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On the ionic strength dependence of the electrophoretic mobility: From 2D to 3D slope‐plots
Author(s) -
Cottet Hervé,
Wu Hengfu,
Allison Stuart A.
Publication year - 2017
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/elps.201600329
Subject(s) - electrophoresis , ionic strength , chemical physics , ion , ionic bonding , chemistry , polyelectrolyte , effective nuclear charge , hydrodynamic radius , ionic potential , electrolyte , charge density , debye length , radius , charge (physics) , work (physics) , analytical chemistry (journal) , materials science , nanoparticle , thermodynamics , chromatography , aqueous solution , nanotechnology , physics , polymer , dynamic light scattering , organic chemistry , computer science , computer security , electrode , quantum mechanics
Determining the charge and the nature (small ion, nanoparticle, or polyelectrolyte) of an unknown solute from its electrophoretic characteristics remains a challenging issue. In this work, we demonstrate that, if the knowledge of the effective electrophoretic mobility (μ ep ) at a given ionic strength is not sufficient to characterize a given solute, the combination of this parameter with ( i ) the relative decrease of the electrophoretic mobility with the ionic strength ( S ), and ( ii ) the hydrodynamic radius ( R h ), is sufficient (in most cases) to deduce the nature of the solute and its charge. These three parameters are experimentally accessible by CZE and Taylor dispersion analysis performed on the same instrumentation. 3D representation of the three aforementioned parameters (μ ep ; S and R h ) is proposed to visualize the differences in the electrophoretic behavior between solutes according to their charge and nature. Surprisingly, such 3D slope plot in the case of small ions and nanoparticles looks like a “whale‐tail,” while polyelectrolyte contour plot represents a rather simple and monotonous map that is independent of solute size. This work also sets how to estimate the effective charge of a solute from a given experimental ( S , R h , μ ep5 mM) triplet, which is not possible to obtain unambiguously with only ( R h , μ ep5 mM) or ( S , μ ep5 mM) doublet, where μ ep5 mMis the effective electrophoretic mobility at 5 mM ionic strength.