Centrifugation is one kind of separation technique by applying centrifugal force. The particles can be separated from a solution according to their size, density, shape, viscosity of the medium, and rotor speed. The centrifuge device works by using the sedimentation principle, where the centripetal acceleration causes denser substances and particles to move outward in the radial direction.
The radial acceleration causes denser particles to settle to the bottom of the tube, while low-density substances rise to the top when the centrifugation technique applies. The sedimentation of two particles can be found in the presence of centrifugal force rather than gravitational force.
Principle of Centrifugation
The principle of this mechanism relates to the principle of sedimentation. It helps to separate the particles suspended in liquid media under the influence of a centrifugal field. These samples must be placed either in tubes or bottles in a rotor in the centrifuge.
The suspended material settles out of the fluids by gravity. It is possible to separate the particles having sizes less than 5 micrometers. It is possible to sediment the two particles by centrifugal force rather than gravitational force.
Process of centrifugation
The centrifuge machine holds a mixture of solid and liquid or two liquids. This machine can be rotated by applying centrifugal force. Then the container rotates rapidly. The various densities of liquid are separated after rotation properly.
Types of Centrifuge
LOW-SPEED CENTRIFUGE
This type of centrifuge has a standard low speed which is suitable for routine sedimentation of heavy particles. It has a maximum speed of 4000-5000 rpm. This apparatus is used at room temperature with no means of temperature control.
This centrifuge machine is very suitable for the sedimentation of red blood cells until the particles are strongly packed into a pellet and the supernatant is separated by decantation.
HIGH-SPEED CENTRIFUGES
This type of centrifuges is used in more sophisticated biochemical applications, higher speeds and temperature control of the rotor chamber are essential. It has a higher-speed centrifuge force. The maximum speed of this centrifuge is 15,000 – 20,000 RPM. There have three types of rotors for high-speed centrifugation. These are fixed angle, swinging bucket, and vertical rotors.
ULTRACENTRIFUGES
This centrifuge has a maximum speed of 65,000 RPM (100,000’s x g). It is a very sophisticated instrument that can generate heat due to high speed thus the spinning chambers must be refrigerated and kept at a high vacuum. This apparatus can be used for both preparative work and analytical work.
Density gradient centrifugation: This type is suitable for the separation of many or all components in a mixture as well as measurement.
It can be classified into two types: rate zonal centrifugation and isopycnic or sedimentation equilibrium centrifugation
Rate zonal centrifugation: It is found A density gradient of the solution in rate zonal centrifugation. It is possible to segment through the gradient due to centrifugal force. Then the particles begin segmenting into distinct zones based on their size, shape, and density.
Isopycnic or sedimentation equilibrium centrifugation:
This type relates to a wider range of densities of solution. It is possible to separate particles into zones in sedimentation based on their density difference, regardless of time by this technique.
Applications
This method is used to separate two miscible substances. It analyzes the hydrodynamic properties of macromolecules. It is used for the purification of mammalian cells. It can be possible to separate various particles from water. It is used for separating particles from an airflow using cyclonic separation.
It is also suitable for the separation of urine components and blood components in forensic and research laboratories. It can be used for removing fat from milk to produce skimmed milk. It is possible to separate the crystalline drugs from the mother liquor by this technique. It is possible to test the emulsion and suspensions for creaming and sedimentation at an accelerated speed. Biological products can be produced by helping this process. It is possible to determine the molecular weight of collide.
