Biomedical Engineering – From Theory to Applications

Column Coupling Electrophoresis in Biomedical Analysis
one or more cuttings depending on the zones of interest and/or interfering matrix
constituents present in the sample. The interface between the separation solutions in the ITP
and CZE capillary is free (without any mechanical restraint) but mixing of the electrolytes is
eliminated (with the exception of difusion) by suppressing all non selective flows
(hydrodynamic, electroosmotic) in the system. This is advantageous by an easy construction
and elimination of dead volumes in the separation system (Ölvecká et al., 2001; Kaniansky et
al., 2003).
Fig. 2. ITP sample clean up for CZE with the closed separation system (without any
supporting non selective flow). (a) Starting arrangement of the solutions in the capillaries;
(b) ITP separation with the analyte (A) trapped into the boundary layer between the zones
of front (M1) and rear (M2) spacers; (c) end of the run in the ITP capillary followed by an
electrophoretic transfer of the analyte containing fraction to the CZE capillary (by switching
the direction of the driving current); (d) removal of the sample constituents migrating
behind the transferred fraction (by switching the direction of the driving current); (e)
starting situation in the separation performed in the CZE capillary (the direction of the
driving current was switched); (f) separation and detection of the transferred constituents in
the CZE capillary. BF = bifurcation region; C1, C2 = the ITP and CZE separation capillaries,
respectively; D-ITP, D-ZE = detection sensors in the ITP and CZE separation capillaries,
respectively; TES = terminating electrolyte adapted to the composition of the sample (S);
TITP = terminating electrolyte adapted to the composition of the leading electrolyte
solution; A = analyte, i = direction of the driving current. Reprinted from ref. (Kaniansky et
al., 2003), with permission.
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