Analysis of Dynamics of Separation in An Electrical Field Flow Fractionation (EFFF) Separator with Couette Flow

Electrokinetic methods are commonly utilized to separate various biomacromolecules, including proteins, antibiotics and DNA, to name a few. One key separation that is difficult to achieve occurs when the biomacromolecules have similar physicochemical properties (i.e. diffusivities, for instance). Therefore, a useful approach to accomplish this type of separation involves exploiting the electrophoretic mobilities of the biomacromomlecules by applying an electrical field perpendicularly to the system, also known as electrical field flow fractionation (EFFF) (Giddings, 1993). This causes the solute most susceptible to the electrical field to locate faster and closer to the walls of the channel, thus creating an effective separation.

In this presentation, an EFFF separator with Couette flow is modeled using the principles of electrokinetic hydrodynamics (EKHD) to compute effective parameters (i.e. effective velocity and effective diffusivity) that predict the macrotransport, or up-scaled behavior of the system. These transport coefficients are useful to predict optimal separation times to obtain the most efficient operating conditions of the device. Predictions of the optimal time of separation will be validated by solving the dynamics of the concentration within the system for typical cases such as a pulse as an input condition for a variety of molecule properties and operating conditions.

1. Giddings, J. C., Science, 1993, 260, 1456.