Beckman Instruments, Inc.

Jeffrey J Marque

Paul J Voelker

Allen P Minton

A method of controlled centrifugation including automatic determination (before or during a centrifugation run) of the time to reach 'completion' (within specified limits, depending on the criteria adopted) of a centrifugal separation. By simulation, the sample solute concentration distributions are determined and examined periodically. Centrifugation completion is deemed to have been reached based on certain predetermined criteria relating to spatial changes in the sample solute concentration distributions between successive examinations. The positions of the end points of the concentration distributions or band edges of the sample solutes (transitions from regions of sample solutes to regions of no sample solutes) are determined to facilitate resolving spatial changes of the concentration distributions. The position of an end point or band edge is characterized by a specific location along the centrifuge tube where an imaginary boundary exists at which no more than a specific % of the total mass of the solute in the band lies outside said boundary. In order to avoid premature termination of centrifugation before actual equilibrium has been reached as a result of excessive frequent checks of the motion of the concentration distribution because of relatively long time scale in sedimentation, an estimate is provided of a characteristic periodic interval between successive checks of sample solute concentration distributions.

Terminating centrifugation on the basis of the mathematically simulated

Method and apparatus for controlling the angular velocity of a centrifuge tube containing a solute and a solvent to obtain desirable sedimentation behavior and/or diffusion behavior of the solute within the tube during centrifuge operations. In one embodiment, the angular velocity is maintained at a near-maximum value until just before precipitation of a solute component is reached within the tube. The tube angular velocity is then reduced as a function of time so that critical precipitation is approached but never occurs in the tube as the centrifuge process continues. In other embodiments, the net flux of solute particles into a given volume element of the centrifuge tube, or the ratio of net fluxes of two or more solutes into a predetermined volume elements, is caused to be a prescribed function of time. One application of this method is minimization of the time required to obtain a desired density gradient separation by a centrifuge process.

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San Mateo, CA, United States of America

Jeffrey J Marque