Institut des Biomolécules Max Mousseron, UMR 5247 CNRS, Université de Montpellier 1, place Eugène Bataillon CC 1706, 34095 Montpellier Cedex 5, France.
Anal Chem. 2012 Nov 6;84(21):9422-30. doi: 10.1021/ac302033z. Epub 2012 Oct 10.
The effective mobility (μ(ep)) is the main parameter characterizing the electrophoretic behavior of a given solute. It is well-known that μ(ep) is a decreasing function of the ionic strength for all solutes. Nevertheless, the decrease depends strongly on the nature of the solute (small ions, polyelectrolyte, nanoparticles). Different electrophoretic models from the literature can describe this ionic strength dependence. However, the complexity of the ionic strength dependence with the solute characteristics and the variety of analytical expressions of the different existing models make the phenomenological ionic strength dependence difficult to comprehend. In this work, the ionic strength dependence of the effective mobility was systematically investigated on a set of different solutes [small mono- and multicharged ions, polyelectrolytes, and organic/inorganic (nano)particles]. The phenomenological decrease of electrophoretic mobility with ionic strength was experimentally described by calculating the relative electrophoretic mobility decrease per ionic strength decade (S) in the range of 0.005-0.1 M ionic strength. Interestingly, the "slope plot" displaying S as a function of the solute electrophoretic mobility at 5 mM ionic strength allows for defining different zones that are characteristic of the solute nature. This new representative approach should greatly help experimentalists to better understand the ionic strength dependence of analyte and may contribute to the characterization of unknown analytes via their ionic strength dependence of electrophoretic mobility.
有效迁移率（μ(ep)）是描述给定溶质电泳行为的主要参数。众所周知，对于所有溶质，μ(ep)都是离子强度的递减函数。然而，这种下降强烈依赖于溶质的性质（小离子、聚电解质、纳米颗粒）。文献中有不同的电泳模型可以描述这种离子强度依赖性。然而，由于溶质特性和不同现有模型的分析表达式的多样性，使得离子强度依赖性的复杂性难以理解。在这项工作中，我们系统地研究了一系列不同溶质[小单电荷和多电荷离子、聚电解质和有机/无机（纳米）颗粒]的有效迁移率的离子强度依赖性。通过计算每 10 个离子强度单位（S）的相对电泳迁移率下降值（S），在 0.005-0.1 M 离子强度范围内实验描述了电泳迁移率随离子强度的经验下降。有趣的是，以 5 mM 离子强度下溶质电泳迁移率为函数的“S 斜率图”可以定义不同的区域，这些区域是溶质性质的特征。这种新的代表性方法应该可以极大地帮助实验人员更好地理解分析物的离子强度依赖性，并有助于通过其电泳迁移率的离子强度依赖性来表征未知分析物。
