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Peak compression and resolution for electrophoretic separations in diverging microchannels
Author(s) -
Ross David,
Ivory Cornelius F.,
Locascio Laurie E.,
Van Cott Kevin E.
Publication year - 2004
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/elps.200406119
Subject(s) - electrokinetic phenomena , channel (broadcasting) , electrophoresis , compression (physics) , resolution (logic) , trailing edge , materials science , mechanics , offset (computer science) , analytical chemistry (journal) , chemistry , physics , nanotechnology , chromatography , telecommunications , artificial intelligence , computer science , composite material , programming language
We report the results of experiments and simulations on electrokinetic flow in diverging microchannels (with cross‐sectional area that increases with distance along the channel). Because of conservation of mass and charge, the velocity of an analyte in the channel decreases as the channel cross‐section increases. Consequently, the leading edge of a band of sample moves more slowly than the trailing edge and the sample band is compressed. Sample peak widths, rather than increasing diffusively with time, can then be controlled by the geometry of the channel and can even be made to decrease with time. We consider the possibility of using this peak compression effect to improve the resolution of electrophoretic separations. Our results indicate that for typical separations that are dispersion limited, this peak compression effect is more than offset by the decreased distance between peaks, and the separation resolution in diverging channels is worse than that found for straight channels at the same applied voltage. For separations in very short channels or at very high field strengths, however, when the separation efficiency is injection limited, the peak compression effect is dominant and diverging channels can then be used to achieve improved separation resolution.