Fluorescence detection in capillary electrophoresis using a variable wavelength epi-fluorescence microscope

Abstract

A capillary electrophoresis fluorescence detector is described. A high-pressure mercury lamp with a filter block allowed the selection of a particular excitation waveband. Detection was performed on-column, the fluorescence emission was monitored and measured with a silicon photodiode detector with a built-in amplifier. The concentration limit of detection (CLOD) of 0.4 ng/mL was obtained for rhodamine B, a fluorescent indicator. Based on an estimated injection volume of 2.5 nL, the mass limit of detection (MLOD) was 2.1×10-18 mol. The separation of three fluorescent indicators: thionine, eosin yellowish and rhodamine B, was achieved in less than 6 min. The separation of nine porphyrin-free acids using the system developed was also demonstrated. The advantages and potential of using an epi-illumination microscope as a versatile and sensitive fluorescence detection system for capillary electrophoresis are described. © 1994 Springer-Verlag.