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

Principles
rapidly eluting ions, the near-Gaussian peak shape of those
of moderate mobility, and the tailing of the low mobility, late
eluting ions.
Peak shape distortions are detrimental only if resolution
is lost. Measures to decrease these phenomena include
matching the mobilities of the buffer constituent to the
sample mobility or by maintaining a running buffer concentration
approximately two orders of magnitude higher than
that of the sample.
2.3.5 Resolution
Resolution of sample components is the ultimate goal in
separation science. Resolution is most simply defined as
2(t
R = 2
– t 1
) t
= 2
– t 1
(21)
w 1
+ w 2
4s
where t = migration time
w = baseline peak width (in time)
s = temporal standard deviation
subscripts 1 and 2 refer to the two
solutes.
The numerator in equation (21) describes the separation
process in terms of differential migration and the denominator
the dispersive processes acting against it.
Separation in CE is primarily driven by efficiency, not
selectivity. This is in contrast to chromatography in which
the opposite is usually true. Due to very sharp solute zones,
small differences in solute mobility (< 0.05 % in some cases)
are often sufficient for complete resolution. Of course, the
extent of dispersion is immaterial if sufficient mobility
differences are realized.
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