Theoretical relation between the tube zeta potential and the background electrolyte composition in capillary electrophoresis

Abstract

This work presents a theoretical analysis of the relation between the tube zeta potential and the electrolyte solution composition typically found in capillary electrophoresis. A model including the relevant physicochemical parameters of the capillary–solution interface is derived in the framework of Poisson–Boltzmann theory and is then validated experimentally. This model is applied to capillaries containing acidic groups attached to the inner wall as the main source of surface charges. In particular, experimental data of electroosmotic flow in synthetic organic polymer capillaries are considered to prove the validity of the model with less conventional solid materials. It is also found that the model describes successfully experimental data of the zeta potential for a wide range of pH and ionic strength.

Acknowledgements: This research was supported by SEPCYT-FONCyT, PICT 09–09752, and SeCyT-UNL, CAI+D 2002, Argentina. C.L.A.B. and J.A.D. gratefully thank SECyT, CONICET, AAIFQ and the organizing committee of the 11th ICSCS for financial aid.