Biomedical Engineering – From Theory to Applications

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Biomedical Engineering – From Theory to Applications
instrumental arrangement and simultaneously (ii) to ensure the enhancement of the
compatibility within and reproducibility of the procedure. The column coupled non
electrophoretic stages include (i) chromatography (Pálmarsdóttir & Edholm, 1995;
Pálmarsdóttir et al., 1996, 1997), (ii) SPE extraction (Puig et al., 2007), (iii) dialysis (Lada &
Kennedy, 1997), and (vi) flow injection analysis (FIA) (Mardones et al., 1999). A great
potential of the hybrid on-line sample preparation techniques is given by their
complementarity that enables to cumulate positive effects and/or overcome the weak points
of the individual sample preparation techniques. In addition, these techniques, likevise to
CE-CE, can be simultaneously combined also with stacking effects or chemical reaction in
order to enhance further overall analytical effect as it is demonstrated in the following
sections. From the practical point of view, the following sections are starting with the on-line
implementation of FIA because the flow injection principles and instrumental
procedures/arrangements are widely applied also for the effective integration of other non
electrophoretic techniques (SPE, LC, dialysis) with CE.
3.1.2.1 FI-CE
The concept of flow injection analysis (FIA) was introduced in the mid-seventies. It was
preceded by the success of segmented flow analysis, mainly in clinical and environmental
analysis. This advance, as well as the development of continuous monitors for process
control and environmental monitors, ensured the success of the FIA methodology
(Trojanowicz et al., 2009; Lü et al., 2009). A combination of CE with a flow injection (FI)
offers a great scale of sample preparation and the most frequently it is used for the on-line
implementation of chemical reactions. The technique of combined flow injection CE (FI-CE)
integrates the essential favorable merits of FI and CE. It utilizes the various excellent on-line
sample pretreatments and preconcentration (such as cloud point extraction, SPE,
ionexchange, DPJ and head-column FESS technique, analyte derivatization) of FI, which has
the advantages of high speed, accuracy, precision and avoiding manual handling of sample
and reagents. Therefore, the coupling of FI-CE is an attractive technique; it can significantly
expand the application of CE and has achieved many publications since its first appearance
(Mikuš & Maráková, 2010).
Fig. 7. Typical FI manifold used for the derivatization of the analytes and their on-line
introduction into the CE system. Reprinted from ref. (Mardones et al., 1999), with
permission.
A high potential of the FI-CE method in automatization of sample derivatization and
subsequent separation was demonstrated by Mardones et al. (Mardones et al., 1999). The