The fluorescence spectra of 8-anilino-1-naphthalene sulfonic acid (ANS) and 7-toluidino-2-naphthalene sulfonic acid (TNS) were observed with or without various cyclodextrins. From the change of fluorescence intensity, the association constants between cyclodextrins and fluorescent probes (K) and the fluorescence intensity constants (i_0) for each cyclodextrin complex were calculated. The value of i_0 depended on the probe\u27s local microenvironment. These parameters assist in explication of the complex formation. And the effect of methylation of cvclodextrin for inclusion behavior is also indicated
