Reliable electrophoretic mobilities free from joule heating effects using CE

Christopher Evenhuis, Vlastmil Hruska, Rosanne Guijt, Miroslav Macka, Bohuslav Gas, Philip Marriott, Paul Haddad

Research output: Contribution to journalArticleResearchpeer-review

19 Citations (Scopus)

Abstract

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.
Original languageEnglish
Pages (from-to)3759 - 3766
Number of pages8
JournalElectrophoresis
Volume28
Issue number20
DOIs
Publication statusPublished - 2007
Externally publishedYes

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