High performance capillary electrophoresis - T.E.A.M.

Modes
3.1 Capillary zone
electrophoresis
Capillary zone electrophoresis (CZE) is the most widely
used mode due to its simplicity of operation and its versatility.
The application range of CZE is diverse. Application
areas include the analysis of amino acids, peptides, ions, a
wide range of enantiomers, and numerous other ionic
species. In the area of protein analysis it has been used for
purity validation, screening protein variants, and conformational
studies, for example.
CZE is fundamentally the simplest form of CE, mainly
because the capillary is only filled with buffer. As shown in
figure 8 and 21a, separation occurs because solutes migrate
in discrete zones and at different velocities. Separation of
both anionic and cationic solutes is possible by CZE due to
electro-osmotic flow (EOF). Neutral solutes do not migrate
and all coelute with the EOF.
The name CZE is somewhat confusing in that it implies that
it is the only mode in which “zonal” electrophoresis occurs.
However, MEKC and CGE are also zonal techniques. In
contrast, CIEF is defined as a “focusing” technique and ITP
as a “moving boundary” technique. More suitable names for
CZE might be open-tube or free-solution electrophoresis.
Despite the ambiguity, the term CZE will be used here to
maintain consistent nomenclature with most published
literature.
Many of the theoretical aspects of CZE have been considered
in section 2.3. The following sections discuss methods
of altering selectivity, the use of additives, and describe
coatings that alter the charge and hydrophobicity of the
capillary wall.
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