Taylor dispersion in equilibrium gradient focusing at steady state

Free‐flow electrophoresis (FFE) enables the continuous separation and collection of charged solutes, and as a result, it has drawn interest as both a preparative and an analytical tool for biological applications. Recently, a free‐flow counterflow gradient focusing (FF‐CGF) mechanism has been proposed with the goal of improving the resolution and versatility of FFE. To realize this potential, the factors that influence solute dispersion deserve further attention, including the gradient strength and the parabolic profile of the counterflow. Therefore, the goal of this work is to develop a theoretical model to study the interplay between these factors and molecular diffusion. Overall, an asymmetric solute distribution emerges for a wide range of parameters, and this behavior can be characterized with an exponentially modified Gaussian function. Results show that FF‐CGF can achieve high‐resolution separations, with the potential for high‐throughput protein purification. Moreover, this work provides a practical guide for optimizing experimental conditions, as well as a strong framework for understanding and developing FF‐CGF further.

show abstract

“…The concentration profile of the solute distribution can be modeled using the convection‐diffusion equation [23]:

\begin{equation}\frac{{\partial c}}{{\partial t}} + \nabla \cdot \ \left( {{{\bf u}}c} \right) = \ \nabla \cdot \left( {D\nabla c} \right).\end{equation}

where

c

is the concentration of the solute,

{{\bf u}}

is the vector velocity,

D

is the diffusion coefficient, and

\nabla

is the gradient operator. Substituting Eq.…”

Section: Theorymentioning

confidence: 99%

Investigating peak dispersion in free‐flow counterflow gradient focusing

2021

View full text Add to dashboard Cite

show abstract

“…, the potential to create a gradient in u EP can be realized using several different parameters. In modeling, this gradient can be described by

{normalu}_{EP} = μ_{ep} ({normalF}_{0} + {normalF}_{1} normalx false),

where x (m) is the position in the separation channel, F 0 (V/m) represents the initial electric field at the start of the separation channel (at x = 0), and F 1 (V/m 2 ) is the slope of the linear electric field gradient . The earliest example of generating F 1 was by Koegler and Ivory, in their first EFGF device, which varied A along the length of the channel .…”

Section: Theoretical Backgroundmentioning

confidence: 99%

“…Taylor dispersion is defined as the deformation of a solute band as it experiences parabolic flow while moving through a long tube . Figure shows a solute band for gradient electrofocusing that is distorted by Taylor dispersion .…”

Section: Theoretical Backgroundmentioning

confidence: 99%

“…Ivory recently reported that the original Aris–Taylor expression does not hold true for counterflow gradient electrofocusing, because the solute peaks reach a steady state, rather than continuously evolve over time . Instead, Ivory derived an alternative expression as follows:

\frac{D_{c}}{D_{m}} = β \frac{P e^{2}}{G_{f}} normalf (G_{f}) + 1,

where β is a constant of approximately 1/5 and Pe is the Peclet number, which is a dimensionless number that describes the ratio between advective and diffusive transport.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

“…G f is the gradient number, which is another dimensionless number defined by Ivory as

{normalG}_{normalf} = \frac{μ {normalF}_{1} a^{2}}{{normalD}_{normalm}},

where a (m) can be the radius of a capillary, or the height of a microchannel. The f ( G f ) term is a function that can be approximated with the following expression:

f ({normalG}_{normalf} false) = \frac{G_{f}}{normalK + {normalG}_{normalf}},

where K is a constant approximately equal to 60 .…”

Section: Theoretical Backgroundmentioning

confidence: 99%

See 2 more Smart Citations

Counterflow gradient electrophoresis for focusing and elution

Courtney

Ren

2019

Electrophoresis

View full text Add to dashboard Cite

Counterflow gradient electrofocusing uses the bulk flow of a liquid solution to counterbalance the electrophoretic migration of an analyte. When either the bulk velocity or the electrophoretic velocity of the analyte is made to vary across the length of the channel, there exists a unique zero‐velocity point for the analyte. This focusing method enables simultaneous separation and concentration of different analytes. The high resolution and sensitivity achieved are similar to that of isoelectric focusing, which separates analytes based on their isoelectric points, but the key difference is that analytes will instead focus based on their electrophoretic mobility. Dynamically changing the applied voltage or the counterflow rate over time will shift the zero‐velocity point, and therefore allows the focused analytes to pass through a fixed detection point, or elute from the separation channel. Throughout the review, a number of different counterflow gradient techniques will be discussed, along with their recent advancements and potential applications.

show abstract

Mobilization in two‐step capillary isoelectric focusing: Concepts assessed by computer simulation

Thormann,

Mosher

2023

Electrophoresis

View full text Add to dashboard Cite

The mobilization step in a two‐step capillary isoelectric focusing protocol is discussed by means of dynamic computer simulation data for systems without and with spacer compounds that establish their zones at the beginning and end of the focusing column. After focusing in an electroosmosis‐free environment (first step), mobilization (second step) can be induced electrophoretically, by the application of a hydrodynamic flow, or by a combination of both means. Dynamic simulations provide insight into the complexity of the various modes of electrophoretic mobilization and dispersion associated with hydrodynamic mobilization. The data are discussed together with the relevant literature.

show abstract

Taylor dispersion in equilibrium gradient focusing at steady state

Cited by 5 publications

References 27 publications

Investigating peak dispersion in free‐flow counterflow gradient focusing

Investigating peak dispersion in free‐flow counterflow gradient focusing

Counterflow gradient electrophoresis for focusing and elution

Mobilization in two‐step capillary isoelectric focusing: Concepts assessed by computer simulation

Contact Info

Product

Resources

About