Principles for Microscale Separations Based on Redox-Active Surfactants and Electrochemical Methods
- 25 August 2001
- journal article
- research article
- Published by American Chemical Society (ACS) in Analytical Chemistry
- Vol. 73 (20), 4808-4814
- https://doi.org/10.1021/ac010273s
Abstract
We report principles for microscale separations based on selective solubilization and deposition of sparingly water-soluble compounds by an aqueous solution of a redox-active surfactant. The surfactant, (11-ferrocenylundecyl)trimethylammonium bromide, undergoes a reversible change in micellization upon oxidation or reduction. This change in aggregation is exploited in a general scheme in which micelles of reduced surfactant are formed and then put in contact with a mixture of hydrophobic compounds leading to selective solubilization of the compounds. The micelles are then electrochemically disrupted, leading to the selective deposition of their contents. We measured the selectivity of the solubilization and deposition processes using mixtures of two model drug-like compounds, o-tolueneazo-β-naphthol (I) and 1-phenylazo-2-naphthylamine (II). By repeatedly solubilizing and depositing a mixture that initially contained equal mole fractions of each compound, we demonstrate formation of a product that contains 98.4% of I after six cycles. Because the aggregation states of redox-active surfactants are easily controlled within simple microfabricated structures, including structures that define small stationary volumes (e.g., wells of a microtiter plate) or flowing volumes of liquids (e.g., microfabricated channels), we believe these principles may be useful for the purification or analysis of compounds in microscale chemical process systems. When used for purification, these principles provide separation of surfactant and product.Keywords
This publication has 40 references indexed in Scilit:
- Recovery of surfactant from micellar-enhanced ultrafiltration using a precipitation processPublished by Springer Science and Business Media LLC ,2008
- Use of polyelectrolyte-surfactant complexes in colloid-enhanced ultrafiltrationColloids and Surfaces A: Physicochemical and Engineering Aspects, 1997
- Use of Poly electrolyte-Enhanced Ultra filtration to Remove Chromate from WaterSeparation Science and Technology, 1996
- Surfactant Recovery from Water Using Foam FractionationSeparation Science and Technology, 1996
- Ferrocenyl Surfactants at the Surface of Water: Principles for Active Control of Interfacial PropertiesLangmuir, 1996
- In Situ and Reversible Control of the Surface Activity of Ferrocenyl Surfactants in Aqueous SolutionsLangmuir, 1995
- Mass Transfer in the Mobile and Stationary Phases in Micellar Liquid ChromatographyAnalytical Chemistry, 1992
- Interpretation of retention behaviors of transition metal cations in micellar chromatography using ion-exchange modelAnalytical Chemistry, 1992
- Formation of Copper Phthalocyanine Thin Films by Electrolysis of Surfactants with Ferrocenyl MoietyJournal of the Electrochemical Society, 1989
- Admicellar Chromatography: Separation and Concentration of Isomers Using Two-Dimensional SolventsSeparation Science and Technology, 1988