Selective laser detection modes in liquid chromatography

A fluorometric detection technique for liquid chromatography is described in Part I of this thesis. Fluorescence is monitored from a highly excited molecular state following sequential resonant excitation. Detection limits in the low nanogram range and linearity over three decades of concentration are demonstrated for the separation of several derivatized amines. Possible improvements in sensitivity and selectivity are also discussed.

The unique properties of the laser and the dependence of fluorescence signals on photon density for techniques excited by two pho-tons are shown to facilitate miniaturization of flow cells without loss in signal.

Part II of this thesis presents three different modes of laser fluorometric detection for thin-layer chromatography. Detection limits in the low to mid picogram range and linearity over approximately three decades of concentration are demonstrated for the separation of several derivatized amines and oxadiazole compounds. The sensitivity and selectivity of these techniques along with the unique properties of the laser should result in future applications of laser fluorimetry in thin-layer chromatography detection.