An introduction to particle separations in zonal centrifuges.

Zonal centrifugation, based either on sediInentation rate or on isopycnic banding in liquid density gradients, is useful for high-resolution separation of subcellular particles. However, the amoun t of material which may be separated is extremely limited when conventional centrifuges are employed. To increase the capacity and, in certain instances, the resolution of the method, the possibility of employing largevolume hollow rotors has been explored. These are either loaded and unloaded while spinning or are designed to allow the density gl'adient in the rotor to reorient from a rest position to spin orientation and back with minimal shear and disturbance. The principles of operation and construction of low. speed A series and intermediate-speed B series zonal rotors are reviewed.Nat Cancer Inst Monogr 21: 9-39 1966.