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Centrifuge Basics for Biotech Students

The document describes an experiment using centrifugation to separate particles from a solution. It explains that a centrifuge uses centrifugal force to separate components of a mixture based on properties like size, shape, and density. Components that are denser move outward while less dense components move inward. The document discusses different types of rotors and tubes used in centrifuges, and how the centrifuge speed and radius determine the relative centrifugal force and time required for separation.

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Arnab Roy
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342 views2 pages

Centrifuge Basics for Biotech Students

The document describes an experiment using centrifugation to separate particles from a solution. It explains that a centrifuge uses centrifugal force to separate components of a mixture based on properties like size, shape, and density. Components that are denser move outward while less dense components move inward. The document discusses different types of rotors and tubes used in centrifuges, and how the centrifuge speed and radius determine the relative centrifugal force and time required for separation.

Uploaded by

Arnab Roy
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as DOCX, PDF, TXT or read online on Scribd
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Experiment No.

Aim
Application of centrifugal force to separate particles from solution.

Apparatus
Refrigerated centrifuge (Kubota 6930), 2 plastic tubes, distilled water, sample, etc.

Theory
A centrifuge is a device for separating particles from a solution using centrifugation
technique. Centrifugation is a mechanical process that utilizes an applied centrifugal force
to separate the components of a mixture according to their size, shape, density, viscosity of
the medium and rotor speed. The centrifuge works on the principle of increasing effective
gravity to enhance the ratio of settling of suspended particles denser than buffer.
The centrifugal acceleration causes denser substances and particles to move outward in the
radial direction. At the same time the objects that are less dense get displaced and move
towards the centre. This technique plays crucial role in biochemistry or biotechnology.
The principle component of a centrifuge is the rotor, which is the moving part that spins at
high speeds. It is mainly of two types fixed angle and swinging bucket type rotor. In fixed
angle rotor sedimenting particles have only shorter distance to travel before pelleting which
helps in reducing time for separation. Swinging bucket rotor gives better separation as the
length to be travel by particle is more and both supernatant and sediment is easy to separate.
In centrifuge there are mostly plastic and glass tube used for separation. Glass tube can be
used with most solvents and can be sterilized by autoclave while plastic tubes are preferred
when water as solvent is used.
In centrifugation, relative centrifugal force (RCF) is the force required to separate two
phases, this force also called relative centrifugal field. Units are expressed as number of times
greater than gravity. By accelerating the g speedy sedimentation can be achieved. RCF is
calculated as follows:
RCF = 1.118 X 10-3 x N2 x R
Where 1.18 x 10-3 are an empirical factor
N= speed of rotation of rotor in revolutions per minute.
R= radius in m from the center of rotation to the bottom of the tube in rotor cavity or bucket
during centrifugation
Time required to sediment particles depends on the rotor speed, radius of the rotor, and
effective path length travelled by sedimented particles i.e. the depth of liquid in the tube.
Types of centrifuge depends of speed of sedimentation, presence or absence of vacuum,
temperature control refrigeration and volume of sample and capacity of centrifugation
tubes. According to the requirement and application type of centrifuge is chosen.

Observations

Calculations

Results

Inference/Conclusion

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