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  4. Turning a micromixer into a separation column: The role of minimal surfaces and transversal transport in enhancing the performance of micro/nano Liquid Chromatography
 
research article

Turning a micromixer into a separation column: The role of minimal surfaces and transversal transport in enhancing the performance of micro/nano Liquid Chromatography

Biagioni, Valentina
•
Procopio, Giuseppe
•
Agosta, Lorenzo  
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September 13, 2025
Journal of Chromatography A

Microchannels hosting spatially-periodic supports for the stationary phase have drawn intense attention in Liquid Cromatography (LC) research in the last two decades, with second-generation μPACs (micro-pillar array columns) setting the current limit of separation efficiency both in terms of plate height and flow resistance. Inspired by recent theoretical and experimental results, suggesting that an increased rate of transversal mixing in the mobile phase can significantly reduce the dispersion bandwidth of the analytes, we investigate and numerically predict the separation performance of a capillary LC column hosting a periodic alternate sequence of helicoidal baffles arranged in a Kenics Mixer (KM) configuration. The comparison of the KM-LC column performance with that of packed, random-monolithic, and μPAC columns, carried out by matching the capillary diameter of the KM to the size of the flow-through pores of the other geometries, shows a potential further enhancement of LC efficiency, with a minimal plate height reduced by a factor 3 for an unretained solute, and by a factor 2 for a solute with retention factor k=2 with respect to the best performing columns reported so far. This improved performance is achieved without compromising in terms of pressure losses, as evidenced by the significant reduction in separation impedance observed across all practically relevant flow velocities when compared to other LC technologies. We propose that the performance enhancement of the KM geometry results from a combination of factors: the minimal nature of the helicoidal surface, which influences the rate of viscous dissipation, and the chaotic advection mechanism in the mobile phase, which mitigates the increase in plate height as eluent velocity increases. Specifically, we find that in the KM geometry, the Cm-term of Golay's equation accounting for the mobile phase contribution to axial dispersion scales slower than linearly with the reduced velocity of the eluent, ur, as Cmurα, with α strictly lower than unity.

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Type
research article
DOI
10.1016/j.chroma.2025.466161
Scopus ID

2-s2.0-105009632036

Author(s)
Biagioni, Valentina

Sapienza Università di Roma

Procopio, Giuseppe

Sapienza Università di Roma

Agosta, Lorenzo  

École Polytechnique Fédérale de Lausanne

Isa, Lucio

ETH Zürich

Paratore, Federico

ETH Zürich

Cerbelli, Stefano

Sapienza Università di Roma

Date Issued

2025-09-13

Published in
Journal of Chromatography A
Volume

1758

Article Number

466161

Start page

466161

Subjects

Chaotic flow

•

Kenics mixer

•

Nano-LC

•

Periodic channel

•

Separation impedance

Editorial or Peer reviewed

REVIEWED

Written at

EPFL

EPFL units
Non-EPFL  
Available on Infoscience
July 14, 2025
Use this identifier to reference this record
https://infoscience.epfl.ch/handle/20.500.14299/252186
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