Volume expansion and loss of sample due to initial self-heating in capillary electroseparation (CES) systems

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

doi:10.1007/bf02269768

Cited by 43 publications

(13 citation statements)

References 2 publications

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“…Such an improvement in the separation efficiency due to the initial voltage ramp was also reported previously in both nonaqueous [36] and aqueous CZE [37][38][39] in uncoated capillaries. In addition, this voltage ramping was shown to avoid the loss of samples that could take place when the rate of thermal expansion of liquid, due to Joule heating, is more rapid than the electromigration rate of the slowest moving solute [40]. It is probably the lower thermal volume expansion, as suggested by Palonen et al [35], that improves the electrophoretic separation in the presence of an initial voltage ramp.…”

Section: Introductionmentioning

confidence: 95%

Joule heating effects on separation efficiency in capillary zone electrophoresis with an initial voltage ramp

Xuan

2006

Electrophoresis

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An analytical model is developed to quantify the Joule heating effects on the separation efficiency in CZE with an initial voltage ramp. This model considers the temporal variations of nonuniform temperature and flow fields in the course of voltage ramping. The temperature dependence of electrical conductivity, dynamic viscosity, and mass density of the fluid is also taken into account. We demonstrate that the application of an initial voltage ramp delays the development of pressure-driven flows induced passively by the axial temperature gradients. The thermal dispersion is thus significantly reduced, resulting in a higher theoretical plate number in CZE. Such improvement in the separation efficiency is apparent in noncoated capillaries at high electric fields with an appropriate voltage ramp-up time. These predictions are consistent with previous observations in both aqueous and nonaqueous CZE that took place in uncoated capillaries. In coated capillaries where the EOF is suppressed, however, our model predicts a lower plate number in the presence of an initial voltage ramp.

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Section: Introductionmentioning

confidence: 95%

Joule heating effects on separation efficiency in capillary zone electrophoresis with an initial voltage ramp

Xuan

2006

Electrophoresis

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“…The sample plug was bracketed by a presample plug of water (0.5 psi65 s) and a postsample plug of buffer (0.5 psi615 s). The water plug implemented an on-line sample preconcentration mechanism [27] and the postsample plug (together with the voltage ramp [28]) prevented sample loss due to thermal expansion of the sample plug. Sample overloading effect (e.g., peak tailing and low number of theoretical plates) have been distinguished from the slow kinetics of sample-capillary wall interaction by pressure-driven runs (runs in the absence of applied voltage).…”

Section: Cementioning

confidence: 99%

Capillary electrophoresis of cationic random coil peptide standards: Effect of anionic ion‐pairing reagents and comparison with reversed‐phase chromatography

2004

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The present study compares a charge/hydrophobicity capillary electrophoresis (CE) approach to reversed-phase high-performance liquid chromatography (RP-HPLC) for the separation of three series of four synthetic, random coil peptide standards. Each series has peptides of the same positive charge (+1, +2 and +3 series) and length but differing in hydrophobicity. Complete resolution of the 12 peptides was achieved via a novel CE approach: a capillary zone electrophoresis (CZE) mode effected a separation of identically charged peptides; within each charged group of peptides, the addition of perfluorinated acid anionic ion-pairing reagents allowed resolution of the peptides through a mechanism based on peptide hydrophobicity which we have termed ioninteraction (II)-CZE. The peak capacity and peptide resolution of this CE approach was superior to that of RP-HPLC and stresses an important role for CE for peptide/proteomic applications.

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“…The sample plug was bracketed by a presample plug of water (0.5 psi65 s) and a postsample plug of buffer (0.5 psi615 s). The water plug implemented an on-line sample preconcentration mechanism [12] and the postsample plug (together with the voltage ramp [13]) prevented sample loss by thermal expansion of the sample plug. Phosphate buffers were prepared either by adjusting phosphoric acid to pH 2 with NaOH or by adjusting solutions of aq.…”

Section: Instrumentation and Conditionsmentioning

confidence: 99%

Capillary electrophoresis of amphipathic α‐helical peptide diastereomers

2004

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We have made a rigorous assessment of the ability of capillary electrophoresis to resolve peptide diastereomers through its application to the separation of a series of synthetic 18-residue, amphipathic alpha-helical monomeric peptide analogues, where a single site in the centre of the hydrophobic face of the alpha-helix is substituted by 19 L- or D-amino acids. Such L- and D-peptide pairs have the same mass-to-charge ratio, amino acid sequence and intrinsic hydrophobicity, varying only in the stereochemistry of one residue. CE approaches assessed in their ability to separate diastereomeric peptide pairs included capillary zone electrophoresis (uncoated capillary), micellar electrokinetic chromatography (uncoated capillary in the presence of 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate, CHAPS), open-tubular capillary electrochromatography (C(8)-coated capillary in the presence of 25% 2,2,2-trifluoroethanol (TFE) or 25% ethanol). Overall, the OT-CEC methods were the most effective at separating the most peptide pairs, particularly for those containing hydrophilic side chains. However, the MEKC approach proved most effective for separation of peptide pairs containing hydrophobic or aromatic side chains.

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Volume expansion and loss of sample due to initial self-heating in capillary electroseparation (CES) systems

Cited by 43 publications

References 2 publications

Joule heating effects on separation efficiency in capillary zone electrophoresis with an initial voltage ramp

Joule heating effects on separation efficiency in capillary zone electrophoresis with an initial voltage ramp

Capillary electrophoresis of cationic random coil peptide standards: Effect of anionic ion‐pairing reagents and comparison with reversed‐phase chromatography

Capillary electrophoresis of amphipathic α‐helical peptide diastereomers

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