Fluorescence detection in capillary electrophoresis: Detector cell

A newly developed fluorescence detector cell for capillary electrophoresis was described. Detection of analytes having fluorescence is performed in an on-capillary mode with a xenon are lamp. A grating monochromator was used for the selection of the excitation wavelength. Fluorescence emission was m onitored by collection of light from the capillary using a newly devised de tector cell positioned at right angle to the excitation beam. Emission wave lengths were isolated using a filter and amplified with a photomultiplier. The detection limits obtained using the newly devised detector cell for ami no acids and carbohydrates labeled with a fluorescent reagent were compared with that obtained using a conventional quartz detector cell. The results indicated that 100 nM and 4 mu M of amino acids and oligosaccharides labele d with 9-fluorenymethyl chloro- formate and 2-aminopyridine, respectively, could be detected with the newly devised detector cell, in contrast to no s ignals with the conventional quartz detector cell. The separation and detec tion of fluorescent derivatives of amino acids, peptides, monosaccharides a nd oligosaccharides were also performed and an appropriate linearity was ob served in a detector response of the samples within the constant concentrat ion.