Changes in mobile phase ion distribution when combining pressurized flow and electric field

Eriksson, Björn; Dahl, Magnus; Andersson, Magnus B. O.; Blomberg, Lars G.

doi:10.1002/elps.200406024

Cited by 8 publications

(3 citation statements)

References 42 publications

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“…The only parameter that significantly can increase t change is therefore the electric field strength E. Thus, a high electric field is desirable when a high effect on the separation is sought. The limitation of the magnitude of the electric field that can be applied over a capillary LC column is mainly set by the current through the column and the Joule heating that the current produces [173,174]. It has been noted that in a column with pressurized flow, the current became unex- pectedly high, which further restricts the EF-LC technique [173,174].…”

Section: Controlling the Retention With Electricitymentioning

confidence: 99%

“…The limitation of the magnitude of the electric field that can be applied over a capillary LC column is mainly set by the current through the column and the Joule heating that the current produces [173,174]. It has been noted that in a column with pressurized flow, the current became unex- pectedly high, which further restricts the EF-LC technique [173,174]. However, it seems to us that the application of electric fields in LC can be of interest for focusing analytes in the beginning of the column after the injection [137].…”

Section: Controlling the Retention With Electricitymentioning

confidence: 99%

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Controlling the retention in capillary LC with solvents, temperature, and electric fields

Jandera

Blomberg

Lundanes³

2004

J of Separation Science

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Once a suitable stationary phase and column dimensions have been selected, the retention in liquid chromatography (LC) is traditionally adjusted by controlling the mobile phase composition. Solvent gradients enable achievement of good separation selectivity while decreasing the separation time as compared to isocratic elution. Capillary columns allow use of other programming parameters, i.e. temperature and applied electric fields, in addition to solvent gradient elution. This paper presents a review of programmed separation techniques in miniaturized LC, including retention modeling and method transfer from the conventional to micro- and capillary scales. The impact of miniaturized instrumentation on retention and the limitations of capillary LC are discussed. Special attention is focused on the gradient dwell volume effects, which are more important in micro-LC techniques than in conventional analytical LC and may cause significant increase in the time of analysis, unless special instrumentation and (or) pre-column flow-splitting is used. The influence of temperature upon retention is also discussed, and applications where the temperature has been actively used for retention control in capillary LC are included together with the instrumentation utilized. Finally the possibilities of additional selectivity control by applying an electric field over a packed capillary LC column are discussed.

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Section: Controlling the Retention With Electricitymentioning

confidence: 99%

Section: Controlling the Retention With Electricitymentioning

confidence: 99%

Controlling the retention in capillary LC with solvents, temperature, and electric fields

Jandera

Blomberg

Lundanes³

2004

J of Separation Science

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“…Recent experiments have demonstrated that another strategy may be implemented with success when the analyte is charged [38][39][40][41][42][43][44][45][46]. This amounts to focusing a targeted analyte by opposing two means of transport within the separative microchannel: a constant one-direction solution flow of average velocity v avg which carries the analyte and a counter-direction electrokinetic force [47][48][49][50][51][52][53][54][55][56][57][58] (which depends on the analyte charge, q = z|e|, and its diffusion coefficient, D) whose intensity increases continuously along the microchannel separation length.…”

Section: Introductionmentioning

confidence: 99%

Theory and computational study of electrophoretic ion separation and focusing in microfluidic channels

Klymenko

Amatore

Sun

et al. 2012

NAMC

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In this work we describe the theory and 2D simulation of ion separation and focusing in a new concept of microfluidic separation device. The principle of the method of ion focusing is classical in the sense that it consists in opposing a hydrodynamic transport ensured by the solution flow to an electrophoretic driving force so that any ionic sample results poised within the microchannel at the point where the two forces equilibrate. The originality of the concept investigated here relies on the fact that thanks to the use of an ion-conducting membrane of variable thickness in electrical contact with the channel the electrophoretic force is varied continuously all along the channel length. Similarly, changing the geometric shape of the membrane allows a facile optimization of the device separation and focusing properties.

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Sensing method based on impedance variation of minicolumn packed with cation-exchanger under electric field

2009

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Voltage-induced impedance variation of the minicolumn (i.d. 0.53 mm, length 2 mm) packed with cation exchanger was investigated to develop a sensing method. An aqueous sample solution containing the metal cations was continuously supplied to the minicolumn during the impedance measurement with the simultaneous application of both alternating current voltage (amplitude, 1.0 V; frequency, 200 kHz to 6 Hz) and direct current (DC) offset voltage (0.1 to 1.0 V). On a complex plane plot, the profile of the column impedance consisted of a semicircle (200 kHz to 100 Hz) and a straight line (<100 Hz), of which slope varied with the magnitude of the applied DC offset voltage (V(DC)). The slope-V(DC) relation depended on the kind of the metal cation and its concentration; in particular, the slope-V(DC) relations of monovalent cations (Na(+) and K(+)) and divalent ones (Mg(2+) and Ca(2+)) were significantly different. With the change in the concentration of minor divalent salt of MgCl(2) or CaCl(2) (60 to 140 microM) in the sample solution containing 10 mM NaCl, the slopes showed almost linear relationships between those with application of V(DC) = 0.1 V and 1.0 V both for magnesium and calcium additions. In the case of plural addition of both MgCl(2) and CaCl(2) to the solution, the data points in the slope(0.1 V)-slope(1.0 V) plot were located between the two proportional lines for single additions of magnesium and calcium, reflecting both the mixing ratio and net concentrations of the divalent cations. Thus, simulations determination of Mg(2+) and Ca(2+) can be attained on the basis of the slope(0.1 V)-slope(1.0 V) relation obtained by the impedance measurements of the minicolumn. Actually, the contents of both magnesium and calcium cations in the bottled mineral waters determined simultaneously using the proposed method were almost equivalent to those obtained by the atomic absorption spectrometric measurement.

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Changes in mobile phase ion distribution when combining pressurized flow and electric field

Cited by 8 publications

References 42 publications

Controlling the retention in capillary LC with solvents, temperature, and electric fields

Controlling the retention in capillary LC with solvents, temperature, and electric fields

Theory and computational study of electrophoretic ion separation and focusing in microfluidic channels

Sensing method based on impedance variation of minicolumn packed with cation-exchanger under electric field

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