Conductance of electrolytes in ethanol solutions from ?45 to 25�C

Barthel, J.; Neueder, Roland; Feuerlein, F.; Strasser, F.; Iberl, L.

doi:10.1007/bf00651698

Cited by 41 publications

(21 citation statements)

References 25 publications

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“…It should be noted, however, that incomplete ionization of sodium acetate will affect the pH of the BGE. Even though, to our knowledge, no data for the association constants of this salt in EtOH are available, some data are reported for simple 1-1 salts [29]. According to this data, association constants vary from , 30-200 L/mol.…”

Section: Approximation Of Dissosiation Degree and K Emdmentioning

confidence: 85%

Peak dispersion and contributions to plate height in nonaqueous capillary electrophoresis at high electric field strengths: Ethanol as background electrolyte solvent

Palonen¹,

Jussila²,

Porras³

et al. 2004

Electrophoresis

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Nonaqueous capillary electrophoretic separations were performed under high electric field strengths (up to 2000 Vcm(-1)) in ethanolic background electrolyte solution and the contributions of different band broadening effects to plate height were evaluated. Under optimum conditions, increasing the field strength will provide faster separations and increased separation efficiency. Decrease in the separation efficiency at high field strengths was, however, observed in a previous study and now in the present paper an attempt is made to quantify various band broadening effects by applying a plate height model, which included the contributions of the injection plug length, diffusion, electromigration dispersion, Joule heating, analyte adsorption to the capillary wall, and detector slit aperture length. Of special interest were the contributions of Joule heating and analyte adsorption to the capillary wall. Poly(glycidylmethacrylate-co-N-vinylpyrrolidone)-coated fused-silica capillaries were used with internal diameters (ID) ranging from 30 to 75 microm. The separation efficiencies obtained experimentally were compared with the theoretically calculated efficiencies and fairly good agreement was observed for the 30 microm ID capillary. Relatively large deviation from the predictions of the model was found for the other capillary diameters especially at higher field strengths. The possible reasons for the deviation were discussed.

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Section: Approximation Of Dissosiation Degree and K Emdmentioning

confidence: 85%

Peak dispersion and contributions to plate height in nonaqueous capillary electrophoresis at high electric field strengths: Ethanol as background electrolyte solvent

Palonen¹,

Jussila²,

Porras³

et al. 2004

Electrophoresis

View full text Add to dashboard Cite

show abstract

“…In these investigations, the BGEs were prepared from acetic acid and its salt in equimolar proportion. Due to strong ion pairing in solvents with such low relative permittivity (for ionic association in ethanol and 1-propanol, see [78,79], respectively), salts are only partly dissociated, which means that the pH of equimolar acetic acid and acetate BGEs is lower than the theoretical value. Accordingly, it is clear that the Henderson-Hasselbalch equation cannot appropriately be applied for pH adjustments in such solvents.…”

Section: Other Solventsmentioning

confidence: 97%

Capillary zone electrophoresis in non-aqueous solutions: pH of the background electrolyte

Porras

Kenndler

2004

Journal of Chromatography A

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“…For solvents with high dielectric constant and for low electrolyte concentrations the Fuoss-Onsager equation approaches the Onsager limiting law. Barthel et al [57][58][59][60] …”

Section: From Theory Of Ion Conductance In Solutionmentioning

confidence: 98%

Theoretical and empirical approaches to express the mobility of small ions in capillary electrophoresis

Jouyban

Kenndler

2006

Electrophoresis

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A discussion is given about the concepts of the ion mobility, the analyte property which governs migration and thus separation selectivity in CE. It deals with small organic and inorganic ions, not with charged polymers or large particles like colloids. The discussion is directed to two main concepts. (i) The first is based on physico-chemistry of ion conductance in solution, and distinguishes three types of mobility. The absolute mobility is the limiting mobility at zero ionic strength; it depends on the solvent and the temperature. It is obtained by extrapolation of the actual mobilities, those of the fully charged particles at finite ion concentration. The observed reduction of the absolute mobility with ionic concentration is related to an ion cloud, and is formulated by the established theories of ion conductance. It explains the actual mobility as function of (beside other factors) the ionic strength, the viscosity and relative permittivity of the solvent, the temperature, the relaxation time of solvent polarisation and the distance of closest approach between ion and counterion. The effective mobility, finally, is the mobility when association and dissociation equilibria play a role. Most important are acid-base reactions, but complexation, ion pairing and homo- and heteroconjugation were considered as well. (ii) The second approach treats mobility data with different mathematical methods, and formulates their dependence on variables like solvent composition with appropriate algorithms. These empirical methods mainly include least squares and neural network-based methods. The least square methods ranges from the simplest model, which uses only the molecular weight of the analyte, to more complicated model requiring three-dimensional structural descriptors of the solutes. Neural networks have been applied to model the mobility using different input variables and various architectures. Work comparing the accuracy of least squares and neural network methods was discussed; the results showed that the neural network method leads to a more accurate mobility calculation. However, the least squares methods could give some information to the factors affecting the mobility of the analytes. The resulting methods allow the prediction of mobilities under different experimental conditions with certain accuracy. It has been shown that using such models, it is possible to predict mobility of analytes after training the models by a minimum number of data to speed up the method development stage.

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Conductance of electrolytes in ethanol solutions from ?45 to 25�C

Cited by 41 publications

References 25 publications

Peak dispersion and contributions to plate height in nonaqueous capillary electrophoresis at high electric field strengths: Ethanol as background electrolyte solvent

Peak dispersion and contributions to plate height in nonaqueous capillary electrophoresis at high electric field strengths: Ethanol as background electrolyte solvent

Capillary zone electrophoresis in non-aqueous solutions: pH of the background electrolyte

Theoretical and empirical approaches to express the mobility of small ions in capillary electrophoresis

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