(10e) Optimal Separation Times In An Electrical Field Flow Fractionation (EFFF) Separator: Effect of Electroosmotic Flow

Separation of biomacromolecules for pharmaceutical processes is a multi-million dollar effort where even the smallest increase in the separation efficiency has a very healthy economical impact on the process or application. Antibiotics, proteins, and DNA are some key examples of biomacromolecules where new techniques and approaches for separation and or characterization are require. Electrokinetic-based methods have been used in a wide variety of applications not only related to separations but also to environmental remediation and drug delivery, to name a few. The difficulty of these methods is the efficient and consistent design of separation protocols due, in part, to the fact that the role of EOF on dispersion of the solute within the channel is not completely understood. These aspects become even more relevant when the dimensionsof the channel are small.

One of the EK-based applications is EFFF. In this separation technique, an orthogonal applied field (i.e. gravitational, electrical, etc.) drives the motion of the charged molecules towards the channel walls; thus, the solute that is most susceptible to the influence of the field locates closest to the walls, and, depending on the solute properties, different species reach the wall at different locations.

In this presentation, the authors will discuss a model that can be applied to an EFFF separation device to determine the effect of electro-osmotic flow on the separation efficiency. In particular, optimal times of separation will be computed and parametrically analyzed for a wide range of values. Principles of electrokinetic hydrodynamics (EKHD, see Arce et al [1]) allow for the connection to the convective-diffusive transport with the aid of the spatial averaging approach. Results of the research effort will predict the effects of electroosmosis on the optimal separation times to design and or optimize an EFFF separation device where electroosmotic flow could play a role.

[1] Arce, P.; M. Oyanader, and J. Pascal, “Electrokinetic-Hydrodynamics (EKHD): An Introductory Graduate level Course.” To be submitted to Chemical Engineering Education.