Biomedical Engineering – From Theory to Applications

Column Coupling Electrophoresis in Biomedical Analysis
column sample purification of the multicomponent and/or high salinity samples and (ii)
different separation mechanism applicable in the coupled channels (2D features).
Undoubtedly, a very reproducible transfer process, a well defined and highly efficient
removal of the matrix constituents from the separation compartment and the use of different
separation mechanisms in the channels are features that makes column switching ZE on the
CC chip a very promising tool for a miniaturized analysis of multicomponenet samples. The
ZE-ZE based MCE operating with a hydrodynamically closed separation system, makes a
separation platform for highly reproducible migrations of separated constituents
(Kaniansky et al., 2004; Sahlin, 2007; Hanna et al., 2000). The same instrumentation and
channel arrangement as used for ITP-ZE, ITP-ITP or ITP-GE can be also applied for ZE-ZE
(of course, with appropriate electrolyte systems).
3.2.2 Hyphenation of electrophoretic and non electrophoretic techniques
3.2.2.1 Extraction techniques
An interesting focus of research is the emergent development of microchips in the field of
the chip-based SPE–CE. However, the research in this field is mainly centered in the
manufacturing process, so the application of such microdevices is rather limited. In the
coming years research in this field will focus on exploring the potential of chip-based SPE–
CE for its application in the analysis of real samples (Puig et al., 2007, 2008). SPE is the most
attractive way of coupling extraction with CE and, especially, MCE, particularly as it can
provide significant improvements in sensitivity without the use of electrokinetic injection
(Puig et al., 2007, 2008; Bertoncini & Hennion, 2004).
A potential of the affinity extraction in a chip format for a comprehensive proteomic
analysis was demonstrated by Slentz (Slentz et al., 2003). This paper reports a system for
three-dimensional chip electrochromatography (for the scheme of the chip, see Fig.13). The
steps involved include (i) chemical reaction (enzymatic digestion), (ii) affinity extraction
(selection of e.g. histidine-containing peptides), and (iii) CEC separation (reversed-phase
capillary electrochromatography of the selected peptides). Fluidic manipulations including
loading media, sample injection, and sample elution can be successfully performed by
voltage manipulation alone.
Fig. 13. Scheme of the column used and SEM of the microfabricated frit (frit B) and head of
the collocated monolithic support structure (COMOSS) column. Reprinted from ref. (Slentz
et al., 2003), with permission.
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