A method-of-moments formulation for describing hydrodynamic dispersion of analyte streams in free-flow zone electrophoresis

Dutta, Debashis

doi:10.1016/j.chroma.2014.03.018

Cited by 18 publications

(41 citation statements)

References 37 publications

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“…29–31 The miniaturization of FFZE separations to micrometer sized compartments has further enhanced their performance by reducing Joule heating effects, allowing the injection of narrow sample streams as well as minimizing hydrodynamic dispersion of the analyte zones. 32–34 …”

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confidence: 99%

Electrophoretic Extraction of Low Molecular Weight Cationic Analytes from Sodium Dodecyl Sulfate Containing Sample Matrices for Their Direct Electrospray Ionization Mass Spectrometry

2015

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While the use of sodium dodecyl sulfate (SDS) in separation buffers allows efficient analysis of complex mixtures, its presence in the sample matrix is known to severely interfere with the mass-spectrometric characterization of analyte molecules. In this article, we report a microfluidic device that addresses this analytical challenge by enabling inline electrospray ionization mass spectrometry (ESI-MS) of low molecular weight cationic samples prepared in SDS containing matrices. The functionality of this device relies on the continuous extraction of analyte molecules into an SDS-free solvent stream based on the free-flow zone electrophoresis (FFZE) technique prior to their ESI-MS analysis. The reported extraction was accomplished in our current work in a glass channel with microelectrodes fabricated along its sidewalls to realize the desired electric field. Our experiments show that a key challenge to successfully operating such a device is to suppress the electroosmotically driven fluid circulations generated in its extraction channel that otherwise tend to vigorously mix the liquid streams flowing through this duct. A new coating medium, N-(2-triethoxysilylpropyl) formamide, recently demonstrated by our laboratory to nearly eliminate electroosmotic flow in glass microchannels was employed to address this issue. Applying this surface modifier, we were able to efficiently extract two different peptides, human angiotensin I and MRFA, individually from an SDS containing matrix using the FFZE method and detect them at concentrations down to 3.7 and 6.3 µg/mL, respectively, in samples containing as much as 10 mM SDS. Notice that in addition to greatly reducing the amount of SDS entering the MS instrument, the reported approach allows rapid solvent exchange for facilitating efficient analyte ionization desired in ESI-MS analysis.

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confidence: 99%

Electrophoretic Extraction of Low Molecular Weight Cationic Analytes from Sodium Dodecyl Sulfate Containing Sample Matrices for Their Direct Electrospray Ionization Mass Spectrometry

2015

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“…The amount of heat released is related to the voltage, V, electric current, I, and the resistance of the respective media, R, in the following ways: Q  V 2 /R = I 2 R. In FFE, the heat is generated within the electrolyte, thus increasing the electrolyte temperature and possibly leading to boiling. Recently, Dutta estimated, through computation, the effects of Joule heating on the quality of separation [47]. In general, Joule heating and its consequences can easily destroy steady-state purification in FFE.…”

Section: Joule Heatingmentioning

confidence: 99%

Advances in steady-state continuous-flow purification by small-scale free-flow electrophoresis

Agostino

Krylov

2015

TrAC Trends in Analytical Chemistry

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“…[19] The same principles are routinely applied to simplify the mathematical description of solute profiles in catalytic beds [20], chromatography columns [21], and microchannels. [3] Second, the development of an analytic expression can be carefully checked for errors; third, the derived formula provides a theoretical framework for developing correlations in similar systems which do not admit an analytic form; fourth, the exact solution allows an asymptotic check on the precision and accuracy of computer simulations of analytically intractable models; and, finally, the methodology used to obtain this analytic solution can be adapted to extract information from tractable variations on this model. Electrophoresis This article is protected by copyright.…”

Section: Introductionmentioning

confidence: 99%

“…Soon after this, Aris [2] formalized a mathematical treatment of the model equation and extended its solution to include the axial diffusion term and to allow its application to conduits of constant but arbitrarily-shaped cross-section. In dimensionless form, the expression for dispersion in a tube is Variations on this formula [3,4] are frequently applied in the design [5,6] of separation columns or the analysis [7,8] of experimental data and, while they should Electrophoresis This article is protected by copyright. All rights reserved.…”

Section: Introductionmentioning

confidence: 99%

Taylor dispersion in equilibrium gradient focusing at steady state

Ivory

2015

Electrophoresis

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An analytic expression is presented for the effective dispersion coefficient in the case where a solute is focused in a parabolic flow against a linear gradient in a restoring force. This expression was derived by employing a minor variation on the method of moments used by Aris in his development of the dispersion coefficients for a time-dependent, isocratic system. In the present case, dispersion is controlled by two dimensionless groups, a Peclet number which is proportional to the parabolic component of the flow, and a gradient number which is proportional to the slope of the restoring force. These results confirm that the Aris-Taylor expression for the dispersion coefficient should not be applied in cases where a solute is focused to a stationary steady state.

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A method-of-moments formulation for describing hydrodynamic dispersion of analyte streams in free-flow zone electrophoresis

Cited by 18 publications

References 37 publications

Electrophoretic Extraction of Low Molecular Weight Cationic Analytes from Sodium Dodecyl Sulfate Containing Sample Matrices for Their Direct Electrospray Ionization Mass Spectrometry

Electrophoretic Extraction of Low Molecular Weight Cationic Analytes from Sodium Dodecyl Sulfate Containing Sample Matrices for Their Direct Electrospray Ionization Mass Spectrometry

Advances in steady-state continuous-flow purification by small-scale free-flow electrophoresis

Taylor dispersion in equilibrium gradient focusing at steady state

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