Aspects of detection and identification in isotachophoresis

Lemmens, Aag; Verheggen, Tpem Theo; Everaerts, FM Frans

doi:10.1016/s0021-9673(01)90480-7

Cited by 12 publications

(4 citation statements)

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“…In the indirect fluorescence detection (IFD) approach, nonfluorescent analytes are identified indirectly (with minimal or no a priori knowledge of the physicochemical properties) by adding nonreacting fluorescent tracer species. ,,,, In IFD approaches, the fluorescence-labeled species are typically present in trace quantities in the LE or TE buffers and thus contribute negligibly to the local conductivity. This is unlike indirect detection methods that use UV absorption, where the concentration of UV-sensitive species is often on the same order of the buffering ions and can contribute significantly to the local conductivity. ,− …”

Section: Experimental Tools and Detection Methodsmentioning

confidence: 99%

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Isotachophoresis: Theory and Microfluidic Applications

Ramachandran

Santiago

2022

Chem. Rev.

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Isotachophoresis (ITP) is a versatile electrophoretic technique that can be used for sample preconcentration, separation, purification, and mixing, and to control and accelerate chemical reactions. Although the basic technique is nearly a century old and widely used, there is a persistent need for an easily approachable, succinct, and rigorous review of ITP theory and analysis. This is important because the interest and adoption of the technique has grown over the last two decades, especially with its implementation in microfluidics and integration with on-chip chemical and biochemical assays. We here provide a review of ITP theory starting from physicochemical first-principles, including conservation of species, conservation of current, approximation of charge neutrality, pH equilibrium of weak electrolytes, and so-called regulating functions that govern transport dynamics, with a strong emphasis on steady and unsteady transport. We combine these generally applicable (to all types of ITP) theoretical discussions with applications of ITP in the field of microfluidic systems, particularly on-chip biochemical analyses. Our discussion includes principles that govern the ITP focusing of weak and strong electrolytes; ITP dynamics in peak and plateau modes; a review of simulation tools, experimental tools, and detection methods; applications of ITP for on-chip separations and trace analyte manipulation; and design considerations and challenges for microfluidic ITP systems. We conclude with remarks on possible future research directions. The intent of this review is to help make ITP analysis and design principles more accessible to the scientific and engineering communities and to provide a rigorous basis for the increased adoption of ITP in microfluidics.

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Section: Experimental Tools and Detection Methodsmentioning

confidence: 99%

“…This is unlike indirect detection methods that use UV absorption, where the concentration of UV-sensitive species is often on the same order of the buffering ions and can contribute significantly to the local conductivity. 307 , 311 − 314 …”

Section: Experimental Tools and Detection Methodsmentioning

confidence: 99%

Isotachophoresis: Theory and Microfluidic Applications

Ramachandran

Santiago

2022

Chem. Rev.

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“…35 It is however possible to obtain quantitative information from a constant voltage separation through the use of a detector which contains a coulometer which monitors the current in the separation channel. 36 Qualitative information can be obtained from an isotachophoretic separation when a property which is directly proportional to the mobilities of the ionic species is measured. Thus in this work as conductivity detection was used, such information could be obtained from measuring the step heights produced by the different species.…”

Section: Resultsmentioning

confidence: 99%

Bidirectional isotachophoresis on a planar chip with integrated conductivity detection

Prest¹,

Baldock²,

Fielden³

et al. 2002

Analyst

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The use of a miniaturised planar separation device with integrated conductivity detection for performing bidirectional isotachophoresis (ITP) is described. The chips were produced in poly(methyl methacrylate) (PMMA) using a milling procedure. To enable bidirectional ITP the devices were designed to inject samples into the centre of the section channel and incorporated two integrated on-column conductivity detectors, positioned at opposite ends of this channel. When used with a hydrodynamic sample transport system the devices were used for the analysis of a range of small ions: NH4+; Na+; Mg2+; Ca2+; Li+; NO3-; ClO4-; SO4(2-); F-. Results sucessfully achieved included the simultaneous separation of three anions and three cations.

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“…These regimes include: (i) use of the same electrolyte system, containing appropriately chosen chiral selector, in both columns of the separation unit. This separation regime makes use of a high performance index of the separation unit [33] (i.e., in the preparaElectrophoresis 1999, 20, 2786±2793 Separations of enantiomers by preparative ITP 2789 (ii) Electrolyte systems containing different chiral selectors are employed in the columns. This regime can be assumed to provide two-dimensional separations of the enantiomers [19].…”

Section: Preparative Itp Separations Of Enantiomersmentioning

confidence: 99%