Different Centrifugation Techniques

Centrifugation is a method of separating substances, which includes the application of centrifugal force. The elements are separated from a solution according to their shape, size, density, the medium's viscosity, and rotor speed. For example, the phosphate treatment centrifuge is used to check the levels of phosphate in the blood. There are different types of centrifugation techniques, including the following.

Differential Pelleting

Differential Pelleting is considered the most common type of centrifugation technique. Tissue, like of liver, is homogenized at 32 degrees in a sucrose solution that contains buffer. The homogenate is then kept in a centrifuge and spun at continual centrifugal force at a constant temperature. After some time, sediment is produced at the bottom of a centrifuge known as the pellet and an overlying solution called supernatant. The overlying solution is then kept in another centrifuge tube, which is then revolved at higher speeds in progressing steps.

Density Gradient Centrifugation

The density gradient centrifugation is mainly used to separate viruses, ribosomes, membranes, etc. A sucrose density gradient is produced by mildly overlaying lesser sucrose concentrations on higher concentrations in centrifuge tubes. The particles of interest are kept on top of the gradient and centrifuge in ultracentrifuges. The particles pass through the gradient until they reach a point at which their density matches the density of surrounding sucrose. The fraction is detached and analyzed.

Rate-Zonal Density-Gradient Centrifugation

Zonal centrifugation is also called a band or gradient centrifugation. It depends on the concept of sedimentation coefficient (i.e., movement of sediment through the fluid medium). In this type, a density gradient is produced in a test tube with sucrose and high density at the bottom. The sample of protein is placed on the top of the gradient and then centrifuged. With centrifugation, faster-sediment particles in sample move ahead of slower ones, i.e., sample separated as zones in the gradient. According to their sedimentation, the coefficient and the fractions of the protein sediment are collected by making a hole at the tube base.