CENTRIFUGE

 Centrifugation is a term used to describe a method of separating mixtures using spinning and centrifugal force. Several characteristics can separate particles during centrifugation, including size, shape, density, and viscosity.

British military engineer Benjamin Robins, who built a device that resembled an arm rotating around an axis to gauge drag on items. The Prandtl brothers later made the first practical centrifuge to separate milk from the cream by improving this design. By rapidly rotating a container containing material, separation is accomplished, the centrifugal force forces heavier elements to the outside of the container.

Principles of Centrifuge:

The centrifuge utilizes the sedimentation principle due to gravitational force. The centrifugation technique uses a centrifugal field to separate particles suspended in a liquid medium. These are put in the centrifuge’s rotor either in bottles or tubes. Sedimentation is a process in which gravity causes suspended particles to separate from a fluid. The suspended substance may consist of powder or clay-like particles.

1. Motor: The motor is the powerful central component of the centrifuge that creates the spin.
2. Rotor assembly: A drive shaft and a rotor comprise the rotor assembly. The drive shaft provides support for the rotor components.

 Fixed-angle rotors: These rotors hold the tubes at an angle of 14 to 40° to the vertical, such that particles travel a short distance while moving radially outwards and are used in differential centrifugation.

 Swinging bucket/ Horizontal rotors: These rotors, along with the centrifuge tubes, swing out to a horizontal position during the time of acceleration such that particles travel a longer distance, thereby facilitating easier separation of supernatant from the pellet. 

Vertical rotors: These hold the tubes vertically, i.e., parallel to the motor axis, and the particles move shorter distances with shorter periods for separation.

 

3. Containers: Several types of containers, such as test tubes, blood bags, cuvettes, centrifuge tubes, etc., are held in the rotors such that the sample rotates along as the rotor rotates.
4. Control Panel: It serves the purpose of controlling different parameters such as temperature, rotational speed (rcf or rpm), etc.
5. Latch: When a tube breaks or there are other issues with the centrifuge while running, the latch keeps the lid closed.
6. Lid: The centrifuge will only spin if the lid is closed and locked to prevent mishaps.

Types of centrifugation techniques:

• Differential centrifuge.
• Density gradient centrifuge.
• Analytical centrifuge.

Types of centrifuges:

• Benchtop or tabletop centrifuge.
• Gas centrifuge.
• Microcentrifuge.
• Refrigerated centrifuge.
• High-speed centrifuge.
• low-speed centrifuge.
• ultra centrifuge.
• Continuous flow centrifuge.

Procedure:

• Check the instrument for any restrictions and proper operation.
• Check the centrifuge tubes before running in instrument.
• Fill the liquids in the tubes.
• Balance the tubes at an equal ratio of liquid in both tubes.
• Screw the tube and ensure it is tight.
• keep the tubes in the centrifuge.
• While running the machine at max speed, check for vibrations or unusual sounds.
• Turn off the centrifuge in the cluster and wait for the rotation to stop before extracting the sample from the centrifuge.

Applications:

• Chemistry.
• Clinical labs.
• Dairy industry.
• Nuclear plants.
• Petroleum.

Advantages:

• Easy to handle.
• High flexible.
• Low cost.
• Automation.

Limitations:

• High energy usage.
• Maintenance.
• Noise pollution.
• Service cost.