FLUORESCENCE CHARACTERIZATION OF ACID-BASE INTERACTION AND MOBILITY AT CHROMATOGRAPHIC INTERFACES

Chromatographic surfaces are investigated by means of fluorescent prob es (aza-aromatic compounds and anthroic acids). From absorption and fl uorescence spectra the acid-base equilibria and types of binding at th e interfaces are determined. The different surface acidities are given in terms of pH equivalents, which cover a range of more than three De lta pH units. The rotational mobility of probe molecules on reversed p hase materials is measured to get a more detailed understanding of the chromatographic separation mechanism. The rotational correlation time is calculated from fluorescence anisotropy and decay time measurement s.