Mathematical modelling of adsorption and transport processes in capillary electrochromatography: open-tubular geometry.
A mathematical modelling approach for open-tubular capillary electrochromatography is presented. The spatially one-dimensional model takes into account (i) a coupling of (non)linear adsorption of positively or negatively charged analyte molecules (at a negatively charged capillary inner surface) with the equilibrium electrokinetics at this solid-liquid interface, (ii) mobile phase transport by electroosmosis and pressure-driven flow, as well as (iii) transport of species by electrophoresis and molecular diffusion. Under these conditions the local zeta-potential and electroosmotic mobility become a function of the concentration of the charged analyte. The resulting inhomogeneity of electroosmotic flow through the capillary produces a compensating pore pressure as requirement for incompressible mobile phase flow (i.e., for constant volumetric flow along the capillary). The results of the simulations are discussed in view of the surface-to-volume ratio of the capillary lumen, the analyte concentration (in combination with a Langmuir isotherm for the adsorption process), and buffer effects.
Paces
Martin
M
Department of Chemical Engineering and Center for Nonlinear Dynamics of Chemical and Biological Systems, Prague Institute of Chemical Technology, Prague, Czech Republic. martin.paces@vscht.cz
Kosek
Juraj
J
Marek
Milos
M
Tallarek
Ulrich
U
Seidel-Morgenstern
Andreas
A
D000327:Adsorption; D020374:Chromatography, Micellar Electrokinetic Capillary / Q000295:instrumentation / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D008962:Models, Theoretical; D055672:Static Electricity