Selectivity in fluorescence-based techniques is also much hight than in absorbance-based approaches. Unit several years ago, this was attributed primarily to the relatively low number of fluorescent species compared with absorbing ones the ability to employ both excitation and emission wavelengths as selectivity parameters. Recently, quite a few other selectivity parameters have been employed successfully; these multidimensional luminescence-based approaches have been reviewed recently (6). This multi dimensional nature of fluorescence-based techniques make fluorescence spectroscopy an ideal technique for bioanalytical studies.