CE comprises several analytical methods with different separation mechanisms in which an applied electric field is used for the mobilization of the analytes.

Table 1: Summary of the electrophoretic separation mechanisms

Analysis method

Separation character



CZE (capillary zone electrophoresis)


Electrical field

Ionic bindings

CITP     (capillary isotachophoresis)


Electrical field

Ionic bindings

CGE (capillary gel electro- phoresis)

Molecule size

Gel structure, sieve effect

Higher molecular weight compounds

MEKC (micellar electrokinetic chromatography)

Interaction with the micelle and mobility

Distribution equilibrium, electric field

Neutral bindings

IEF (isoelectric focusing)

Isoelectric points


Ampholyte (e.g. proteins)

CEC (capillary electrochromatography)

Interaction with the stationary phase and movement by EOF

Distribution equilibrium, electric field

Ionic and neutral compounds (depending on the stationary phase)

The basic principles of the electrophoretic mechanisms have been known since the end of the 19th century.
The problem of the zone broadening due to thermic convection has been reduced through the application of stabilizing fillings such as cellulose, glass wool, and silica gel. Another way to avoid the thermic convection is through the use of tubes or capillaries which have a small internal diameter and which facilitate a fast removal of the Joule heating.

This so-called “Free Zone Electrophoresis” was first implemented by Tiselius and Hjerten in 1965 in rotating capillaries with 3 mm diameters and further developed by Hjerten in 1967. Since the end of the 1980s CE has gone through a rapid development and new separation mechanisms have been added (see table 1). In 1984 Terabe et al. used for the first time micellar components as electrolyte additives and thus enhanced the range of application of CE to include neutral compounds.

However, the method most frequently used for the electrophoretic separation of different analytes is still capillary zone electrophoresis, the field of application which ranges from inorganic ions to proteins to large biomolecules.

Source: Dissertation, Jana Boden, TU Darmstadt 1996, page 4.