Microscale extraction and phase separation using a porous capillary
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Author(s)
Phillips, T
Bannock, JH
de Mello, JC
Type
Journal Article
Abstract
We report the use of a porous polytetrafluoroethylene capillary for the inline separation of liquid–liquid segmented flows, based on the selective wetting and permeation of the porous capillary walls by one of the liquids. Insertion of a narrow flow restriction at the capillary outlet allows the back pressure to be tuned for multiple liquid–liquid combinations and flow conditions. In this way, efficient separation of aqueous–organic, aqueous–fluorous and organic–fluorous segmented flows can be readily achieved over a wide range of flow rates. The porous-capillary-separator enables the straightforward regeneration of a continuous flow from a segmented flow, and may be applied to various applications, including inline analysis, biphasic reactions, and purification. As a demonstration of the latter, we performed a simple inline aqueous–organic extraction of the pH indicator 2,6-dichloroindophenol. An aqueous solution of the conjugate base was mixed with hydrochloric acid in continuous flow to protonate the indicator and render it organic-soluble. The indicator was then extracted from the aqueous feed into chloroform using a segmented flow. The two liquids were finally separated inline using a porous PTFE capillary, with the aqueous phase emerging as a continuous stream from the separator outlet. UV-visible absorption spectroscopy showed the concentration of indicator in the outflowing aqueous phase to be less than one percent of its original value, confirming the efficacy of the extraction and separation process.
Date Issued
2015-06-09
Date Acceptance
2015-05-19
Citation
Lab on a Chip, 2015, 15, pp.2960-2967
ISSN
1473-0197
Publisher
Royal Society of Chemistry
Start Page
2960
End Page
2967
Journal / Book Title
Lab on a Chip
Volume
15
Copyright Statement
© The Royal Society of Chemistry 2015. This Open Access Article is licensed under a Creative Commons Attribution 3.0 Unported Licence
License URL
Publication Status
Published