Peak broadening in capillary zone electrophoresis

Gaš, Bohuslav; Štědrý, Milan; Kenndler, Ernst

doi:10.1002/elps.1150181203

Cited by 117 publications

(65 citation statements)

References 66 publications

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“…It has been long known in capillary electrophoresis that Joule heating can elevate the buffer temperature and disturb the electroosmotic flow causing significant sample dispersion [30][31][32][33]. The effects of Joule heating on fluid temperature and motion in eDEP have been investigated previously [34][35][36][37][38].…”

Section: Introductionmentioning

confidence: 99%

Joule heating effects on electroosmotic flow in insulator‐based dielectrophoresis

et al. 2011

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Joule heating effects on electroosmotic flow in insulator-based dielectrophoresisInsulator-based dielectrophoresis (iDEP) is an emerging technology that has been successfully used to manipulate a variety of particles in microfluidic devices. However, due to the locally amplified electric field around the in-channel insulator, Joule heating often becomes an unavoidable issue that may disturb the electroosmotic flow and affect the particle motion. This work presents the first experimental study of Joule heating effects on electroosmotic flow in a typical iDEP device, e.g. a constriction microchannel, under DC-biased AC voltages. A numerical model is also developed to simulate the observed flow pattern by solving the coupled electric, energy, and fluid equations in a simplified two-dimensional geometry. It is observed that depending on the magnitude of the DC voltage, a pair of counter-rotating fluid circulations can occur at either the downstream end alone or each end of the channel constriction. Moreover, the pair at the downstream end appears larger in size than that at the upstream end due to DC electroosmotic flow. These fluid circulations, which are reasonably simulated by the numerical model, form as a result of the action of the electric field on Joule heatinginduced fluid inhomogeneities in the constriction region.

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Section: Introductionmentioning

confidence: 99%

Joule heating effects on electroosmotic flow in insulator‐based dielectrophoresis

et al. 2011

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“…The reason is a mismatch of the mobility of the analyte ion and that of the co-ion in the BGE. However, this is an oversimplification as demonstrated in the works of the groups of Beckers, Boč ek, Gaš , Poppe, and Vigh (see, e.g., reviews [35][36][37][38] dealing with such dispersion phenomena). An approximation for the plate height due to electromigration dispersion was described by Xu et al [39]:…”

Section: Peak-broadening Due To Electromigration Dispersionmentioning

confidence: 99%

Are the asserted advantages of organic solvents in capillary electrophoresis real? A critical discussion

Porras

Kenndler

2005

Electrophoresis

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Are the asserted advantages of organic solvents in capillary electrophoresis real? A critical discussionBackground electrolytes (BGEs) prepared in pure organic solvents are common alternatives to aqueous BGEs in capillary electrophoresis. Several general advantages of organic solvents over water have been asserted in the literature, namely (i) organic solvents increase the separation selectivity; (ii) organic solvents increase the separation efficiency; (iii) high separation voltages and/or high BGE ionic strengths can be used in organic solvents due to lower electric current compared to water. Related assumptions are that (iv) due to higher field strengths applicable in organic solvents the analysis time is shorter than in aqueous BGEs, and (v) the solubility and/or stability of components (either analytes or BGE chemicals) is higher/better in organic solvents. In the present work, these asserted advantages were critically evaluated based on the physical principles of ion transport and zone dispersion in solution. The result was that many of the above-mentioned general advantages are overestimated or even inexistent; often they have no fundamental basis.

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“…Thus, the lower bound for the theoretical plate height is h ideal = 2D/u m , where u m = L/t is the migration velocity of the species. In practice, however, there are various sources of band broadening that could contribute to s 2 in CZE [1][2][3]. One such source is the Joule heating effect caused by an electric current passing through the buffer solution [4][5][6][7][8][9].…”

Section: Introductionmentioning

confidence: 98%

“…The theoretical plate numbers (solid line), N = L det /(H T 1 H dif ), were calculated with the analytical model presented above without accounting for the contributions to theoretical plate height from injection, detection, and adsorption, etc. [1][2][3]. The dashed line represents the calculated plate…”

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confidence: 98%

Band-broadening in capillary zone electrophoresis with axial temperature gradients

Xuan

2005

Electrophoresis

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It is widely accepted that Joule heating effects yield radial temperature gradients in capillary zone electrophoresis (CZE). The resultant parabolic profile of electrophoretic velocity of analyte molecules is believed to increase the band-broadening via Taylor-Aris dispersion. This typically insignificant contribution, however, cannot explain the decrease in separation efficiency at high electric fields. We show that the additional band-broadening due to axial temperature gradients may provide the answer. These axial temperature variations result from the change of heat transfer condition along the capillary, which is often present in CZE with thermostating. In this case, the electric field becomes nonuniform due to the temperature dependence of fluid conductivity, and hence the induced pressure gradient is brought about to meet the mass continuity. This modification of the electroosmotic flow pattern can cause significant band-broadening. An analytical model is developed to predict the band-broadening in CZE with axial temperature gradients in terms of the theoretical plate height. We find that the resultant thermal plate height can be very high and even comparable to that due to molecular diffusion. This thermal plate height is much higher than that due to radial temperature gradients alone. The analytical model explains successfully the phenomena observed in previous experiments.

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Peak broadening in capillary zone electrophoresis

Cited by 117 publications

References 66 publications

Joule heating effects on electroosmotic flow in insulator‐based dielectrophoresis

Joule heating effects on electroosmotic flow in insulator‐based dielectrophoresis

Are the asserted advantages of organic solvents in capillary electrophoresis real? A critical discussion

Band-broadening in capillary zone electrophoresis with axial temperature gradients

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