Methods for on-line determination and control of electroendosmosis in capillary electrochromatography and electrophoresis

Wanders, BJ Bart; Goor, van de Aaam; Everaerts, FM Frans

doi:10.1016/s0021-9673(00)94202-x

Cited by 17 publications

(3 citation statements)

References 8 publications

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“…During the run, one of the buffer solutions replaces the other one in the capillary column and the time necessary to fill the entire capillary of known length is found from a change in the current (conductivity). Direct weighing of the electrolyte collected from the capillary outlet − can in principle be used for continuous EOF monitoring, but in practice the approach is limited by the sensitivity of the balance. A successful approach for real-time measurement of EOF is based on fluorescence detection of a dye which continuously adds to the solution in a buffer vial as the dye exits the separation column .…”

mentioning

confidence: 99%

Characterization of Nonbonded Poly(ethylene oxide) Coating for Capillary Electrophoresis via Continuous Monitoring of Electroosmotic Flow

1996

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We examined changes in a poly(ethylene oxide) (PEO) coating by continuously monitoring the electroosmotic flow (EOF) in a fused-silica capillary during electrophoresis. An imaging CCD camera was used to follow the motion of a fluorescent neutral marker zone along the length of the capillary. The PEO coating was shown to reduce the velocity of EOF by more than 1 order of magnitude compared to a bare capillary at pH 7.0. However, it did not reduce EOF efficiently at pH 8.2. The coating protocol was important, especially at an intermediate pH of 7.7. Capillary reconditioning with an acidified solution of PEO was necessary in order to create a stable and efficient coating. In all cases we observed a gradual increase of EOF during extended runs, suggesting that the coating is slowly being degraded. The increase of pH in the cathodic (detection-end) buffer reservoir beyond pH ∼8.0, e.g., as a result of electrolysis, had a large impact on the stability of the coating. This phenomenon may be used for the efficient and fast regeneration of the column surface and provides a simpler and more reliable alternative to pressure flushing of the capillary.

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confidence: 99%

Characterization of Nonbonded Poly(ethylene oxide) Coating for Capillary Electrophoresis via Continuous Monitoring of Electroosmotic Flow

1996

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“…Earlier methods have involved weighing the mass of electrolyte solution transferred [84,100,101]; monitoring electric current while an electrolyte with different conductivity is drawn into the capillary by EOF [102]; determining the z-potential from streaming potential measurements [100] or monitoring the migration time of a neutral marker (such as acetone, methanol, ethanol, thiourea, or 1-propanol) [73,101,103,104]. Recent efforts attempted flow sensor constructions by miniaturization of traditional macroflow sensing principles.…”

Section: Methods To Measure Eofmentioning

confidence: 99%

Theoretical and nomenclatural considerations of capillary electrochromatography with monolithic stationary phases

Végvári

Guttman

2006

Electrophoresis

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During the past decade, CEC has been one of the few novel achievements in the field of separation science attracting a wide interest. The technology progress permitted the realization of the long-sought idea to employ an electroosmotically driven flow through the columns improving the separations in terms of both resolution and efficiency. The early practical obstacles related to the use of conventional bead-packed columns have been solved by the introduction of continuous beds, also known as monoliths. Hitherto, various synthesis approaches have been successfully developed producing monolithic beds in situ in capillary columns, sharing similar physical structure built up of tiny particles (in the sub-microm range) that are covalently linked together and to the capillary wall. Parallel with the practical column technology studies, the theory of electrochromatography has been continuously developed, focusing on such basic issues as EOF characterization, separation efficiency, and peak dispersion effects. This review provides a short introduction to the theory of CEC with special attention to monolithic separation beds. The paper also summarizes the latest achievements in CEC and discusses the nomenclature, EOF characteristics, and some specific advantages of monolithic column technology.

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“…Measuring the migration time of a neutral marker is probably the most frequently used method to measure m EEO [10]. A fast method measuring the migration time of three zones of a neutral marker that are hydrodynamically pumped into the capillary provides accurate data for very low electroosmotic mobilities [11].…”

Section: Surface Properties Of a Channel Wall And Electroosmotic Flowmentioning

confidence: 99%

Wall coating for capillary electrophoresis on microchips

Dolnı́k¹

2004

Electrophoresis

134

127

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This review article with 116 references describes recent developments in the preparation of wall coatings for capillary electrophoresis (CE) on a microchip. It deals with both dynamic and permanent coatings and concentrates on the most frequently used microchip materials including glass, poly(methyl methacrylate), poly(dimethyl siloxane), polycarbonate, and poly(ethylene terephthalate glycol). Characterization of the channel surface by measuring electroosmotic mobility and water contact angle of the surface is included as well. The utility of the microchips with coated channels is demonstrated by examples of CE separations on these chips.

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Methods for on-line determination and control of electroendosmosis in capillary electrochromatography and electrophoresis

Cited by 17 publications

References 8 publications

Characterization of Nonbonded Poly(ethylene oxide) Coating for Capillary Electrophoresis via Continuous Monitoring of Electroosmotic Flow

Characterization of Nonbonded Poly(ethylene oxide) Coating for Capillary Electrophoresis via Continuous Monitoring of Electroosmotic Flow

Theoretical and nomenclatural considerations of capillary electrochromatography with monolithic stationary phases

Wall coating for capillary electrophoresis on microchips

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