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De Moor T, Lagae L, Van Hoof C, Liu C, Van Roy W. Electric field gradient focusing with electro-osmotic flow to reduce analyte dispersion: Concept and numerical investigation. J Chromatogr A 2023; 1689:463726. [PMID: 36586281 DOI: 10.1016/j.chroma.2022.463726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 12/15/2022] [Accepted: 12/16/2022] [Indexed: 12/30/2022]
Abstract
In proteomics, the need to precisely examine the protein compounds of small samples, requires sensitive analytical methods which can separate and enrich compounds with high precision. Current techniques require a minimal analysis time to obtain satisfactory compound separation where longer analysis time means better separation of compounds. But, molecular diffusion will create broadening of the separated compound bands over time, increasing the peak width, and thus reducing the resolution and the enrichment. Electric field gradient focusing (EFGF) is a separation technique, in which proteins are simultaneously separated and enriched by balancing a gradient electrostatic force with a constant hydrodynamic drag force. Because of this balance, analytes are continuously pushed back to their focusing point, limiting the time-dependent peak broadening due to molecular diffusion. Current EFGF techniques are however still suffering from peak broadening because of flow-profile inhomogeneities. In this paper, we propose to use AC electro-osmotic flow (AC EOF) to create a homogeneous flow in EFGF. The interference between the electric field gradient and the AC EOF was thoroughly analysed and the concept was validated using numerical simulations. The results show that a plug flow is obtained on top of a small, distorted boundary layer. While applying different DC electric fields in the electrolyte, a constant flow velocity can be obtained by including a DC offset to the electrodes generating the AC EOF. The plug flow is then maintained over the whole separation channel length, while an electric field gradient is applied. This way, the flow-induced contribution to peak broadening can be minimized in EFGF devices. By modelling the separation of green fluorescent protein (GFP) and R-Phycoerythrin (R-PE), it was shown that the peak width of separated compounds can be reduced and that the separation resolution can be improved, compared to current EFGF methods.
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Affiliation(s)
- Tinne De Moor
- Department of Electrical Engineering, KU Leuven, Kasteelpark Arenberg 10 postbus 2440, 3001 Leuven, Belgium; IMEC, Kapeldreef 75, 3001 Leuven, Belgium.
| | - Liesbet Lagae
- IMEC, Kapeldreef 75, 3001 Leuven, Belgium; Department of Physics and Astronomy, KU Leuven, Celestijnenlaan 200d - bus 2412, 3001 Leuven, Belgium
| | - Chris Van Hoof
- Department of Electrical Engineering, KU Leuven, Kasteelpark Arenberg 10 postbus 2440, 3001 Leuven, Belgium; IMEC, Kapeldreef 75, 3001 Leuven, Belgium
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Exploring Gradients in Electrophoretic Separation and Preconcentration on Miniaturized Devices. SEPARATIONS 2016. [DOI: 10.3390/separations3020012] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Kenyon SM, Keebaugh MW, Hayes MA. Development of the resolution theory for electrophoretic exclusion. Electrophoresis 2014; 35:2551-9. [PMID: 24916305 DOI: 10.1002/elps.201300572] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2013] [Revised: 05/13/2014] [Accepted: 05/28/2014] [Indexed: 11/11/2022]
Abstract
Electrophoretic exclusion, a technique that differentiates species in bulk solution near a channel entrance, has been demonstrated on benchtop and microdevice designs. In these systems, separation occurs when the electrophoretic velocity of one species is greater than the opposing hydrodynamic flow, while the velocity of the other species is less than that flow. Although exclusion has been demonstrated in multiple systems for a range of analytes, a theoretical assessment of resolution has not been addressed. To compare the results of these calculations to traditional techniques, the performance is expressed in terms of smallest difference in electrophoretic mobilities that can be completely separated (R = 1.5). The calculations indicate that closest resolvable species (Δμmin ) differ by approximately 10(-13) m(2) /Vs and peak capacity (nc ) is 1000. Published experimental data were compared to these calculated results.
