Electrophoretic method for the determination of diffusion coefficients of ions in aqueous solutions*

Bozhikov, G. A.; Bontchev, G. D.; Ivanov, P.; Priemyshev, A. N.; Maslov, O. D.; Milanov, M.; Dmitriev, S. N.

doi:10.1023/b:jrnc.0000011763.86648.b5

Cited by 5 publications

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“…Both theoretically and practically, it is also important that electrophoretic mobility of a charged species is directly associated with its limiting equivalent conductivity (l i,z ) and its diffusion coefficient (D i,z ) [2,3]. Therefore, the ability to determine the limiting ionic mobilities accurately is essential.…”

Section: Introductionmentioning

confidence: 99%

“…There have been two major approaches to determining limiting electrophoretic mobilities of ions, (i) based on measurements of conductivity [2,3] and (ii) electrophoretic methods [4]. The first approach uses the relationship between the limiting molar ionic conductivity, l In practice, measurements of conductivity are made over a range of concentrations, and extrapolation to zero concentration is used to find the limiting molar conductivity.…”

Section: Introductionmentioning

confidence: 99%

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Reliable electrophoretic mobilities free from Joule heating effects using CE

et al. 2007

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Ionic electrophoretic mobilities determined by means of CE experiments are sometimes different when compared to generally accepted values based on limiting ionic conductance measurements. While the effect of ionic strength on electrophoretic mobility has been long understood, the increase in the mobility that results from Joule heating (the resistive heating that occurs when a current passes through an electrolyte) has been largely overlooked. In this work, a simple method for obtaining reliable and reproducible values of electrophoretic mobility is described. The electrophoretic mobility is measured over a range of driving powers and the extrapolation to zero power dissipation is employed to eliminate the effect of Joule heating. These extrapolated values of electrophoretic mobility can then be used to calculate limiting ionic mobilities by making a correction for ionic strength; this somewhat complicated calculation is conveniently performed by using the freeware program PeakMaster 5. These straightforward procedures improve the agreement between experimentally determined and literature values of limiting ionic mobility by at least one order of magnitude. Using Tris-chromate BGE with a value of conductivity 0.34 S/m and ionic strength 59 mM at a modest dissipated power per unit length of 2.0 W/m, values of mobility for inorganic anions were increased by an average of 12.6% relative to their values free from the effects of Joule heating. These increases were accompanied by a reduction in mobilities due to the ionic strength effect, which was 11% for univalent and 28% for divalent inorganic ions compared to their limiting ionic mobilities. Additionally, it was possible to determine the limiting ionic mobility for a number of aromatic anions by using PeakMaster 5 to perform an ionic strength correction. A major significance of this work is in being able to use CE to obtain reliable and accurate values of electrophoretic mobilities with all its benefits, including understanding and interpretation of physicochemical phenomena and the ability to model and simulate such phenomena accurately.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%