Analysis of separation efficiency in capillary electrophoresis with direct control of electroosmosis by using an external electric field

Lee, Cheng S.; Wu, Chin-Tiao; Lopes, Teresa I. M. S.; Patel, Bhisma K.

doi:10.1016/0021-9673(91)80065-o

Cited by 34 publications

(21 citation statements)

References 5 publications

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“…They have found that for the effective EOF regulation at practically achievable intensities of radial electric field up to 3610 8 V/m, the pH of the BGE should be below 5, and the separations should be performed at low ionic strength BGEs in small id capillaries. On the other hand, Hartley and Hayes [38] examined two basic theoretical models of the EVC of EOF in CE, particularly the electrostatic cylindrical capacitor model [23,39] and Gaussian model [40], and came to a conclusion that none of these models correlates exactly with the experimental data and that further investigation of the mechanism of the EVC of EOF should be done.…”

Section: Introductionmentioning

confidence: 97%

Control of EOF in CE by different ways of application of radial electric field

et al. 2007

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Various ways of application of radial electric field for the control of electrokinetic potential and EOF in a home-made device for CE are presented. The device comprises three high-voltage power supplies, which are used to form a radial electric field across the fused-silica capillary wall. One power supply provides the internal electric field - a driving force for electrophoretic migration of charged analytes and for the EOF. Two power supplies are connected to the ends of the outer low-conductivity polymeric coating, which is formed by the dispersion of insoluble conductive copolymer of aniline and p-phenylendiamine in polystyrene matrix (dissolved in N-methylpyrrolidone) attached to the original outer polyimide coating of the capillary. They are able to constitute the external longitudinal electric field with variable values of electric potential at both ends of the outer coating. The potential gradient between the external and internal electric field is perpendicular to the capillary wall and forms a radial electric field across the capillary wall, which affects the electrokinetic potential at the solid-liquid interface and EOF inside the capillary. The developed device and methodology has been applied for the analysis of both chiral and achiral molecules such as terbutaline enantiomers and oligopeptides (diglycine and triglycine). The effect of magnitude, orientation, and different ways of application of the radial electric field on the flow rate of the EOF and on the speed, efficiency, and resolution of CZE separations of the above analytes in the internally noncoated fused-silica capillaries have been evaluated.

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Section: Introductionmentioning

confidence: 97%

Control of EOF in CE by different ways of application of radial electric field

et al. 2007

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“…E lectrical field flow fractionation (EFFF) is an effective technique to separate a variety of solutes, including for example, proteins, DNA, and pharmaceuticals, among others (Wang and Flagan, 1990;Lee et al, 1991;Probstein, 1991;Giddings, 1993;Williams and Lee, 2006;Messaud et al, 2009;Gajdos and Brenner, 1978;Heller et al, 1994). However, there is still much work to be done regarding the effects of many of the variables that contribute to these processes.…”

Section: Introductionmentioning

confidence: 98%

Effect of wall velocities on the determination of optimal separation times in electrical field flow fractionation (EFFF)

