1. Víctor Rodríguez-Santiago EGEE 520
Study of Electroosmosis in High Temperature Electrophoretic Measurements in Aqueous Solutions
Víctor Rodríguez-Santiago
EGEE 520

2. Background Electrophoresis What?
Movement of charged particles in aqueous solution under the influence of an external electric field.
Uses?
Protein separation, DNA migration studies, contaminant detection and separation.
Electroosmosis
Movement of fluid under the influence of an external electric field. (Undesired in electrophoretic measurements)

3. Background What causes electroosmosis? Electrical Double Layer
Methods to prevent electroosmosis Polymeric coatings
Buffer solutions
Radial electric fields
(Do not work for high temperatures)
Modeling to quantify electroosmosis

4. Governing Equations Using COMSOL™:
Navier-Stokes mode Electrostatic mode
Combined

5. Solution
Stagnant Layer
Back flow
Electroosmotic flow

6. Validation Experimental data was used to validate the model.
With the modeling data, the experimental electrophoretic data can be corrected for electroosmosis.
At pH 7:
Experimental electrophoretic data: 1.76E-8 m2V-1s-1
Electroosmotic modeled data: 2.09E-9 m2V-1s-1
Corrected data: 1.55E-8 m2V-1s-1
The corrected value is well within the confidence value of the experimental data.

7. Parametric Study

8. Parametric Study

9. Concluding Remarks
The COMSOL simulation gives reasonable values for the electroosmotic mobility.
When used to correct for the experimental data, the correction falls within the confidence values.
Either the electroosmotic effect is small or the simulation underestimates its value.