Modeling the velocity field of the electroosmotic flow in charged capillaries and in capillary columns packed with charged particles: interstitial and intraparticle velocities in capillary electrochromatography systems

Liapis, Athanasios I.; Grimes, Brian A.

doi:10.1016/s0021-9673(00)00185-0

Cited by 70 publications

(94 citation statements)

References 38 publications

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“…EOF modeling is a great aid to understand the function of the control parameters. Early general mathematical models tried to describe the velocity field of the EOF in open and packed capillaries [134]. Later an analytical solution was published for hydrophobic rectangular microchannels considering the electrokinetic effect [135].…”

Section: Flow Generation Methodsmentioning

confidence: 99%

New advances in microchip fabrication for electrochromatography

Szekeres

Guttman

2005

Electrophoresis

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There is a great demand in separation technologies for faster and more effective analysis processes. Miniaturization is a suitable technique for satisfying this demand as reduction in size gives increased separation speed with higher efficiency. CEC is an electric-field-mediated separation technique where the liquid flow is generated by the electric field itself. The main advantage of using electric field over pressure for flow generation is the flat flow profile of the EOF; thus, CEC is one of the best candidates to construct a novel and high-efficiency microanalytical device. The aim of the present paper is to review the basic fabrication and bonding principles, as well as connection and system integration options for microfluidics-based electrochromatography. The physical structure and fluidic channel formation are critically evaluated, including glass microstructuring and fusion bonding. Recent developments in nanoflow measurements and the application of various flow control units are also extensively discussed.

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Section: Flow Generation Methodsmentioning

confidence: 99%

New advances in microchip fabrication for electrochromatography

Szekeres

Guttman

2005

Electrophoresis

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“…The influence of a charged capillary inner wall on the radial distribution of EOF velocities may be estimated by [58,75] (6) where I 0 is the zero-order modified Bessel function of the first kind, r eff an effective capillary radius accounting for the no-slip condition at the inner wall of the column, and b characterizes the overall permeability of a bed [76] b 3 a1Àe bed 2 r…”

Section: Electrokinetic Wall Effectmentioning

confidence: 99%

Dynamics of Capillary Electrochromatography: Experimental Study of Flow and Transport in Particulate Beds

et al. 2004

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The chromatographic performance with respect to the flow behavior and dispersion in fixed beds of nonporous and macroporous particles (having mean intraparticle pore diameters of 41, 105, and 232 nm) has been studied in capillary HPLC and electrochromatography. The existence of substantial electroosmotic intraparticle pore flow (perfusive electroosmosis) in columns packed with the macroporous particles was found to reduce stagnant mobile mass transfer resistance and decrease the global flow inhomogeneity over the column cross-section, leading to a significant improvement in column efficiency compared to capillary HPLC. The effect of electroosmotic perfusion on axial dispersion was shown to be sensitive to the mobile phase ionic strength and mean intraparticle pore diameter, thus, on an electrical double layer interaction within the particles. Complementary and consistent results were observed for the average electroosmotic flow through packed capillaries. It was found to depend on particle porosity and distinct contributions to the electrical double layer behavior within and between particles. Based on these data an optimum chromatographic performance in view of speed and efficiency can be achieved by straightforward adjustment of the electrolyte concentration and characteristic intraparticle pore size.

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“…Because of the pluglike flow profile in CEC, the HETP is expected to be smaller, and the velocity of the EOF is a very weak function (i.e., almost independent) of the particles' diameters. Moreover, the film mass transfer coefficient is approximately proportional to the average diameter of the packing material in p-CEC or, in the case of microchannel devices, varies with the size of the channel (8,9). Thus, for electroosmotically driven flows in packed-bed or porous monolithic CEC systems, the film mass transfer coefficient and the intraparticle EOF varies with the size of the interstitial channels for bulk flow.…”

Section: B Ba As Si Ic Cs Smentioning

confidence: 99%

“…The axial dispersion A term for a neutral solute is much smaller Sample cleanup still represents a major bottleneck to using CEC as a than that obtained with a parabolic velocity profile in cap-HPLC. Finally, for particles of a certain pore size, an intraparticle EOF exists that significantly enhances intraparticle mass transfer, and this EOF increases with the average packing material pore diameter and the pore interconnectivity (8,9,36).…”

Section: P Pe Er Rs Sp Pe Ec Ct Ti IV Ve Es Smentioning

confidence: 99%