What’s the difference between an analytical ultracentrifuge (AUC) and other centrifuges?

Most centrifuges are preparative (or prep) instruments that perform a separation process on the material under test. The separated material is then generally removed from the instrument and used for further testing.

Analytical ultracentrifuges use an optical system (or systems) to analyze samples in a centrifugal field, measuring the concentration distribution of particles—at specific times and radial distances—as they sediment and diffuse. Data collected can be used to determine sedimentation coefficients, diffusion coefficients and molecular weights, sizes, shapes and interactions of particles.