The key to centrifuge separation is that it uses centrifugal force to separate the components in the mixture according to their physical properties (such as density, size, shape, etc.). The following is the detailed process of centrifuge separation:
Generation of centrifugal force
Principle:
When an object moves in a circular motion around a fixed point (such as the axis of a centrifuge), a force away from the fixed point is generated, namely the centrifugal force. The magnitude of the centrifugal force is proportional to the mass of the object, the radius of rotation, and the square of the angular velocity.
Application:
In a centrifuge, the mixture is placed in a special container (such as a centrifuge tube or rotor). As the centrifuge rotates at high speed, components of different masses or densities begin to separate due to different centrifugal forces.
Sample loading and distribution
The mixture samples to be separated are evenly placed in the sample holes or centrifugal disks of the centrifuge rotor to ensure uniform centrifugal force during rotation.
Rotation and separation
After the centrifuge is started, the motor drives the rotor or centrifugal disk to rotate at high speed, generating a strong centrifugal force. Under the action of centrifugal force, different components in the mixture begin to separate due to differences in their physical properties. Usually, heavier components (such as solid particles, high-density substances) are subject to greater centrifugal force and are pushed to the bottom of the centrifuge tube or centrifugal disk; while lighter components (such as liquids, low-density substances) are located in the upper layer or form an intermediate layer.
Collection and processing of separation results
After the centrifugation process is completed, the centrifugal rotor or centrifugal disk stops rotating.
Different methods are used to collect the separated components as needed. For example, lighter components can be collected by pouring the upper liquid, and heavier solid particles can be collected by removing the sediment at the bottom of the centrifuge tube, etc.
Examples of centrifugation methods
In addition to the basic centrifugation process, the centrifuge can also use different centrifugation methods to improve the separation effect, such as:
Differential centrifugation:
Separate structures of different densities in the sample, such as mitochondria, chloroplasts, proteins, etc. by gradually increasing the centrifugation speed.
Density gradient centrifugation:
Add the sample to the pre-added gradient medium in the centrifuge tube for speed sedimentation or sedimentation equilibrium to form a separation method with different zones.
Analytical ultracentrifugation:
Mainly used to study the sedimentation characteristics and structure of biological macromolecules, and continuously monitor the sedimentation process of substances in the centrifugal field through special rotors and detection methods.
The centrifuge separates different components in a mixture through four steps: generating centrifugal force, loading and evenly distributing samples, rotating and separating, and collecting and processing the separation results. This process has wide application value in many fields such as biomedical research, chemical analysis, pharmaceuticals, and food industry.