Temperature effects in capillary electrophoresis. 1: Internal capillary temperature and effect upon performance

Knox, John H.; McCormack, K. A.

doi:10.1007/bf02290338

Cited by 184 publications

(167 citation statements)

References 15 publications

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“…In the limit of a thin electrical double layer, the EO velocity, u i, slip , calculated from the Helmholtz-Smoluchowski formula acts as a "slip" boundary condition [5,[29][30][31],…”

Section: Temperature and Flow Profiles Of The Fluid In Each Regionmentioning

confidence: 99%

“…1) where the heat transfer condition is uniform along the length direction, Joule heating produces a parabolic-like temperature profile across the capillary column [4][5][6][7][8][9][10][11][12][13][14][15][16]. The internal wall temperature T iw and the temperature difference between the center and the internal wall DT i can be derived from the governing equations [13,15],…”

Section: Temperature and Flow Profiles Of The Fluid In Each Regionmentioning

confidence: 99%

“…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: 97%

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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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“…In the limit of a thin electrical double layer, the EO velocity, u i, slip , calculated from the Helmholtz-Smoluchowski formula acts as a "slip" boundary condition [5,[29][30][31],…”

Section: Temperature and Flow Profiles Of The Fluid In Each Regionmentioning

confidence: 99%

Section: Temperature and Flow Profiles Of The Fluid In Each Regionmentioning

confidence: 99%

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Band-broadening in capillary zone electrophoresis with axial temperature gradients

Xuan

2005

Electrophoresis

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“…The radial temperature profile is usually not strong enough to engender additional significant dispersion due to macroscopic flow heterogeneity [37,122].…”

Section: Effect Of Mobile Phase Ionic Strength On Separation Efficiencymentioning

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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“…Consequently, the CMC as well as the viscosity of the mobile phase are affected and serious problems with poor reproducibility are introduced. (ii) The CMC is influenced by the surfactant concentration, the pH, and the ionic strength of the running buffer [2][3][4]. All of these factors may induce changes in the micellar structure, and therefore, reduce the reproducibility in MEKC.…”

Section: Introductionmentioning

confidence: 98%

Novel anionic copolymerized surfactants of mixed achiral and chiral surfactants as pseudostationary phases for micellar electrokinetic chromatography

et al. 2004

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One disadvantage of amino acid-based chiral selectors for micellar electrokinetic chromatography (MEKC) is that either they have very low solubility or are insoluble at acidic pHs. In order to increase solubilities at lower pHs, we have synthesized a highly water-soluble achiral surfactant and copolymerized it with an amino acid-based chiral surfactant. These two surfactants were polymerized either separately or at various molar rations of binary solutions, yielding pure molecular or copolymerized surfactant (CoPS), respectively. All surfactants were characterized by use of several analytical techniques prior to using them as novel pseudostationary phases in MEKC. The chromatographic performance of the CoPS in MEKC was tested with chiral and achiral analytes. The highly soluble sulfate head group significantly increased the solubility of amino acid-based CoPS over a wide range of pH. Three chiral binaphthyl derivatives were tested and each surfactant system was found to have different selectivity.

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Temperature effects in capillary electrophoresis. 1: Internal capillary temperature and effect upon performance

Cited by 184 publications

References 15 publications

Band-broadening in capillary zone electrophoresis with axial temperature gradients

Band-broadening in capillary zone electrophoresis with axial temperature gradients

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

Novel anionic copolymerized surfactants of mixed achiral and chiral surfactants as pseudostationary phases for micellar electrokinetic chromatography

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