Sensitive detection and separation of fluorescent derivatives using capillary electrophoresis with laser-induced fluorescence detection with 532 nm Nd:YAG laser - Analytical Methods & Tools for Lyophilization

Sensitive detection and separation of fluorescent derivatives using capillary electrophoresis with laser-induced fluorescence detection with 532 nm Nd:YAG laser
Received 23 December 2004. Available online 28 December 2005.
Patrik Vr?bel, Petr T?borsk?, Mark?ta Ryvolov?, Josef Havel and Jan Preisler
Journal of Luminescence
Volume 118, Issue 2 , June 2006
ScienceDirect
Department of Analytical Chemistry, Faculty of Science, Masaryk University, Kotl?rsk? 2, 611 37 Brno, Czech Republic
Abstract
Capillary electrophoresis with laser-induced fluorescence detection (CELIF) is a powerful tool for separation and sensitive determination of fluorescent species. Biologically active compounds, such as amino acids, peptides and proteins may exhibit native fluorescence, which is however often low and/or an expensive laser is required for excitation in UV. Therefore, labelling of the analytes with a fluorescent dye is usually necessary.
In this work, a home-built CELIF instrument with diode pumped frequency-doubled continuous wave Nd:YAG excitation laser with feedback power regulation (532 nm) was constructed. The suitability of this type of laser for LIF detection in a separation method was found excellent. A limit of detection (LOD) (S/N=3) of 2?10-13 mol/l was achieved with rhodamine B, which is comparable to those obtained using similar instruments with Ar+ laser [Y.F. Cheng, N.J. Dovichi, Science 242 (1988) 562, E.S. Yeung et al., J. Chromatogr. 608 (1992) 73]. LOD of a protein derivatized according to modified procedures [M.J. Little et al., Anal. Chim. Acta 339 (1997) 279, A. Chersi et al., Biochim. Biophys. Acta 1336 (1997) 83] was determined. Detection of the derivatives was found to be limited by insufficient reaction recovery at low analyte concentration, chemical noise, separation efficiency and quality of the derivatizing reagent rather than by the detector performance. As a consequence, a huge gap between the detection ability of CELIF instruments and LOD determined in real samples is revealed.
Keywords: Capillary electrophoresis; Fluorescence; Derivatization; Proteins; Rhodamine; 532 nm Laser
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