Automated microgradient system for capillary electrochromatography

Kahle, Vladislav; Vazlerova, Miroslava; Welsch, Thomas

doi:10.1016/s0021-9673(02)01806-x

Cited by 19 publications

(10 citation statements)

References 29 publications

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“…Kahle et al refined the heart-cut technique they introduced previously [41] for sample injection in monolithic CEC columns and studied the key parameters affecting the injection [42]. The fully automated technique is simple and in addition to sample introduction it also enables gradient elution.…”

Section: Reversed Phase Separationsmentioning

confidence: 99%

Recent developments in the field of monolithic stationary phases for capillary electrochromatography

Švec¹

2005

J of Separation Science

219

143

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This review summarizes the contributions to the rapidly growing area of monolithic columns based on both silica and synthetic polymers for capillary electrochromatography and chip electrochromatography, with a focus on those published during the year 2004. A wide variety of both modified approaches to the "old" monoliths and new monoliths have been reported despite the very short period of time covered. This demonstrates that monolithic stationary phases have become a well-established format in the field of electrochromatography. The simplicity of their preparation as well as the good control over their porous properties and surface chemistries make the monolithic separation media an attractive alternative to capillary columns packed with particulate materials.

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Section: Reversed Phase Separationsmentioning

confidence: 99%

Recent developments in the field of monolithic stationary phases for capillary electrochromatography

Švec¹

2005

J of Separation Science

219

143

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“…This may explain the often observed phenomenon that such capillaries have lower plate numbers than capillaries that are homogeneously filled. Several authors have speculated on possible reasons for peak distortion under these circumstances and also presumed changes in the EOF at the interface to be responsible [1,9,22,23]. The fact that the disturbation of the flow occurs in such capillaries at the moment of detection is especially bothersome.…”

Section: Hydrodynamic Pressure Generated By the Eofmentioning

confidence: 99%

“…Several groups have studied the effect of changes in the stationary and the mobile phase composition on the EOF and the chromatographic performance, mostly for capil-laries [1][2][3][4][5][6][7][8][9], but also for microfluidic chips [2,10]. Bello [5] demonstrated how changes in the composition and the pH of the mobile phase influence the EOF.…”

Section: Introductionmentioning

confidence: 99%

“…There is at least one report were the flows generated independently by the empty and filled sections of a CEC capillary were incompatible to a degree that no stable EOF could be obtained [8]. Best results in terms of reproducibility in CEC were observed with homogeneously filled UV transparent columns, where the optical detection was accomplished in the presence of the stationary phase [9].…”

Section: Introductionmentioning

confidence: 99%

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Study of the electroosmotic flow as a means to propel the mobile phase in capillary electrochromatography in view of further miniaturization of capillary electrochromatography systems

Szekeres

Freitag

2005

Electrophoresis

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In this paper, we investigate the phenomenon of electroosmosis as a means to propel a mobile phase, in particular in view of an application in microfluidic systems, which are characterized by significantly smaller volumes of the reservoirs and the separation channels compared to conventional instrumentation. In the microfluidic chip, pH changes due to water electrolysis quickly showed an effect on the electroosmotic flow (EOF), which could be counteracted by either regularly exchanging or buffering the mobile phase. Surface treatment was of no effect in regard to EOF stabilization in empty channels but may have an influence in channels filled with a charged monolith. In fused-silica capillaries the EOF was generally found to decrease from 'naked' to surface-treated to monolith-filled capillaries. The EOF tended to be higher when an organic solvent (acetonitrile) was added to the mobile phase and could be further increased by substituting the water with equal amounts of methanol. In addition, the hydrostatic pressure exerted by the EOF was investigated. In a microfluidic chip with empty (cross-)channels such an effect could be responsible for a redirection of the flow. In capillaries partially filled with a noncharged (non-EOF-generating) monolith, a linear relationship could be established between the EOF created in the empty section of the capillary (apparent mobility) and the length of the monolith (backpressure). In capillaries partially filled with a charged (EOF-producing) monolith, flow inhomogeneities must be expected as a consequence of a superimposition of hydrodynamic pressure and EOF as mobile phase driving force.

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“…A variety of different gradient installations have been reported [19][20][21][22][23][24]. International Union of Pure and Applied Chemistry (IUPAC) recommendations on the terminology for analytical capillary electromigration techniques are available [25].…”

Section: Introductionmentioning

confidence: 99%

Dynamic electric field assisted multi-dimensional liquid chromatography of biological samples

Hennessy

Quaglia

Kornyšova

et al. 2005

Journal of Chromatography B

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Automated microgradient system for capillary electrochromatography

Cited by 19 publications

References 29 publications

Recent developments in the field of monolithic stationary phases for capillary electrochromatography

Recent developments in the field of monolithic stationary phases for capillary electrochromatography

Study of the electroosmotic flow as a means to propel the mobile phase in capillary electrochromatography in view of further miniaturization of capillary electrochromatography systems

Dynamic electric field assisted multi-dimensional liquid chromatography of biological samples

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