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

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)

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

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

Solution Stagnant Layer Back flow Electroosmotic flow

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.

Parametric Study

Parametric Study

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.