Transient velocity sedimentation of cells at unit gravity.

A new kinetic method (TRANS-VELS) is described which allows for the first time the accurate determination of the sedimentation velocity of cells at unit gravity. This is accomplished by repetitive optical scanning of the cell distribution as a function of time and during transport through a shallow density gradient. Computer analysis of the statistical moments of the distribution is utilized for the measurement of the sedimentation velocity, its dispersion and the expected resolution. The latter two parameters being strongly time dependent have been estimated for the first time from kinetic data and bear important implications in the widely practiced preparative separation of cells by velocity sedimentation at unit gravity.