4.5.3 Laser-Induced Fluorescence (LIF)

Laser-induced fluorescence adapts fluorescence spectrometry to CE in the same manner as UV-vis spectrometry. A laser is used to excite the analyte, and fluorescence is measured via a PMT. Often the laser is aligned non-collinearly, and a ball lense is used to focus the light on the center of the capillary. Generally, a reflective ellipsoid is glued to the capillary to direct fluorescence toward the PMT.

A drawback of LIF is that most compounds of interest in CE are not fluorescent. However, a number of derivatizing agents can be used to act as markers for the compound. These are generally organic aromatics and require excitation between 250nm and 500nm.