title: Droplet-based microextraction in the aqueous two-phase system.
abstract: This report is about microfluidic extraction systems based on droplets of aqueous two-phase system. Mass transfer between continuous phase and dispersed droplet is demonstrated by microextraction of ruthenium red in a microfluidic device. Droplets are generated with electrohydrodynamic method in the same device. By comparing brightness in the digital image of a solution with known concentrations of ruthenium red and those of a droplet in the microextraction, ruthenium red concentration was measured along the microextraction channel, resulting in good agreement with a simple diffusion model. The maximum partition coefficient was 9.58 in the experiment with the 70-mm-long-channel microextractor. The method is usable for terminating microextraction by electrohydrodynamic manipulation of droplet movement direction. Droplets of different ruthenium red concentration, 0.12 and 0.24% (w/w) in this experiment, can be moved to desired place of microfluidic system for further reaction through respectively branched outlets. In this study droplet-based microextraction is demonstrated and the mass transport is numerically analyzed by solving the diffusion-dissolution model.
authors.affiliation: Department of Chemical and Biomolecular Engineering and Center for Ultramicrochemical Process Systems, Korea Advanced Institute of Science and Technology, Daejeon 305-701, South Korea.
authors.forename: Young Hoon
authors.initials: YH
authors.lastname: Choi
authors.forename: Young Soo
authors.initials: YS
authors.lastname: Song
authors.forename: Do Hyun
authors.initials: DH
authors.lastname: Kim
mesh_terms: D000645:Ammonium Sulfate / Q000737:chemistry; D005591:Chemical Fractionation / Q000295:instrumentation / Q000379:methods; D004563:Electrochemistry; D007700:Kinetics; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation / Q000379:methods; D010316:Particle Size; D012430:Ruthenium Red / Q000737:chemistry
chemical_list: D012430:Ruthenium Red; D000645:Ammonium Sulfate