HPLC-fluorescence detection and MEKC-LIF detection for the study of amino acids and catecholamines labelled with naphthalene-2,3-dicarboxyaldehyde.

Naphthalene-2,3-dicarboxyaldehyde (NDA) is commonly used for detection of primary amines in conjunction with their separation with HPLC and CE. The fluorescence of the derivatives can be measured by a conventional fluorometer or via LIF. NDA is a reactive dye, which can replace o-phthaldehyde (OPA) and provides for derivatives which are considerably more stable than OPA derivatives.

Analysis of tryptophan and tyrosine in cerebrospinal fluid by capillary electrophoresis and "ball lens" UV-pulsed laser-induced fluorescence detection.

For the purpose of this study, we used a "ball lens" UV laser-induced fluorescence (LIF) detector comprising a pulsed laser and a collinear optical arrangement. The fluorescence signal is induced by a pulsed laser and detected by a photomultiplier tube. When coupling the high-frequency pulsed laser to the LIF detector we used, the electronics which is designed for continuous wavelength (CW) lasers, "viewed" the laser as a continuous source.

Automated large-volume sample stacking procedure to detect labeled peptides at picomolar concentration using capillary electrophoresis and laser-induced fluorescence detection.

We have developed an automated large-volume sample stacking (LVSS) procedure to detect fluorescein isothiocyanate-labeled peptides in the picomolar range. The injection duration is 10 min at 50 mbar to fill 62% of the capillary volume to the detection cell. The calculated limit of detection (S/N=3), filling 1% of the capillary volume, is 74 pM for bradykinin and 45 pM for L-enkephalin with samples diluted in water and analyzed in a 50 mM borate buffer, pH 9.