Zonal Centrifugation

Since the late Professor T. Svedberg began to apply centrifugal force for the study of colloid systems, progress in centrifugation has continued in two parallel directions. The first line of development has produced the analytical ultracentrifuge, which incorporates an optical system for the analysis of small amount of material while it is being centrifuged through a homogeneous medium (the solvent) under ideal conditions. The analytical centrifuge is now widely used not only to characterize molecular weight, but also to give insights into the size, shape, density and the base composition and activity of biopolymers and other macromolecules. The second line of development has produced the preparative centrifuge, which uses centrifugal force to sediment the solid phase of materials. The preparative centrifuge is a simpler instrument and does not have an optical system. However, recent rapid technical progress and development permit the preparative centrifuge not only to completely separate several or all of the components in a mixture, but also to perform analytical measurements. This versatile technique is known as density gradient centrifugation.