An HPLC chromatographic framework to analyze the beta-cyclodextrin/solute complexation mechanism using a carbon nanotube stationary phase

A carbon nanotube (CNT) stationary phase was used for the first time to study the beta-cyclodextrin (beta-CD) solute complexation mechanism using high performance liquid chromatography (HPLC). For this, the beta-CD was added at various concentrations in the mobile phase and the effect of column temperature was studied on both the retention of a series of aniline and benzoic acid derivatives with the CNT stationary phase and their complexation mechanism with beta-CD. A decrease in the solute retention factor was observed for all the studied molecules without change in the retention order. The apparent formation constant K-F of the inclusion complex beta-CD/solute was determined at various temperatures. Our results showed that the interaction of beta-CD with both the mobile phase and the stationary phase interfered in the complex formation. The enthalpy and entropy of the complex formation (Delta H-F and Delta S-F) between the solute molecule and CD were determined using a thermodynamic approach. Negative enthalpies and entropies indicated that the inclusion process of the studied molecule in the CD cavity was enthalpically driven and that the hydrogen bonds between carboxylic or aniline groups and the functional groups on the beta-CD rim play an important role in the complex formation. (C) 2015 Elsevier B.V. All rights reserved.