Abstract
Liquid chromatographic separation of barnidipine enantiomers on physically adsorbed and covalently bonded polysaccharide chiral stationary phases was studied at different temperatures. The separations were accomplished under normal-phase conditions by using different combinations of hexane, organic modifiers (2-propanol and ethanol) as mobile phase. The effects of organic modifiers and the column temperature on retention, separation and resolution were studied. Baseline separation with resolution >5.0 was achieved on coated CHIRALPAK AD-H column containing amylose tris-(3,5-dimethylphenylcarbamate) as a stationary phase using a mobile phase containing of n-hexane: 2-propanol (80:20, v/v) at a flow rate of 0.8mL min-1 at 25°C. The detection was carried out at UV-238 nm. The symmetry was observed at the peaks with no mobile phase additive. The observed differences were explained in terms of the coated and immobilized nature of the two columns. Van’t Hoff plots (ln k′ vs 1/T) and apparent thermodynamic parameters were derived to understand the effect of temperature on enantioseparation of barnidipine enantiomers. The developed method was validated in terms of LOD, LOQ, linearity, accuracy and precision.
