Department of Analytical Chemistry, Jagiellonian University in Kraków, Faculty of Chemistry , Ingardena St. 3, 30-060 Kraków, Poland.
Anal Chem. 2017 Mar 21;89(6):3630-3638. doi: 10.1021/acs.analchem.6b05036. Epub 2017 Feb 28.
Electrophoretic mobility is a basic parameter that describes the electromigration of an ionized particle, which is used in many fields of analytical and physicochemical science. Its determination by capillary electrophoresis (CE), using a routine method, is intrinsically affected by the generation of Joule heating, entailing a drop in viscosity and possible alteration of the degree of ionization, and also by other commonly overlooked effects: axial electric field distortion and voltage ramping. The objective of this work was to provide the first theoretical overview and experimental comparison of all accessible methods that could be used to prevent these sources of inaccuracy. We have discussed seven independent approaches: (i) extrapolation of mobility to the zero power, (ii) initial buffer resistance-based correction, (iii) rational cooling adjustment, (iv) elimination of the nonthermostated capillary part, (v) inter/extrapolation to the nominal temperature, (vi) internal standard-based correction, and (vii) simple recalculation based on the temperature rise. Two methodologies (v and vi) have been proposed for the first time. Furthermore, we have shown how some approaches can be further developed, obtaining several novel and more sophisticated methods, which are also included in the comparison. Our investigation will help researchers to choose the optimal approach. We have also demonstrated for the first time how to measure the independent impact of four different effects. The outcomes reveal the compensatory character of some phenomena and explain the highly diverse and unpredictable magnitude of the total errors. The use of a correction method seems crucial for ensuring the high reliability of CE-based analyses.
电泳淌度是描述离子化颗粒电迁移的基本参数，在分析化学和物理化学科学的许多领域都有应用。采用常规方法，通过毛细管电泳（CE）对其进行测定会受到焦耳加热的影响，导致粘度下降和可能改变电离度，还会受到其他通常被忽视的影响：轴向电场变形和电压斜坡。本工作的目的是首次提供理论概述和实验比较，可用于防止这些误差源的所有可用方法。我们讨论了七种独立的方法：（i）将淌度外推至零功率，（ii）基于初始缓冲液电阻的校正，（iii）合理的冷却调节，（iv）消除非恒温毛细管部分，（v）插值/外推至标称温度，（vi）基于内部标准的校正，以及（vii）基于温升的简单重新计算。其中方法（v）和（vi）是首次提出的。此外，我们还展示了如何进一步开发某些方法，获得了几种新颖而复杂的方法，这些方法也包括在比较中。我们的研究将有助于研究人员选择最佳方法。我们还首次展示了如何测量四种不同效应的独立影响。结果揭示了一些现象的补偿性，并解释了总误差的高度多样化和不可预测的幅度。使用校正方法对于确保 CE 分析的高可靠性似乎至关重要。
