Potential of Surface-Enhanced Raman Scattering Detector
for Capillary Electrophoresis
Mgr. Jan Přikryl
Consultant: Ing. Karel Klepárník, CSc.
Supervisor: doc. Mgr. Jan Preisler, Ph.D.
Surface-Enhanced Raman Spectroscopy (SERS) is interdisciplinary method covering
vibrational spectroscopy, plasmonics and nanotechnologies. This method is based on
the enhancement of the weak Raman scattering of molecules in a close proximity of
metal nanomaterials, such as metal nanoparticles, roughened surfaces or metal tips.
The enhancement factor could reach a value up to 1014
[1,2], and thus SERS becomes
a high sensitive analytical method. In most of the applications, SERS was used as a
stand-alone method. However, relatively little attention was focused to on-line
coupling of SERS with separation methods such as liquid chromatography or capillary
electrophoresis [3,4]. Nirode et. al. published a simple way to integrate the on-column
SERS detection in CE by usage of SERS-active silver nanoparticles suspended in the
background electrolyte [3]. Leopold et. al. prepared a spot of SERS substrate by laserinduced
citrate reduction of silver nitrate during the CE separation [4].
This presentation is devoted to a new, simple photodeposition method of silver
nanoparticles inside a fused-silica capillary induced by laser [5]. The photodeposited
compact spot of a size of ∼10 μm is temporary and spatially stable and resistant to a
hydrodynamic flow. The advantage of this approach is that neither the silver
nanoparticles nor the chemicals for their preparation are components of the
background electrolyte during the electrophoretic separation. Thus, the substrate
formation and separation of analytes are two independent processes and can be
performed under their optimum conditions. The zone broadening due to the sorption
of analytes on the immobilized nanoparticles can be significantly reduced by an
addition of 20% solution of methanol. The efficiency of capillary electrophoresis and
detection selectivity of surface-enhanced Raman scattering is demonstrated by the 3D
electropherograms of rhodamines 123 and B as model samples.
References
[1] Nie, S., Emory, S. R. Science 1997, 275, 1102-1106.
[2] Kneipp, K., Wang, Y., Kneipp, H., Perelman, L. T., Itzkan, I., Dasari, R. R., Feld,
M. S. Phys. Re . Lett. 1997, 78, 1667-1670.
[3] Nirode, W. F., Devault, G. L., Sepaniak, M. J., Anal. Chem. 2000, 72, 1866-1871.
[4] Leopold, N., Lendl, B., Anal. Bioanal.Chem. 2010, 396, 2341-2348.
[5] Přikryl, J., Klepárník, K., Foret, F., J. Chromatogr. A 2012, 1226, 43-47.