Capillary electrophoresis with laser induced fluorescence as a useful tool for biomarker
                                        analysis[DEL: :DEL]

                      Júlia Lačná^1,2, František Foret^1,3, Petr Kubáň^1,2,3


^1 Department of Bioanalytical instrumentation, CEITEC MU, Veveří 97, 602 00 Brno, Czech Republic

^2 Department of Chemistry, Masaryk University, Kotlářská 2, 611 37 Brno, Czech Republic,

^3 Department of Bioanalytical Instrumentation, Institute of Analytical Chemistry, Czech Academy of
Sciences, v.v.i., Veveří 97, 602 00, Brno, Czech Republic


For accurate and reliable clinical diagnosis, suitable analytical methods for the determination of
biological markers are necessary. Non-invasive samples, such as exhaled breath condensate (EBC),
are more comfortable for patients, but more challenging for the analysts due to low sample volumes
and low concentrations of biomarkers. Sensitive analytical methods are required. Capillary
electrophoresis (CE) with laser induced fluorescence (LIF) detection can increase the detection
sensitivity to nM levels and improve selectivity.

Sensitive CE methods with LIF detection for the determination of malondialdehyde (MDA) and
glutathione (GSH) in various biological fluids were developed. The developed methods offer
unprecedented detection sensitivity, as low as 1nM. The methods proved to be applicable not only to
EBC but also to other biological fluids, such as blood plasma and saliva. Presented electrophoretic
methods were for the first time used in the determination of glutathione and malondialdehyde in
EBC. [1,2]

Highly efficient separations, short analysis times, and small sample consumption are the main
assets of the CE-LIF technique, especially for the analysis of non-invasive samples. In combination
with another strong detection method as contactless conductivity (C4D) – CE‑C4D–LIF provided an
efficient separation and quantitation of ionic content and GSH at concentrations differing by more
than three orders of magnitude in a single run. We have optimized the composition of background
electrolyte for the simultaneous analysis of biologically important ions using dual C4D–LIF
detection. Sensitive detection of anions, cations, and organic acids with micromolar LODs using C4D
and simultaneously glutathione with nanomolar LODs using LIF was achieved in a single run. The
developed electrolyte may be useful in analyses of biological samples containing analytes with
differing concentrations of several orders of magnitude that is not possible with a single
detection mode. [3]

CE-C4D technique was also used in another long-term project, aimed at biomarker analysis for
diagnosis of gastroesophageal reflux disease (GERD). Up to 20-40% of the population in the western
world suffers from GERD with typical symptoms including heartburn and regurgitation. The aim of
this study was to compare the composition of EBC in a group of patients with proven GERD and a
group of healthy controls. The ionic profile of EBC samples (anions, cations, organic acids) was
also measured by CE-C4D and several compounds were identified as potential markers that could be
used to distinguish the GERD patients and healthy controls. The developed approach can provide a
fast and non-invasive preselection of patients with reflux. [4]


 [1]    Hodakova, J., Preisler, J., Foret, F., Kuban, P., Sensitive determination of glutathione in
biological samples by capillary electrophoresis with green (515 nm) laser induced fluorescence
detection, Journal of Chromatography A 2015, 1391, 102–108.

[2]     Lacna, J., Foret, F., Kuban, P., Sensitive determination of malondialdehyde in exhaled
breath condensate and biological fluids by capillary electrophoresis with laser induced
fluorescence detection, Talanta 2017, 169, 85–90.

[3]     Lacna, J., Prikryl, J., Teshima, N., Murakami, H., Esaka, Y., Foret, F., Kuban, P.,
Optimization of background electrolyte composition for simultaneous contactless conductivity and
fluorescence detection in capillary electrophoresis of biological samples, Electrophoresis 2019,
40, 18-19.

[4]     Lacna, J., Durc, P., Gregus, M., Skrickova, J., Doubkova, M., Pokojova, E., Kindlova, D.,
Dolina, J., Konecny, S., Foret, F., Kuban, P., Capillary electrophoretic analysis of ionic content
in exhaled breath condensate and pH monitoring as a non-invasive method in gastroesophageal reflux
disease diagnostics, Journal of Chromatography B 2019, 1134, 1-7.