The ultracentrifuge is an instrument designed for rotating an object around a fixed axis while applying a perpendicular force. Ultracentrifugation is carried out at speed faster than 20,000 rpm and is used to separate tiny particles from one another in order to determine their sizes and molecular weights. It is also widely used to study high polymers, particularly proteins, nucleic acids, viruses, and other biological macromolecules. There are preparative and analytical ultracentrifuges, and both are used in polymer science, biochemistry, and molecular biology.

A preparative ultracentrifuge is used to isolate specific particles for reuse. It is considered to be a high-performance instrument that is reliable and efficient, and operates quickly and quietly. It features a variety of rotors that are suitable for a range of separation tasks used in cell biology, biochemistry, and molecular biology. A sample can be spun at a high speed until its components separate, which can then be isolated. Most preparative ultracentrifuge units include automatic rotor-life management, a color LCD screen, and positive-feedback capabilities.

Analytical centrifugation is a widely used biomolecular research technique that measures the physical properties of sedimenting particles and the way they behave in a solution state. Theodor Svedberg invented the analytical ultracentrifuge and won the Nobel Prize in Chemistry for the research he conducted with it. In this type of ultracentrifuge, a sample is centrifuged in a cell, and an optical system projects an image of the cell on a computer or film in real time. The most common types of analytical ultracentrifuge experiments are those in sedimentation velocity and equilibrium, which offer information about the shapes, sizes, and conformational changes of macromolecules.

There are dangers associated with the use of an ultracentrifuge because it operates at very high speeds and often uses solutions that involve harsh chemicals. Both of these factors create mechanical stress that can cause rotors to wear out. In addition, rotors must be loaded and balanced correctly, or they can break loose, causing significant damage, injury, and even explosion. Each instrument should receive regular maintenance, and users should be properly trained to load and balance it correctly, and to clean the rotors.