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Affiliation(s)
- Stacy M Kenyon
- Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ, USA
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Sheridan E, Hlushkou D, Knust KN, Tallarek U, Crooks RM. Enrichment of Cations via Bipolar Electrode Focusing. Anal Chem 2012; 84:7393-9. [DOI: 10.1021/ac301101b] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Eoin Sheridan
- Department
of Chemistry and
Biochemistry, Center for Electrochemistry, and the Center for Nano-
and Molecular Science and Technology, The University of Texas at Austin, 1 University Station, A5300, Austin,
Texas 78712-0165, United States
| | - Dzmitry Hlushkou
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse,
35032 Marburg, Germany
| | - Kyle N. Knust
- Department
of Chemistry and
Biochemistry, Center for Electrochemistry, and the Center for Nano-
and Molecular Science and Technology, The University of Texas at Austin, 1 University Station, A5300, Austin,
Texas 78712-0165, United States
| | - Ulrich Tallarek
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse,
35032 Marburg, Germany
| | - Richard M. Crooks
- Department
of Chemistry and
Biochemistry, Center for Electrochemistry, and the Center for Nano-
and Molecular Science and Technology, The University of Texas at Austin, 1 University Station, A5300, Austin,
Texas 78712-0165, United States
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Sheridan E, Hlushkou D, Anand RK, Laws DR, Tallarek U, Crooks RM. Label-Free Electrochemical Monitoring of Concentration Enrichment during Bipolar Electrode Focusing. Anal Chem 2011; 83:6746-53. [DOI: 10.1021/ac201402n] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Eoin Sheridan
- Department of Chemistry and Biochemistry, Center for Electrochemistry, and the Center for Nano- and Molecular Science and Technology, The University of Texas at Austin, 1 University Station, A5300, Austin, Texas 78712-0165, United States
| | - Dzmitry Hlushkou
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany
| | - Robbyn K. Anand
- Department of Chemistry and Biochemistry, Center for Electrochemistry, and the Center for Nano- and Molecular Science and Technology, The University of Texas at Austin, 1 University Station, A5300, Austin, Texas 78712-0165, United States
| | - Derek R. Laws
- Department of Chemistry and Biochemistry, Center for Electrochemistry, and the Center for Nano- and Molecular Science and Technology, The University of Texas at Austin, 1 University Station, A5300, Austin, Texas 78712-0165, United States
| | - Ulrich Tallarek
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany
| | - Richard M. Crooks
- Department of Chemistry and Biochemistry, Center for Electrochemistry, and the Center for Nano- and Molecular Science and Technology, The University of Texas at Austin, 1 University Station, A5300, Austin, Texas 78712-0165, United States
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Sheridan E, Knust KN, Crooks RM. Bipolar electrode depletion: membraneless filtration of charged species using an electrogenerated electric field gradient. Analyst 2011; 136:4134-7. [DOI: 10.1039/c1an15510e] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Breadmore MC, Dawod M, Quirino JP. Recent advances in enhancing the sensitivity of electrophoresis and electrochromatography in capillaries and microchips (2008-2010). Electrophoresis 2010; 32:127-48. [PMID: 21171119 DOI: 10.1002/elps.201000412] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2010] [Revised: 09/15/2010] [Accepted: 09/16/2010] [Indexed: 01/22/2023]
Abstract
Capillary electrophoresis has been alive for over two decades now; yet, its sensitivity is still regarded as being inferior to that of more traditional methods of separation such as HPLC. As such, it is unsurprising that overcoming this issue still generates much scientific interest. This review continues to update this series of reviews, first published in Electrophoresis in 2007, with an update published in 2009 and covers material published through to June 2010. It includes developments in the fields of stacking, covering all methods from field-amplified sample stacking and large volume sample stacking, through to ITP, dynamic pH junction and sweeping. Attention is also given to on-line or in-line extraction methods that have been used for electrophoresis.
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Affiliation(s)
- Michael C Breadmore
- Australian Centre for Research on Separation Science, School of Chemistry, University of Tasmania, Hobart, TAS, Australia.
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Burke JM, Smith CD, Ivory CF. Development of a membrane-less dynamic field gradient focusing device for the separation of low-molecular-weight molecules. Electrophoresis 2010; 31:902-9. [PMID: 20191553 PMCID: PMC2919354 DOI: 10.1002/elps.200900589] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Dynamic field gradient focusing uses an electric field gradient generated by controlling the voltage profile of an electrode array to separate and concentrate charged analytes according to their individual electrophoretic mobilities. This study describes a new instrument in which the electrodes have been placed within the separation channel. The major challenge faced with this device is that when applied voltages to the electrodes are larger than the redox potential of water, electrolysis will occur, producing hydrogen ions (H+) plus oxygen gas on the anodes and hydroxide (OH(-)) plus hydrogen gas on the cathodes. The resulting gas bubbles and pH excursions can cause problems with system performance and reproducibility. An on-column, degassing system that can remove gas bubbles "on-the-fly" is described. In addition, the use of a high capacity, low-conductivity buffer to address the problem of the pH shift that occurs due to the production of H+ on the anodes is illustrated. Finally, the successful separation of three, low-molecular-weight dyes (amaranth, bromophenol blue and methyl red) is described.
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Affiliation(s)
- Jeffrey M Burke
- Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA 99164-2710, USA
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