A method for predicting the location of particles sedimenting in sucrose gradients.

A theory was developed for the calculation of the positions of zones of particles sedimenting through a sucrose gradient. Equations were derived for particles sedimenting through gradients in which the sucrose concentration is (a) a linear function of radius, or (b) a hyperbolic function of radius. Computations were made for both swing-out and zonal rotors. The theory, which is based on direct integration of the sedimentation equation, exploits equations relating (a) the density of sucrose solutions to sucrose concentration and (b) the viscosity of sucrose solutions to sucrose concentration, and also the concept of reduced time (T/2 = S20.w integral of t to w2dt) of Fujita. The required computations may be made using a scientific calculator. Experimental support for the theory was obtained.