Steady-State Variants of Sc Methods Isoelectric Focusing and Isopycnic Sedimentation

10 STEADY-STATE VARIANTS OF Sc METHODS ISOELECTRIC FOCUSING AND ISOPYCNIC SEDIMENTATION 

This expression is equivalent to Eq. 6.14 with n = 1. Since the force (and consequently the velocity) is focused toward y = 0, a solute will tend to seek out and settle about y = 0, forming a steady-state concentration profile centered on that point. If the position of the minimum for each solute component is different, the components will separate into distinct zones, each centered around its unique focusing position. Rather spectacular separations can result. 

Components cannot be focused around different points by a single 

We found earlier that transient (nonsteady-state) sedimentation required density gradients to stabilize against convection. Isopycnic sedimentation relies on density gradients not only for anticonvective purposes but also as the secondary gradient needed to establish steady-state conditions. The difference in the two cases is found in the magnitude of the density gradient and in the degree to which components are allowed to approach their steady-state condition. The equipment is similar the zonal rotor developed by Anderson is used for isopycnic as well as transient zonal separations [45]. 

An integrated treatment of isoelectric focusing and isopycnic sedimentation was presented in 1971 [50] the following is based on that treatment. 

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