Principles of Electromigration Techniques
Electromigration techniques provide the separation of analyzed sample components owing to external voltage generating electrokinetic phenomena—electrophoresis and electroosmosis. Taking into account the relatively large number of parameters dealt with dur
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Principles of Electromigration Techniques Ewelina Dziubakiewicz and Bogusław Buszewski
Abstract Electromigration techniques provide the separation of analyzed sample components owing to external voltage generating electrokinetic phenomena— electrophoresis and electroosmosis. Taking into account the relatively large number of parameters dealt with during electrophoretic analyses, it is essential to know their influence on the achieved separation of analytes. In this chapter the theoretical and practical aspects of a resolution optimization, as well as the effect of different separation parameters on the migration behavior are described. These, among others, include migration time, efficiency, selectivity, and resolution. The influence of electrods polarization, applied voltage, temperature, capillary, background electrolyte, and various additives on the separation is also discussed. Electromigration techniques, due to their huge analytical potential, are widely applied in the determination of various substances. These techniques provide separation of components of an analyzed sample owing to external voltage generating electrokinetic phenomena—electrophoresis (motion of ions in an electrical field) and electroosmosis (volumetric liquid flow in a capillary caused by an electrical field). The separation takes place in a liquid phase in a solution called (acc. to various literature sources) a buffer, electrolyte or background electrolyte, separation buffer or separation electrolyte. It may be either an aqueous solution or based on pure organic solvents or their mixtures. Owing to their accuracy and precision of determination, they are widely applied in, e.g., the biochemistry of proteins and nucleic acids, molecular biology, pharmacology, forensic medicine, forensic science, medical diagnostics, and analysis of food E. Dziubakiewicz (&) B. Buszewski Faculty of Chemistry, Nicolaus Copernicus University, Torun´, Poland e-mail: [email protected] B. Buszewski e-mail: [email protected]
B. Buszewski et al. (eds.), Electromigration Techniques, Springer Series in Chemical Physics 105, DOI: 10.1007/978-3-642-35043-6_2, Springer-Verlag Berlin Heidelberg 2013
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E. Dziubakiewicz and B. Buszewski
Fig. 2.1 Types of electromigration techniques, according to [11, 20]
[1–10]. All electromigration techniques applied in laboratory practice are derivatives or combinations of three basic types of electrophoreses: Zone Electrophoresis, Isotachophoresis, and Isoelectric Focusing (Fig. 2.1).
2.1 Electrophoretic Mobility The electrophoretic separation stems from the difference in velocity of charged particles migrating under the influence of the electric field. In a capillary filled with a separation buffer, the ion is subject to two forces. One is an electrostatic force (F): (Fig. 2.2) F ¼ qE;
ð2:1Þ
where q is ions charge and E is strength of electric field [V cm-1], which is a function of the imposed voltage and length of the capillary. The second force is Fig. 2.2 Forces influencing an ion in separation buffer
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