Numerical simulation for capillary electrophoresis: II. Relaxation effect of potential gradient in capillary zone electrophoresis

• Published in: Journal of Chromatography A Vol. 838; no. 1; pp. 19 - 29
• Main Authors: Ikuta, Natsuki, Sakamoto, Hiromi, Yamada, Yuji, Hirokawa, Takeshi
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 09-04-1999
• Subjects: Computer simulation; Potential gradients
• ISSN: 0021-9673
• DOI: 10.1016/S0021-9673(99)00117-X

Using our simulation program for CE based on partial differential equations of unsteady state, we found the phenomena at the initial stage of the capillary zone electrophoretic process that a transient zone with very high potential gradient was produced at the front-end of the sample plug and consequently the potential gradient of the rest part without samples decreased. The potential gradient of the zone and the rest part gradually reached the averaged potential gradient (relaxation of potential gradient). This phenomena causes delay of migration time to some degree affecting its reproducibility. This effect is due to discontinuities of the CE system and low mobility of a counter ion in a background electrolyte (BGE). Therefore, in order to improve the delay, discontinuities of solution should be minimized or a counter ion with high mobility in BGE should be selected.