Prediction of the location of stationary steady‐state zone positions in counterflow isotachophoresis performed under constant voltage in a vortex‐stabilized annular column

Harrison, Schurie L. M.; Ivory, Cornelius F.

doi:10.1002/jssc.200700243

Cited by 9 publications

(15 citation statements)

References 34 publications

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“…The authors believe this could be due to 1) the albumin reaching concentrations above the solubility limit and precipitating out, or 2) the lack of separation power due to the short length of the microchannel. For instance, using information from Harrison and Ivory 61 to calculate the band length of albumin in an ITP stack results in an albumin band length of ~ 3.4 cm (see Appendix 1). The total length of the separation channel described here is only 3.3 cm indicating a lack of separation power to fully resolve albumin from any of the other sample components.…”

Section: Resultsmentioning

confidence: 99%

Preconcentration and detection of the phosphorylated forms of cardiac troponin I in a cascade microchip by cationic isotachophoresis

et al. 2011

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This paper describes the detection of a cardiac biomarker, cardiac troponin I (cTnI), spiked into depleted human serum using cationic isotachophoresis (ITP) in a 3.9 cm long poly(methyl methacrylate) (PMMA) microfluidic channel. The microfluidic chip incorporates a 100x cross-sectional area reduction, including a 10x depth reduction and a 10x width reduction, to increase sensitivity during ITP. The cross-sectional area reductions in combination with ITP allowedvisualization of lower concentrations of fluorescently labeled cTnI. ITP was performed in both “peak mode” and “plateau mode” and the final concentrations obtained were linear with initial cTnI concentration. We were able to detect and quantify cTnI at initial concentrations as low as 46 ng mL−1 in the presence of human serum proteins and obtain cTnI concentrations factors as high as ~ 9000. In addition, preliminary ITP experiments including both labeled cTnI and labeled protein kinase A (PKA) phosphorylated cTnI were performed to visualize ITP migration of different phosphorylated forms ofcTnI. The different phosphorylated states of cTnI formed distinct ITP zones between the leading and terminating electrolytes. To our knowledge, this is the first attempt at using ITP in a cascade microchip to quantify cTnI in human serum and detect different phosphorylated forms.

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Section: Resultsmentioning

confidence: 99%

Preconcentration and detection of the phosphorylated forms of cardiac troponin I in a cascade microchip by cationic isotachophoresis

et al. 2011

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“…One way to immobilize or at least slow down the stacking boundary movement is to apply a counter flow. The key factor in developing a successful system is getting the right counter flow of the appropriate direction and magnitude [39]. Urbánek et al [40] exploited the application of a continuous hydrodynamic counter pressure for balancing the movement of the ITP boundary during the determination of cationic impurities in ionic liquids.…”

Section: Eks In Capillary Electrophoresismentioning

confidence: 99%

High‐sensitivity capillary and microchip electrophoresis using electrokinetic supercharging

Dawod

Chung

2011

J of Separation Science

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Electrokinetic supercharging (EKS) is considered as one of the most powerful online preconcentration techniques in electrophoresis. It combines the efficient preconcentration power of field-amplified sample injection and the exceptional selective nature of transient isotachophoresis. It has a wide range of applications to different types of analytes ranging from small ions to large proteins and DNA fragments. This comprehensive review--up to date--provides listing for all the works, developments, and advances in EKS. The review will pay particular attention to innovations, new methodologies for manipulation, challenges for improving the detection sensitivity, and various applications of EKS in capillaries and microchips.

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“…Generally, a counterflow is used to stop the stacked band at a predetermined location, and the average velocity of the countercurrent flow should be in between that of a pure leader zone and of a pure trailer zone. Recently, Harrison and Ivory [9] developed an analytical model to predict the location of stationary zone in a countercurrent flow ITP. They also proposed a relationship between the length of the leader zone (L L ) and the counterflow velocity ðv cf Þ as [9] …”

Section: Itp In a Straight Microchannel With Counterflowmentioning

confidence: 99%

“…Recently, Harrison and Ivory [9] developed an analytical model to predict the location of stationary zone in a countercurrent flow ITP. They also proposed a relationship between the length of the leader zone (L L ) and the counterflow velocity ðv cf Þ as [9] …”

Section: Itp In a Straight Microchannel With Counterflowmentioning

confidence: 99%

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A method to determine quasi‐steady state in constant voltage mode isotachophoresis

2011

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Identification of the steady state is very challenging in isotachophoresis (ITP); especially in complex microgeometries, such as dog-leg channels or cross-channel junctions. In this work, an elastic matching method is applied to determine the quasi-steady state in microscale ITP. In the elastic matching method, the similarity between two profiles is calculated by comparing intensity distribution of two images or profiles. To demonstrate this similarity-based analysis technique for ITP, a constant voltage mode ITP model is developed and applied to a five-component ITP system. Hydrochloric acid and caproic acid are used as the leader and terminator, respectively, while histidine is used as the counter-ion. Two sample components, acetic acid and benzoic acid, are separated under the action of an applied electric field in both straight and dog-leg microchannels. This analysis shows that conductivity profiles provide a better measure to determine the quasi-steady state in an ITP process. For a straight microchannel, the quasi-steady state is achieved in less than a minute with a total potential drop of 100 V in a 2 cm long channel. In a straight channel, a true steady state can be achieved for ITP with appropriate countercurrent flow where stationary zones are formed, but the time it takes to reach the steady state is much longer than the without counter flow case. The numerical results indicate that a steady state cannot be reached in a dog-leg microchannel because of sample dispersion and refocusing at and near the intersections and at the branch channels. However, the elastic matching method can be used to determine the quasi-steady state in a dog-leg microchannel.

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Prediction of the location of stationary steady‐state zone positions in counterflow isotachophoresis performed under constant voltage in a vortex‐stabilized annular column

Cited by 9 publications

References 34 publications

Preconcentration and detection of the phosphorylated forms of cardiac troponin I in a cascade microchip by cationic isotachophoresis

Preconcentration and detection of the phosphorylated forms of cardiac troponin I in a cascade microchip by cationic isotachophoresis

High‐sensitivity capillary and microchip electrophoresis using electrokinetic supercharging

A method to determine quasi‐steady state in constant voltage mode isotachophoresis

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