Theoretical model of electroosmotic flow for capillary zone electrophoresis
- Michigan State Univ., East Lansing, MI (United States)
A mathematical model of electroosmotic flow in capillary zone electrophoresis has been developed by taking into consideration of the ion-selective properties of silica surfaces. The electroosmotic velocity was experimentally determined, underboth constant voltage and constant current conditions, by using the resistance-monitoring method. A detailed study of electroosmotic flow characteristics in solutions of singly charged, strong electrolytes (NaCl, LiCl, KCl, NaBr, NaI, NaNO{sub 3}, and NaClO{sub 4}), as well as the phosphate buffer system, revealed a linear correlation between the {Zeta} potential and the logarithm of the cation activity. These results suggest that the capillary surface behaves as an ion-selective electrode. Consequently, the {Zeta} potential can be calculated as a function of the composition and pH of the solution with the corresponding modified Nernst equation for ion-selective electrodes. If the viscosity and dielectric constant of the solution are known, the electroosmotic velocity can then be accurately predicted by means of the Helmholtz-Smoluchowski equation. The proposed model has been successfully applied to phosphate buffer solutions in the range of pH from 4 to 10, containing sodium chloride from 5 to 15 mM, resulting in nearly 3% error in the estimation of the electroosmotic velocity. 53 refs., 8 figs., 2 tabs.
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- FG02-89ER14056
- OSTI ID:
- 136269
- Journal Information:
- Analytical Chemistry (Washington), Vol. 67, Issue 20; Other Information: PBD: 15 Oct 1995
- Country of Publication:
- United States
- Language:
- English
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