Gradient design to optimize rate zonal separations

Lynn Churchill, Gary Banker, Carl W. Cotman

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


An approach to the design of gradients which maximize resolution is developed by analyzing the sedimentation of particles in linear sucrose gradients. Our analysis establishes the fundamental principles of rate separations. These principles can assist in the successful design of preparative centrifugation procedures. Rate separations are always optimal in homogeneous media or very shallow gradients of low density. In homogeneous media, resolution of particles which differ only in sedimentation coefficients is determined by the ratio of their sedimentation coefficients. Particles whose sedimentation properties oppose each other can, under certain conditions, not separate or barely separate unless conditions are carefully selected. Particle populations which differ more in density than in sedimentation coefficients clearly separate better by rate than by isopycnic banding. Rate separations in gradients are considerably improved in a type of gradient where the viscosity decreased as the density increased.

Original languageEnglish (US)
Pages (from-to)370-382
Number of pages13
JournalAnalytical Biochemistry
Issue number2
StatePublished - Dec 1973
Externally publishedYes

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology


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