Micellar Electrokinetic Focusing Driven by Ion Concentration Polarization


We report selective electrokinetic focusing of neutral (uncharged) compounds from aqueous solution in a process driven by ion concentration polarization (ICP) at an ion permselective membrane. ICP is the simultaneous enrichment and depletion of ions at opposing ends of an ion permselective membrane or bipolar electrode when an electrical voltage is applied across it. In ICP, the electric field gradient present at the boundary of the ion depletion zone (IDZ) has been employed for concentration enrichment and separation of charged species for analysis. While ICP has proven to be a versatile means of focusing charged species, neutral compounds are unaffected by the electric field, thereby limiting its application. This limitation is of particular concern for the evaluation of the purity of food and pharmaceutical products, in which case the enrichment of uncharged compounds prior to analysis is often necessary. We have addressed this need by conferring a pseudo-charge to neutral compounds via their partition into an anionic micellar phase. In combination with ICP, this approach allows for neutral species to be electrokinetically enriched (stacked) and separated to an extent dependent upon the partition coefficient of the micelle-analyte pair. Initial results are presented including the quantitative characterization of micellar electrokinetic focusing by ICP.

3:30 PM | Mechanical Engineering Building (MEC) Rm 205
Friday, January 18, 2019
Professor Robbyn Anand
Iowa State University
Nathan Swami