Centrifugation

From Wikipedia, the free encyclopedia

Centrifugation is a process that involves the use of the centripetal force for the separation of mixtures, used in science labs. In chemistry and biology, increasing the effective gravitational force on a test tube so as to more rapidly and completely cause the precipitate ("pellet") to gather on the bottom of the tube. The solution ("supernatant") is then either quickly decanted from the tube without disturbing the precipitate or withdrawn by means of a medicine dropper. The rate of centrifugation is specified by the acceleration applied to the sample, typically measured in revolutions per minute (RPM) or g. The particle’s settling velocity in centrifugation is a function of the particle’s size and shape, centrifugal acceleration, the volume fraction of solids present, the density difference between the particle and the liquid, and the viscosity.

[edit] Types

There are various types of centrifugation:

• Differential centrifugation
• Isopycnic centrifugation
• Sucrose gradient centrifugation

[edit] Other applications

• Separating textile.
• Removing water from lettuce after washing it.
• Separating particles from an air-flow using cyclonic separation.

[edit] See also

• Centrifuge