sedimenting particle
ω= angular velocity of rotation
r= distance of the migrating particles from the central axis of
rotation
A more common measurement of F in terms of the earths gravitation force , g,
is relative centrifugal force, RCF its defined by
RCF = 1.119 x 10-5 (rpm)2 (r)
This equation relates RCF to revolutions per minute of the sample . Equation
dictates that the RCF on a sample will vary with r, the distance of the
sedimenting particles from the axis of rotation . The RCF value is reported as “ a
number times gravity ,g .”

7. A centrifuge is a piece of equipment, generally driven by an electric motor, that
puts an object in rotation around a fixed axis, applying a force perpendicular to
the axis to separate substances of different densities.
Tubes in the centrifuge are tilted so centrifugal force can pull denser substances
towards the bottom of the tube.
Relative Centrifugal Force (RCF) measures acceleration applied to the sample
RCF=(r*ω2)/g
r=distance from center or motor to sample
ω= angular velocity (radians/ second)
g=9.8m/s2

8. Feed added to spinning bowl
Sedimentation of particles occurs
in centrifugal field
Flow is upwards at a particular rate
which determines residence time
in device
Separation happens if
sedimentation velocity is high
enough for particle to reach side of
bowl within residence time
Large particles have higher settling
velocities than small particles
Both large and small are still
particles, have small Reynolds no.s
(<1) and obey Stokes’ Law

9. On and off control, operation time control (timer),
rotation speed control, temperature control (in
refrigerated centrifuges), vibration control (safety
mechanism) and brake system
Refrigeration system (in refrigerated centrifuges).
Base
Lid/cover
Casing
Electric motor
Rotor.
There are different types of rotors. The most common are
the fixed angle, the swinging buckets, the vertical tube
and the almost vertical tube types.

11. The basic centrifuge consists of two components one is Electric
motor with drive shaft to spin the sample and a Rotor to hold tubes
or other containers of the sample. A wide variety of centrifuges are
available ranging from a low speed centrifuge used for routine
pelleting of relatively heavy particles. There are three types of
centrifuges
1. Low –speed centrifuges .
Its also called as clinical centrifuge.
The common centrifuge has a maximum speed in the range of
4000 to 5000 rpm with RCF value approx. up to 3000Xg. These
instruments usually operate at low temperature with no means
of temperature control of the samples.
Two types of rotors fixed angle and swinging bucket may be
used in this instruments.

13. Low speed centrifuges are especially useful for the rapid sedimentation of
coarse precipitates or red blood cells.
The sample is centrifuged until the particles are packed into a pellet at the
bottom of the tube. The upper liquid portion, the supernatant, is then
separated by decantation.
2. High Speed Centrifuges:
High speed centrifuges for more sophisticated biochemical applications.
Higher speeds and temperature control of the rotor chambers are essential.
Rotor chambers in most instruments are maintained at or near 40 C. Three
types of rotors are available for high speed centrifugation.
a. Fixed Angel rotor.
b. Swinging –bucket rotors
c. vertical rotor
High speed centrifuges are used to sediment
a. Cell debris after cell homogenization.
b. Ammonium sulfate precipitates of proteins and cellular organelles such
as chloroplasts, mitochondria and nuclei.

15. 3. Ultracentrifuges:
The most sophisticated of the centrifuges are the
ultracentrifuges because of the high speeds attainable intense
heat is generated in the rotor so the spin chamber must be
refrigerated and placed under high vacuum to reduce friction.
it is a high speed centrifuge that has fixed head rotors .It is
mainly used in separation of lipoproteins .since the separation
is long process there is generation of heat and thus are provided
with internal cooling system.
Ultracentrifuges can be used both for preparative work as well
as for analytical. Preparative models its primarily used for
separations and purification of samples for further analysis and
analytical models which are designed for performing physical
measurements on the sample during sedimentation.

17. a) Preparative
1. Differential Centrifugation
2. Density gradient Centrifugation
2a. Rate-Zonal
2b. Isopycnic
b) Analytical

18. It is used to separate organelles and molecules
It can handle larger liquid volumes
no optical read-out
Separation methods used in preparative
ultracentrifugation:
1. Differential Centrifugation- pelleting,
2. Density Gradient Centrifugation

19. based on the size of the particles
used for simple pelleting, for the separation of
subcellular organelles and macromolecules
first, sample must be homogenised
ultra centrifugation
sedimentation depends on mass, shape and
partial specific volume of a macromolecule, as
well as solvent density, rotor size, rate of
rotation.
Usually uses a fixed angle rotor

21. method to purify subcellular organelles and
macromolecules.
density gradients generated by placing layer
after layer of gradient media
Density gradient centrifugation classified into
two:
2a. Rate-Zonal separation (size)
2b. Isopycnic Separation (Density)

23. use of continuous density gradient of solvent
such as sucrose.
density increases towards the bottom of the
tube
sample layered on the top
molecules form discrete bands after
centrifugation
separation based on size of the molecules
Swinging bucket rotors

