Taylor Dispersion in Electrofocusing at Steady-State

The Aris-Taylor formulation for the dispersion coefficient should not be applied to electrophoretic separations where solutes are focused to a steady-state.  Analytic expressions and numerical calculations for dispersion coefficients will be presented for several types of separations where a steady-state or pseudosteady-state exist. In the simplest case where a solute is focused against a linear gradient in a restoring force, dispersion is controlled by two dimensionless groups, a Peclet number, Pe, which characterizes the magnitude of the parabolic component of the flow, and a gradient number, G_f, which depends on the magnitude of the slope of the restoring force. Following a brief summary of the analytic expressions for dispersion in mathematically linear separations, this talk will discuss the nature of dispersion in nonlinear electrophoretic systems.