Protein adsorption-dependent electro-kinetic pore flow: modeling of ion-exchange electrochromatography with an oscillatory transverse electric field.

Electro-kinetic acceleration of protein mass transfer was studied by dynamic chromatographic experiments and computer simulations on IEC with an oscillatory transverse electric field (EF) perpendicular to the mobile-phase flow (pIEEC). The breakthrough behavior of BSA was investigated at different electric current densities. A two-dimensional mathematical model has been established to describe the electro-kinetic convection-diffusion behavior of protein adsorption in a single adsorbent particle. The equation was coupled with the axial dispersion model to simulate the dynamic adsorption process in the pIEEC. The model parameters were determined by independent experiments or calculations. It was found that protein adsorption led to an exponential decrease of intraparticle electro-kinetic flow with increasing protein adsorption. Taking this effect into consideration, the model calculations could well describe dynamic breakthrough curves. Moreover, protein distribution in adsorbents was observed to present excursion along the periodical oscillatory EF direction. At the beginning of pIEEC, intraparticle convection caused by the EF contributed more to the enhancement of dynamic binding capacity. Finally, it was confirmed that both the EOF and electrophoresis contributed to the acceleration of mass transfer.