Effects of cross-sectional change on the isotachphoresis process for protein-separation chip design

Abstract

A 2D finite volume method (FVM)-based computer simulation model has been developed for isotachophoresis (ITP) in three different 20 mm long micro-channels to assist the design of a protein separation chip. The model is based on three major equations, i.e. the mass conservation, charge conservation and electro-neutrality equations. In this study, the ITP system has four negatively-charged components, namely, hydrochloric acid, caproic acid, acetic acid, and benzoic acid, and one positively-charged component, namely, histidine, for use as a background electrolyte (BE). The calculations were performed under the action of a nominal electric field of −5,000 V/m. For the validation of our model, the results of our simulation in a straight channel are compared with the results of a 1D-based open program (SIMUL5), and all the physicochemical properties are obtained from the SIMUL5. Unlike 1D ITP separation, spatially-changed micro-channel shapes provided different separation and moving times as well as a quasi steady state time compared to the 1D results obtained during the ITP process. Dispersion analysis is also conducted using a 2D moment analysis to investigate the effect of 2D geometries on ITP separation.