Study of the Mechanism of Enantioseparation. VII. Effect of Temperature on Retention of Some Enantiomers of Phenylcarbamic Acid Derivates on a Teicoplanin Aglycone Chiral Stationary Phase

Abstract

It has been found that the teicoplanin aglycone (CHIROBIOTIC TAG) chiral stationary phase is a useful column for the high performance liquid chromatographic (HPLC) separation of enantiomers of 1‐methyl‐2‐piperidinoethylesters of 2‐, 3‐ and 4‐alkoxy‐phenylcarbamic acid (potential local anaesthetic drugs) in the polar organic mode. The enantiomers were separated on a CHIROBIOTIC TAG column, isothermally in the range of 0–50°C with 10°C increments, using methanol [100 mL (v)] containing 17.5 mmol L⁻¹ acetic acid and 4.8 mmol L⁻¹ diethylamine as a mobile phase. van't Hoff plots (dependence of ln k _i on 1/T, where k is the retention factor of a solute i and T is the temperature) were linear in the studied temperature interval. This allowed the determination of interaction enthalpies (ΔH _i ), entropy (ΔS _i ), and Gibbs energies (ΔG _i ). This thermodynamic information was used to evaluate the retention and resolution of enantiomers of studied analytes in this HPLC system.

Keywords:

• Enantiomeric separation
• HPLC
• CHIROBIOTIC TAG
• Thermodynamic study
• Enthalpy–entropy compensation
• Local anaesthetic drugs
• Alkoxysubstituted esters of phenylcarbamic acid

Acknowledgments

Authors acknowledge the support of the Grant Agency of Slovak Republic (VEGA 1/8213/01 and 1/9127/02) and the Agency for International Science and Technology Cooperation in Slovakia (Grant No. 035/2001, USA‐SK).