2010

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Electrical field flow fractionation (EFFF) has two perpendicular driving forces that help to produce an optimal separation of solute in a mixture [Giddings, Science 1993; 260:1456-1465. For Couette flow based devices, the ratio of the velocity of the capillary walls offers an extra parameter that can be exploited to enhance the efficiency of EFFF applications. The analysis of the effects of this parameter on optimal times of separation is the subject matter of this contribution. The use of this additional parameter increases flexibility in the design of new devices for the improvement of the separation of solutes, such as proteins, DNA, and pharmaceuticals, as it will be illustrated with the results of this analysis Trinh et al., 1999). The analysis has been illustrated by selecting parameter values that represent a number of potential useful applications. A set of five parameters (i.e., z, the valence; , electrophoretic mobility; Pe, Peclet number; , the orthogonal applied electrical field; and R, the ratio of channel wall velocities) has been combined to obtain the best operating conditions for optimal separation of solutes. Results indicate that R, the ratio of the channel wall velocities, is actually the most important driving parameter.Le fractionnement de flux de champélectrique (EFFF) a deux forces motrices perpendiculaires qui aidentà produire une séparation optimale d'un soluté dans un mélange [Giddings, Science 1993; 260:1456-1465. Pour les systèmes basés sur le flux Couette, le ratio de la vélocité des parois capillaires offre un paramètre supplémentaire qui peutêtre exploité pour rehausser l'efficience des applications EFFF. L'analyse des effets de ce paramètre sur les temps optimaux de séparation est le thème de ce travail. L'utilisation de ce paramètre supplémentaire rehausse la flexibilité de la conception de nouveaux systèmes pour l'amélioration de la séparation des solutés tels que les protéines, l'ADN et les produits pharmaceutiques, comme cela sera illustré par les résultats de cette analyse. L'analyse aété illustrée en sélectionnant des valeurs de paramètres qui représentent un nombre d'applications utiles potentielles. Un ensemble de cinq paramètres (c.-à-d., z, la valence; la mobilitéélectrophorétique, ; Pe, nombre de Peclet; , le champélectrique orthogonal appliqué et R, le ratio des vélocités des parois de canal) aété combiné pour obtenir les meilleures conditions opératoires pour une séparation optimale des solutés. Les résultats indiquent que R, le ratio des vélocités des parois de canal, est en fait le paramètre moteur le plus important.

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“…Sauer et al [5] introduced a non-trivial and fundamental modeling approach as a tool for the analysis of the system under study. This effort was the first that systematically explained experimental trends [7] in enhancing separation efficiency when an orthogonal field is applied to electrophoretic separations. One limitation of the analysis is that the predicting formulae for the effective transport parameters are in terms of integrals that require numerical solution.…”

Section: Introductionmentioning

confidence: 99%

“…Sauer et al [5], for example, studied this effect on the transport of solute in a Poiseuille flow regime using a capillary channel of rectangular geometry. Before the work reported by Sauer et al [5], only ad hoc expressions were known for dispersion under the effect of an electrical field [18][19][20] and the effects of an orthogonal field were only known experimentally [7,11,21]. Sauer et al [5] introduced a non-trivial and fundamental modeling approach as a tool for the analysis of the system under study.…”

Section: Introductionmentioning

confidence: 99%

“…For example, the effect of the internal structure of the material used in gel electrophoresis [4] and the one of operating parameters, such as the nature of the applied electrical field [5], on the separation efficiency have been recently studied and reported as playing a key role in reducing optimal separation times for biomacromolecules. Motivation for these efforts is rooted in new potential applications that have emerged in, for example, proteomics and genomics [6,7] and in soil cleaning processes [1,8,30], among others.…”

Section: Introductionmentioning

confidence: 99%

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Optimal separation times for electrical field flow fractionation with Couette flows

et al. 2008

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The prediction of optimal times of separation as a function of the applied electrical field and cation valence have been studied for the case of field flow fractionation [Martin M., Giddings J. C., J. Phys. Chem. 1981, 85, 727] with charged solutes. These predictions can be very useful to a priori design or identify optimal operating conditions for a Couette-based device for field flow fractionation when the orthogonal field is an electrical field. Mathematically friendly relationships are obtained by applying the method of spatial averaging to the solute species continuity equation; this is accomplished after the role of the capillary geometrical dimensions on the applied electrical field equations has been assessed [Oyanader M. A., Arce P., Electrophoresis 2005; 26, 2857]. Moreover, explicit analytical expressions are derived for the effective parameters, i.e. diffusivity and convective velocity as functions of the applied (orthogonal) electrical field. These effective transport parameters are used to study the effect of the cation valence of the solutes and of the magnitude of the applied orthogonal electrical field on the values of the optimal time of separation. These parameters play a significant role in controlling the optimal separation time, leading to a family of minimum values, for particular magnitudes of the applied orthogonal electrical field.

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Analysis of separation efficiency in capillary electrophoresis with direct control of electroosmosis by using an external electric field

Cited by 34 publications

References 5 publications

Control of EOF in CE by different ways of application of radial electric field

Control of EOF in CE by different ways of application of radial electric field

Effect of wall velocities on the determination of optimal separation times in electrical field flow fractionation (EFFF)

Optimal separation times for electrical field flow fractionation with Couette flows

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