Centrifugation
Centrifugation separates particles or phases by spinning them, using centrifugal effects and differences in sedimentation behavior.
Sedimentation coefficient: A measure of how quickly a particle sediments under applied acceleration, expressed in Svedberg units. It captures the combined effects of particle size, shape, and density on migration during centrifugation.
Cell fractionation: The separation of cellular components into distinct fractions for analysis or use. Sequential centrifugation can isolate nuclei, organelles, membranes, and soluble contents.
Sedimentation: The settling or movement of suspended material through a fluid under an applied force. Centrifugation accelerates sedimentation to make separation faster or possible for small particles.
Filtration: A separation method that passes a mixture through a porous barrier to retain selected components. Unlike centrifugation, filtration separates by access through pores rather than sedimentation behavior.
Relative centrifugal force: The acceleration produced by rotation, expressed as a multiple of Earth's gravitational acceleration. It translates rotor speed and radius into the acceleration acting on suspended particles.
Blood plasma: The liquid component of blood that remains after blood cells are removed. Spinning anticoagulated blood separates plasma from cellular components.
Suspension: A mixture in which solid particles are dispersed through a fluid without dissolving. Many centrifugation samples begin as suspensions whose particles migrate at different rates.
Electrophoresis: The movement of charged particles through a medium under an electric field. It separates many biomolecules by electrically driven mobility rather than centrifugal sedimentation.
Stokes' law: A relation describing the drag force on a small sphere moving slowly through a viscous fluid. Its assumptions help explain how particle size, density contrast, and viscosity affect sedimentation.
Apheresis: A medical procedure that removes selected blood components and returns the remainder to the body. Centrifugal cell separators distinguish blood components for collection or treatment.