Investigation of retention mechanism of resorcinarene based cavitands by linear and nonlinear chromatography

• Thermodynamics of the retention for cyclic oligomers were studied.
• Thermodynamic parameters were calculated by both linear and nonlinear chromatography.
• The adsorption isotherm of resorcinarenes and cavitands was determined by the inverse method.
• Error analysis of the results obtained with the inverse method was performed.

Cavitands are cavity-shaped cyclic oligomers and they can create host–guest interactions with various analytes, therefore they have applications in supramolecular chemistry, nanoscale reactions, chromatographic separations, drug encapsulation and delivery, biochemistry. The investigation of the chromatographic behavior of large molecules, such as resorcinarenes and cavitands is meager up to now. To understand the retention of resorcinarenes and cavitands in liquid chromatography, we studied their retention mechanism by the thermodynamic parameters calculated from the van’t Hoff equation and by generation of an adsorption isotherm, which can describe the adsorption of the solute on the stationary phase surface. We compared the thermodynamics of the retention for cyclic oligomers in acetonitrile:water and methanol:water mobile phases. Furthermore, we determined the equilibrium adsorption isotherm by inverse method and we made an error analysis of the estimation obtained with the inverse method to ascertain the validity of the obtained isotherm parameters over a broader concentration range.