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Introduction
The development of a microfluidic chromatographic analyzer for ions in liquid samples enables the analysis of minute amounts of sample with reduced solvent consumption, which is important in e.g., clinical diagnostics and life-science research. Due to the miniaturized column dimensions, it is crucial to minimize extra-column contributions to maintain high separation efficiencies. We report on the advances in the development of a chip-based platform for ion-exchange separations with minimal dead volumes. This modular microfluidic platform features three stacked chips, i.e., a module comprising the separation channel packed with anion-exchange particles (1), which is hyphenated with a chemically-regenerated microfluidic membrane suppressor chip (2), and a chip module featuring on-chip conductivity detection (3).
Methods
Chips were fabricated with a micro-milling robot using cyclic olefin copolymer and PEEK as substrate materials. The separation module was irreversibly sealed via solvent-vapor-assisted bonding and packed with 7.5 µm anion-exchange particles. The suppressor chip module featured a 127 µm thick membrane between the eluent and regenerant microchannels, to exchange K+ for H+ ions. In addition, a novel electrode design was developed which allows to perform for conductivity detection.
Results
A solvent-vapor-assisted bonding approach was optimized for irreversible sealing of COC microchips, allowing maximum operation pressures up to 300 bar. The in-situ synthesis of polymer monolithic frits in the 0.5 x 0.5 x 50 mm separation channel has been demonstrated, followed by packing with 7.5 µm anion-exchange particles. To align and stack different chip modules while ensuring zero-dead-volume chip-chip connections, and to establish a micro-to-macro interface, a clamp-on chip holder has been constructed. The extra-column contributions induced by the microfluidic membrane suppressor, the detection chip, and the chip-chip connections were assessed. The performance of the chip platform was characterized in both isocratic and gradient-elution mode for the separation of inorganic anions. Operational flow rates and temperatures were optimized allowing efficient anion separations, with a reduced plate height below 3. Selected design and operating conditions of the chemically regenerated membrane suppressor allowed the use of ion strengths up to 80 mM potassium hydroxide and the hypenation with on-chip conductivity detection. Finally, a design for a fully integrated IC chip was presented as an alternative to a stacked layer/module approach.
Novel aspects: First demonstration of a fully integrated chip for ion-exchange separations, featuring separation, eluent suppression, and on-chip detection.
The development of a microfluidic chromatographic analyzer for ions in liquid samples enables the analysis of minute amounts of sample with reduced solvent consumption, which is important in e.g., clinical diagnostics and life-science research. Due to the miniaturized column dimensions, it is crucial to minimize extra-column contributions to maintain high separation efficiencies. We report on the advances in the development of a chip-based platform for ion-exchange separations with minimal dead volumes. This modular microfluidic platform features three stacked chips, i.e., a module comprising the separation channel packed with anion-exchange particles (1), which is hyphenated with a chemically-regenerated microfluidic membrane suppressor chip (2), and a chip module featuring on-chip conductivity detection (3).
Methods
Chips were fabricated with a micro-milling robot using cyclic olefin copolymer and PEEK as substrate materials. The separation module was irreversibly sealed via solvent-vapor-assisted bonding and packed with 7.5 µm anion-exchange particles. The suppressor chip module featured a 127 µm thick membrane between the eluent and regenerant microchannels, to exchange K+ for H+ ions. In addition, a novel electrode design was developed which allows to perform for conductivity detection.
Results
A solvent-vapor-assisted bonding approach was optimized for irreversible sealing of COC microchips, allowing maximum operation pressures up to 300 bar. The in-situ synthesis of polymer monolithic frits in the 0.5 x 0.5 x 50 mm separation channel has been demonstrated, followed by packing with 7.5 µm anion-exchange particles. To align and stack different chip modules while ensuring zero-dead-volume chip-chip connections, and to establish a micro-to-macro interface, a clamp-on chip holder has been constructed. The extra-column contributions induced by the microfluidic membrane suppressor, the detection chip, and the chip-chip connections were assessed. The performance of the chip platform was characterized in both isocratic and gradient-elution mode for the separation of inorganic anions. Operational flow rates and temperatures were optimized allowing efficient anion separations, with a reduced plate height below 3. Selected design and operating conditions of the chemically regenerated membrane suppressor allowed the use of ion strengths up to 80 mM potassium hydroxide and the hypenation with on-chip conductivity detection. Finally, a design for a fully integrated IC chip was presented as an alternative to a stacked layer/module approach.
Novel aspects: First demonstration of a fully integrated chip for ion-exchange separations, featuring separation, eluent suppression, and on-chip detection.
Originele taal-2 | English |
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Titel | The 42nd International Symposium on High Performance Liquid Phase Separations & Related Techniques (HPLC-42), June 21-25, 2015, Geneva, Switzerland. |
Status | Published - 24 jun 2015 |
Evenement | HPLC 2015 - Geneva, Switzerland Duur: 21 jun 2015 → 25 jun 2015 |
Conference
Conference | HPLC 2015 |
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Land/Regio | Switzerland |
Stad | Geneva |
Periode | 21/06/15 → 25/06/15 |
Vingerafdruk
Duik in de onderzoeksthema's van 'Design and characterization of a modular microfluidic platform for ion chromatography with suppressed conductivity detection'. Samen vormen ze een unieke vingerafdruk.Projecten
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SRP6: SRP (Zwaartepunt): exploitatie van de voordelen van de Orde in Opsluiting voor een groenere chemie
Desmet, G., Denayer, J., Denayer, J., Desmet, G. & Denayer, J.
1/11/12 → 31/10/22
Project: Fundamenteel