25. based on the density of the molecules
Mix gradient material with the sample molecule (CsCl)
molecules move to the position where their density is
same as the gradient material (isopycnic position)
inorder to generate a gradient, we select a CsCl
concentration that will give a range of densities that
includes the range of molecules that have to be
separated.
used for the separation of DNA
Swinging bucket or fixed angle rotor

27. uses small size samples
built-in optical system
uses relatively pure sample

28. Types centrifuges depends upon
Maximum speed of sedimentation
Presence /absence of vacuum
Temperature control refrigeration.
Volume of sample and capacity of
centrifugation tubes
Depending on the particular application,
centrifuges differ in their overall design and size.
a common feature in all centrifuges is the
central motor that spins a rotor containing the
samples to be separated

30. With or without refrigeration
Slow speed (eg up to 4000 RPM)
Common in clinical lab (blood/plasma/serum
separation)
can take approx (up to) 100 tubes, depending
on diameter

32. (“microfuge”, “eppendorf”)
Sample volume is small in tubes
Refrigerated with or without
can generate forces up to ~15,000 x g
Take tube of small volume up to 2ml.
Commonly used of concentration protein
very common in biochemistry/molecular
biology/biological labs

34. (15,000–20,000RPM)
Refrigerated
use for protein precipitates, large intact
organelles cellular debris from tissue
homogenisation and micoorganism
They operate maximal centrifugal force of
approx 10000g
Use for research applications
differntial sepration of nucleus, mitrochondrial,
protein precipitate,etc.

36. (65,000RPM)
Refrigerated and evacuated
The detail biochmestry analysis of subcellular
structures and isolate biomolecules.
Operate at upto 90000 g
limited lifetime
expensive
require special rotors
care in use – balance critical!
research applications

38. Centrifugal fields of 3000 to 7000g.
Efficient separation of coarse precipitates or whole
cells.

39. Fixed angle
Swinging bucket rotors (Vertical/ Horizontal)

40. The rotor (mainly made of aluminium) is very compact.
There are boreholes with a specific angle (like 45°) within the
rotor.
These boreholes are used for the sample tubes.

41. a. Vertical rotors
Vertical rotors Sample tubes are held in vertical position during rotation
This type of rotor is not suitable for pelleting applications but is most
efficient for isopycnic (density) separations due to the short pathlength .
Applications include plasmid DNA, RNA, and lipoprotein isolations.
b. horizontal rotors
The rotor looks like a cross with bucket.
Within these buckets, different tubes can be centrifuged.
For a safe centrifugation, a specific adadpter for every tube shape is
mandatory.

42. Centrifuge tubes or centrifuge tips are tapered tubes
of various sizes made of glass or plastic.
They may vary in capacity from tens of mm, to much
smaller capacities used in micro-centrifuges used
extensively in molecular biology laboratories.
The most commonly encountered tubes are of about
the size and shape of a normal test tube (~ 10 cm
long).
Micro-centrifuges typically accommodate micro-
centrifuge tubes with capacities from 250 μl to 2.0 ml
These are exclusively made of plastic.

43. Glass centrifuge tubes can be used with most solvents,
but tend to be more expensive. They can be cleaned
like other laboratory glassware, and can be sterilized
by autoclaving.
Plastic centrifuge tubes, especially micro-centrifuge
tubes tend to be less expensive. Water is preferred
when plastic centrifuge tubes are used. They are more
difficult to clean thoroughly, and are usually
inexpensive enough to be considered disposable

44. Three microcentrifuge tubes: 2 mL, 1.5 mL and 200 μL (for
PCR).
Four screw-top micro-centrifuge tubes Four screw-top
micro-centrifuge tubes.

45. Centrifugal field from the center of rotation may be
calculated using the equation
G=ω2 r
Angular velocity ω may be calculated by using
this equation
ω= 2 π rev min-1
60

46. Separate solids from solution
Used during urinalysis to separate disease identifying components
Separate blood into plasma Purification of mammalian cells
Fractionation of subcellular organelles (including membranes / membrane
fractions)
Fractionation of membrane vesicles

48. • Centrifuges with a batch weight of up to 2,200 kg
per charge are used in the sugar industry to
separate the sugar crystals from the mother liquor.
• Standalone centrifuges for drying (hand-washed)
clothes – usually with a water outlet.
• Large industrial centrifuges are also used in the oil
industry to remove solids from the drilling fluid.

49. Lubricate and clean motor.
Clean case.
Inspect power cords and plugs.
Inspect controls and switches.
Ensure appropriate menu settings for proper use.
Ensure tightness of rotor.
Check lights and indicators.
Verify that alarms are operating properly.
Ensure safety switch is functioning.
If refrigerated, ensure temperature reading is working.
Replace/repair gaskets, seals, and vacuum pump (if
applicable).

50. Machine will not start.
Power supply is faulty.
Safety switch or timer not working properly.
Motor not working properly.
Motor making noise.
Rotor is broken.
Lid will not open or close.