The centrifuge process consists of separating particles from a solution according to their size, shape, density and viscosity. The centrifugal force is a very crucial technique in biochemistry and biotechnology. A laboratory centrifuge is a piece of laboratory equipment, driven by a motor, which spins liquid samples at high speed. Laboratory centrifuges work on basis of the sedimentation principle, where the centripetal acceleration is used to separate substances of greater and lesser density. There are various types of centrifuges, depending on the size, the sample capacity and rotor.
Types of centrifuges
These are just some basic types of centrifuges:
– Small Bench Centrifuges: This type of centrifuge is the ideal to work with small amount of material that rapidly sediment like yeast cells, erythrocytes etc., with a maximum field of approximately 3000-7000g. Regular centrifuges are particularly useful when using DNA, RNA, antibodies, viruses or proteins.
– Large Capacity Refrigerated Centrifuges: These centrifuges have a refrigerated rotor chamber and they can change rotor chambers for varying size, with a maximum capacity of 6500 g. It is useful to collect the substances that sediment rapidly like erythrocytes, yeast cell, nuclei and chloroplast.
– High-Speed Refrigerated Centrifuges: They can generate a speed of about 60000g and are used to collect micro-organism, cellular debris, larger cellular organelles and proteins.
– Ultra Centrifuges: In this group there are two types:
(a) The preparative ultracentrifuge: is the option to separate macromolecules, lipoprotein from plasma and deprotonation of physiological fluids for amino acid analysis. The centrifugal force can reach 600000g.
(b) The analytical ultracentrifuge: operates at 500000g. There are three kinds of optical systems: a light absorption system, the alternative Schlieren system and Rayleigh interferometric system, both of which detect changes in the refractive index of the solution.
Types of rotor
There are several types of rotors, but the most widely used are:
1. Swinging Bucket Rotors: This type of rotor stars off in a vertical position and then swings out to a horizontal position.
2. Fixed Angle Rotors: The fixed angles vary from 14° and 40° to the vertical.
3. Vertical Tube Rotors: They are zero angle fixed and tubes are aligned vertically.
Choosing the centrifuge according to the project
The Floor standing high-speed refrigerated centrifuge used to collect microorganisms and cellular samples. Another option is a tabletop high-speed refrigerated centrifuge when the working space is a must.
The PRP centrifuge. Platelet-Rich-Plasma (PRP) is a centrifuge for blood tests and analysis. The way to obtain this Platelet-rich plasma is by separating platelets from other blood cells and their concentration is increased during the centrifugation process. This is a high-end technology device designed to obtain the right sample.
Another common procedure in a biology laboratory is microhematocrit. Microhematocrit is a very useful procedure for determining the ratio of the volume of packed red blood cells to the volume of whole blood by centrifuging a quantity of blood. Microhematocrit centrifuges are very common when it comes to diagnosing blood loss, polycythemia (an elevation of the erythrocyte count to above-normal levels), anaemia, bone marrow failure, leukaemia, and multiple myeloma. The microhematocrit centrifuge can quickly attain to a speed of 11000rpm or more.
The mini centrifuges are very basic and essential elements inside a lab. They are stapled instruments when it comes to research labs that tend to use small tube volumes.
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