Validated method for the determination of idazoxan in human plasma by liquid chromatography with tandem mass spectrometric detection

The effect of perchlorate anion as a mobile phase modifier on the retention of dansyl norvaline and dansyl tryptophan enantiomers on a human serum albumin (HSA) column was studied by varying the chaotropic agent concentrations. The thermodynamic parameters for the transfer of a solute from the mobile to the HSA stationary phases were determined from linear van't Hoff plots. An enthalpy-entropy compensation study revealed that the type of interaction between the solute and HSA was independent of the molecular structure. The parabolic variations observed with the enthalpic and entropic terms of dansyl amino acid transfer in relation to the concentration of perchlorate anion were considered to be the result of the change from reversed to normal-phase conditions for this chromatographic system.