Displacement electrophoresis

Martin, A.J.P.; Everaerts, F.M.

doi:10.1016/s0003-2670(01)80582-1

Cited by 74 publications

(31 citation statements)

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“…In ITP, analytes simultaneously focus and can separate between a high effective mobility leading electrolyte (LE) ions and low effective mobility trailing electrolyte (TE) ions. When present in sufficient amount, the analytes focus and segregate into distinct, contiguous zones with locally uniform (plateau-like) concentrations [3]. However, when analytes are present in trace quantities, they focus into peaks of width determined by the diffusive interface between neighboring zones.…”

Section: General Aspectsmentioning

confidence: 99%

High‐sensitivity detection using isotachophoresis with variable cross‐section geometry

et al. 2011

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We present a theoretical and experimental study on increasing the sensitivity of ITP assays by varying channel cross-section. We present a simple, unsteady, diffusion-free model for plateau mode ITP in channels with axially varying cross-section. Our model takes into account detailed chemical equilibrium calculations and handles arbitrary variations in channel cross-section. We have validated our model with numerical simulations of a more comprehensive model of ITP. We show that using strongly convergent channels can lead to a large increase in sensitivity and simultaneous reduction in assay time, compared to uniform cross-section channels. We have validated our theoretical predictions with detailed experiments by varying channel geometry and analyte concentrations. We show the effectiveness of using strongly convergent channels by demonstrating indirect fluorescence detection with a sensitivity of 100 nM. We also present simple analytical relations for dependence of zone length and assay time on geometric parameters of strongly convergent channels. Our theoretical analysis and experimental validations provide useful guidelines on optimizing chip geometry for maximum sensitivity under constraints of required assay time, chip area and power supply.

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Section: General Aspectsmentioning

confidence: 99%

High‐sensitivity detection using isotachophoresis with variable cross‐section geometry

et al. 2011

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“…Analytes can focus in two modalities depending on initial analyte concentration as well as focusing rate and time. High initial analyte concentrations and sufficient focusing time result in 'plateau mode', which is characterized by distinct analyte zones each at a locally uniform concentration determined generally by the Jovin and Alberty relations (Alberty 1950;Martin & Everaerts 1970;Jovin 1973). In contrast, sufficiently low initial analyte concentrations lead to 'peak mode' focusing where sample ions accumulate in a sharp peak between neighbouring species (e.g.…”

Section: Introductionmentioning

confidence: 99%

Sample dispersion in isotachophoresis

Garcia-Schwarz¹,

Bercovici²,

Marshall³

et al. 2011

J. Fluid Mech.

115

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We present an analytical, numerical and experimental study of advective dispersion in isotachophoresis (ITP). We analyse the dynamics of the concentration field of a focused analyte in peak mode ITP. The analyte distribution is subject to electromigration, diffusion and advective dispersion. Advective dispersion results from strong internal pressure gradients caused by non-uniform electro-osmotic flow (EOF). Analyte dispersion strongly affects the sensitivity and resolution of ITP-based assays. We perform axisymmetric time-dependent numerical simulations of fluid flow, diffusion and electromigration. We find that analyte properties contribute greatly to dispersion in ITP. Analytes with mobility values near those of the trailing (TE) or leading electrolyte (LE) show greater penetration into the TE or LE, respectively. Local pressure gradients in the TE and LE then locally disperse these zones of analyte penetration. Based on these observations, we develop a one-dimensional analytical model of the focused sample zone. We treat the LE, TE and LE-TE interface regions separately and, in each, assume a local Taylor-Aris-type effective dispersion coefficient. We also performed well-controlled experiments in circular capillaries, which we use to validate our simulations and analytical model. Our model allows for fast and accurate prediction of the area-averaged sample distribution based on known parameters including species mobilities, EO mobility, applied current density and channel dimensions. This model elucidates the fundamental mechanisms underlying analyte advective dispersion in ITP and can be used to optimize detector placement in detection-based assays.

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“…Already the more than a century old pioneering works by Kohlrausch [1] and Weber [2] have described the basic features of these self-sharpening boundaries and the conditions of their formation. Their basic description kept its relevance till the modern times and has become the basis of isotachophoresis (ITP) [3], one of the current capillary electrophoretic methods. The self-sharpening condition for a pair of adjacent zones, each containing a single ionogenic substance and a common counterion, is usually formulated on the basis of effective mobilities as that the effective mobility of the substance of the front zone must be higher than that of the substance of the back zone [4].…”

Section: Introductionmentioning

confidence: 99%

A new type of migrating zone boundary in electrophoresis: 1. General description of boundary behavior based on electromigration dispersion velocity profiles

Gebauer

Boček

2005

Electrophoresis

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Till now two principal types of electrophoretic boundaries have been recognized: a steady-state one showing self-sharpening properties and an unsteady-state one showing electromigration dispersion (EMD). In this contribution, the existence of a third (hybrid) type of electrophoretic boundary is revealed, that shows simultaneously: (i) steady-state character with self-sharpening properties in a certain part of the boundary, demarcated by a certain range of its composition; (ii) unsteady-state character with EMD in the resting part. A new theoretical approach to the study of the structure and properties of electrophoretic boundaries is presented, based on EMD velocity profiles representing the dependence of the EMD velocity on the composition in any point of the transition region across the boundary. According to this approach, the linearity or nonlinearity of the EMD velocity profile is recommended as the criterion for distinguishing the actual type of the boundary in question. It is shown that the new type of electrophoretic boundary is not an exotic case but may be observed even in simple systems as, e.g., formed by adjacent zones containing mixtures of current species such as picrate and acetate. Computer simulations are presented which confirm the theoretical conclusions and illustrate the three types of electrophoretic boundaries.

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Displacement electrophoresis

Cited by 74 publications

References 0 publications

High‐sensitivity detection using isotachophoresis with variable cross‐section geometry

High‐sensitivity detection using isotachophoresis with variable cross‐section geometry

Sample dispersion in isotachophoresis

A new type of migrating zone boundary in electrophoresis: 1. General description of boundary behavior based on electromigration dispersion velocity profiles

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