Centrifuge is an equipment in which liquid or solid
particles of varying densities are separated by rotating them in a
horizontal circle inside a tube. Denser particles tend to move along the
length of the tube to a larger radius of rotation, moving the less dense
particles to the other end. The force applied on the rotating particles in a
liquid is described in terms of relative centrifugal force. Different
centrifuges are rated by their RCFs .
Centrifuges are used in various laboratories. Laboratory centrifuges have
varieties of uses in chemistry, biology, and biochemistry laboratories for
separating and isolating solids from liquids in a suspension. The solids can
be anything, from insoluble compounds, biomolecules, cell organelles to
whole cells. These centrifuges differ largely in speed and capacity. A
laboratory centrifuge is driven by a motor, causing the liquid samples to
rotate at higher speed. The laboratory centrifuges come in two different
sizes. The larger ones are known simply as centrifuges while the smaller
centrifuges are known as micro-centrifuges or microfuges.
Types of Laboratory Centrifuges
The two most commonly used types of laboratory centrifuges are preparative
and analytical.
- Preparative Laboratory Centrifuges : The preparative
centrifuges are used to isolate specific particles. They are classified
into two types: density and differential. Density centrifuges are used
to separate two fluids of different densities. The mixture of liquids is
rotated inside a rotating container, the denser fluid is pushed to the
wall of the container while the lighter fluid is forced toward the
center. Differential centrifuges isolate particles from a liquid medium
or separate particles of different masses into separate fractions of the
liquid.
- Analytical Laboratory Centrifuges : These centrifuges are
used to measure the physical properties of particle, such as molecular
weight and sedimentation coefficient.
Types of Centrifuges
Microcentrifuge
Microcentrifuge
is a type of laboratory centrifuge, which is smaller in size compared to the
general centrifuge. It is also called microfuge. Microcentrifuge works on
the principle of sedimentation, where the centripetal acceleration is used
to separate substances of different densities. Due to their small sizes,
microcentrifuges are perfect for school and college uses. These
microcentrifuges are low cost and specifically designed for pupils access to
'cutting-edge' biotechnology work.
Table Top Centrifuge
Table
top or bench top centrifuges are used in small laboratories and research
centers. These centrifuges are small in sizes and can be easily moved from
one place to another. The table top centrifuges are equipped with all the
latest technologies. The bench top centrifuges have fixed rotor, provided
with variable number of tube holders.
Mini Microcentrifuges
Mini
microcentrifuges are space saving centrifuges, which have small diameters.
They are able to fulfill a variety of applications, including
microfiltration, quick spin downs, and low speed separations. Operating a
mini microcentrifuge is extremely simple. Switches are provided to control
the speed of rotor and to release the lid lock. Power switch can be used to
start and stop operation.
Centrifuge Accessories
Centrifuge Tubes
Centrifuge tubes are used for putting samples or specimen in the
centrifuges. Centrifuge tubes are chemically resistant to the solvents used.
They should be able to withstand the maximum centrifugal force and
temperature. Centrifuge tubes are made from glass as well as plastics. Glass
Centrifuge tubes are made from high quality glasses. The glass tubes are
expensive than the plastic Centrifuge tube and they don't perform well at
higher centrifugal forces. Plastic Centrifuge tubes are made from
polystyrene or polypropylene. They are found in both variations, disposable
as well as non-disposable. These tubes are provided with covers to prevent
the samples from spilling.
Micro Centrifuge Sample Pestle
The sample pestles used in micro centrifuges are perfect for resuspending
precipitates or lyophilized products. They can also be used for homogenizing
samples in a microcentrifuge tube. The pestles are made of PTFE mounted on
stainless steel shafts. These pestles may be hand held or mounted in a
motorized chuck.
Double Ended Pestle
The
double ended pestles can be used from both ends for the same purposes as the
simple pestles. These double ended pestles are mounted on a stainless steel
shaft. At both the ends, nylon pestles are attached to the shaft. They may
be hand held or mounted in a motorized chuck.
Microcentrifuge Tube Racks
The microcentrifuge tube racks are ideal for holding microcentrifuge tubes.
These racks are usually made of polypropylene. They are stackable and don't
float in water bath. These microcentrifuge racks have sturdy construction.
The capacity of holding microcentrifuge tubes cover a wide range. They
capacity can be as small as 5 to hundreds of tubes.
