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

Modes
CGE
t = 0
t > 0
Polymer matrix
Figure 41
Size-separation in CGE
hindered more than smaller ones. Macromolecules such
as DNA and SDS-saturated proteins cannot be separated
without a gel since they contain mass-to-charge ratios that
do not vary with size. That is, with DNA for example, each
additional nucleotide added to a DNA chain adds an equivalent
unit of mass and charge and does not affect the mobility
in free solution.
Capillary gel electrophoresis (CGE) is directly comparable
to traditional slab or tube gel electrophoresis since the
separation mechanisms are identical. The CE format can
offer a number of advantages over traditional slab gel
electrophoresis, including the use of 10 to 100 times higher
electric fields without the deleterious effects of Joule
heating (although ultra-thin slab gels have recently been
used to limit heating), on-capillary detection, and instrumental
automation. In addition, due to the anticonvective nature
of the capillary it is not necessary to use a gel that is itself
anticonvective. The capacity to run preparative separations,
considered a major advantage of the slab, can also
be accomplished to a certain extent in HPCE by the use of
wide-bore capillaries (internal diameters >100 to 200 mm)
and low electric fields. The multi-lane capacity of a slab,
however, is difficult to reproduce in capillary format,
although the rapid analysis times in CGE compensate.
Traditionally, crosslinked polyacrylamide and agarose have
been used in the slab or tube format. The former usually has
70