Study of the chromatographic behavior and inclusion constants of new fluorescence agents by use of cyclodextrin additives under conditions of steady-and dynamic-state equilibrium and with fluorescence detection

We report four new derivatization agents, acridone-N-acetic acid (ARC), car bazole-9-ylacetic acid (CRA), carbazole-9-ylpropionic acid (CRP), and 2-met hyl-2-carbazole-9-ylacetic acid (MCRA), with strong fluorescence emission w hich has low dependence on solvent polarity. The emission maxima for ARC, C RA, CRP, and MCRA were 430 nm (lambda(ex) 404 nm), 368 nm (lambda(ex) 335 n m), 356 nm (lambda(ex) 340 nm) and 360 nm (lambda(ex) 330 nm), respectively . The effects of mobile-phase composition, DH, and temperature on the liqui d chromatographic retention behavior of the four fluorescence agents were i nvestigated. An experimental model was established for calculating the incl usion constants of cyclodextrin (CD) complexes in the dynamic state, using beta-cyclodextrin (beta-CD) and hydroxypropyl-beta-cyclodextrin (HP-beta-CD ) as examples, and different mobile-phase compositions. On the basis of the model, the inclusion constants of the solutes in pure water (K-fw) were de termined by extrapolation. The thermodynamic parameters (Delta H degrees an d Delta S degrees) and dissociation constants K-am for the solutes in this chromatographic system were obtained by weans of capacity factor (k) values using a corresponding model formulation.