Capillary Electrophoretic Chiral Separation of Antihistamines: Enantiomers Recognition Mechanism by Isothermal Titration Calorimetry and Simulation Studies

ABSTRACT The chiral separation of chlorpheniramine, brompheniramine, and dimetindene antihistamines was achieved by capillary electrophoresis using β‐CD, DM‐β‐CD, and TM‐β‐CD in 50 mM phosphate buffer (pH 3.0), with an applied voltage of 20 kV, a temperature of 20°C, and UV detection at 220 nm. The migration times of the enantiomers were in the ranges 7.31–28.10, 14.10–17.02, and 7.30–16.19 min for the three cyclodextrins, respectively. The number of theoretical plates varied between 6588–14,038, 9744–45,780, and 41,983–107,846. The separation factors (α) were 1.01–1.02, 1.03–1.04, and 1.02–1.03, while the resolution factors (Rₛ) ranged from 1.16–1.20, 2.06–2.19, and 2.25–2.60, indicating partial to complete enantioseparation. The isothermal titration calorimetry and molecular docking revealed that hydrogen bondings and π‐alkyl interactions played key roles in chiral recognition. The developed method is suitable for assessing enantiomeric purity in antihistamine formulations.