(96c) Electrokinetic Flows in Gradient Monoliths | AIChE

(96c) Electrokinetic Flows in Gradient Monoliths

Authors 

Ivory, C. F. - Presenter, Washington State University


When a pressure gradient is applied across an open capillary, the resulting parabolic flow causes a dramatic dispersion of solutes in that tube. If the same capillary is packed with a monolith or granular stationary phase, then applied pressure and electric fields will generate uniform flows with very low dispersion. However, when electric fields are applied across stationary phases with gradients in fixed charges, the resulting flows can exhibit anomalous behavior, such as flow reversal, which can lead to pathological dispersion during electrofocusing. Because the stationary phase nanopores are roughly the same scale as the Debye length, flows through the mobile and stationary phase are a strong function of charge density, buffer conductivity, and pore size. Because of this, it should be possible to optimize the flow properties for a given separation by adjusting the ionic strength of the running buffer.

This paper will begin with a mathematical model for combined hydraulic- and electrokinetically-driven flows in gradient monoliths and then use that model to predict how these flows vary with the properties of the monoliths and the running buffer. The model will then be used to predict electrofocusing performance on gradient monoliths.