| | | | | the liquid, and the viscosity. |
| | | | | In microcentrifugation, centrifuges are run in batch |
| Centrifugation is a process that makes use of the | | | | to isolate small volumes of biological molecules or |
| centrifugal force for the separation of mixtures, | | | | cells (prokaryotic and eukaryotic). Nuclei is also |
| used in industry and in medical laboratory settings. | | | | often purified via microcentrifugation. |
| More-dense components of the mixture migrate | | | | Microcentrifuge tubes generally hold 1.5-2 mL of |
| away from the axis of the centrifuge, while | | | | liquid, and are spun at maximum angular speeds |
| less-dense components of the mixture migrate | | | | of 12000-13000 rpm. Microcentrifuges are small |
| towards the axis. Chemists and biologists may | | | | and have rotors that can quickly change speeds. |
| increase the effective gravitational force on a | | | | Superspeed centrifuges work similarly to |
| test tube so as to more rapidly and completely | | | | microcentrifuges, but are conducted via larger |
| cause the precipitate ("pellet") to gather on the | | | | scale processes. Superspeed centrifuges are also |
| bottom of the tube. The remaining solution is | | | | used for purifying cells and nuclei, but in larger |
| properly called the "supernate" or "supernatant | | | | quantities. These centrifuges are used to purify |
| liquid". The supernatant liquid is then either quickly | | | | 25-30 mL of solution within a tube. Additionally, |
| decanted from the tube without disturbing the | | | | larger centrifuges also reach higher angular |
| precipitate, or withdrawn with a Pasteur pipette. | | | | velocities (around 30000 rpm) and also use a |
| The rate of centrifugation is specified by the | | | | larger rotor. |
| acceleration applied to the sample, typically | | | | When Dr. Ivan Sorvall, Beckman and IEC |
| measured in revolutions per minute (RPM) or g. | | | | (International Equipment Company) came up with |
| The particles' settling velocity in centrifugation is a | | | | their "Low Speed" and "Super Speed" class |
| function of their size and shape, centrifugal | | | | centrifuges these centrifuges have been the |
| acceleration, the volume fraction of solids present, | | | | primary fixed (EXPENSIVE) purchase in almost |
| the density difference between the particle, and | | | | every lab. |