RESUMEN
Liquid chromatographic separation of darunavir enantiomers on covalently bonded and physically adsorbed 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, 1-propanol and ethanol), and diethylamine as mobile phase solvents. The effect of organic modifiers and the column temperature on retention, separation, and resolution was investigated. 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, ln α vs. 1/T) and apparent thermodynamic parameters were derived to understand the effect of temperature on separation.
RESUMEN
Liquid chromatographic separation of stereoisomers of darunavir on Chiralpak AD-H, a column containing the stationary phase coated with amylose tris(3,5-dimethylphenylcarbamate) as a chiral selector, was studied under normal-phase conditions at different temperatures between 20 and 50°C. The effect of quality and quantity of different polar organic modifiers viz: methanol, ethanol, 1-propanol, and 2-propanol in the mobile phase as well as column temperature on retention, separation, and resolution was investigated and optimized. The optimum separation was accomplished using a mobile phase composed of n-hexane/ethanol/diethyl amine (80:20:0.1 v/v/v) at 40°C. Apparent thermodynamic parameters ΔH(0) and ΔS* were derived from the Van't Hoff plots (lnk' versus 1/T) and used to explain the strength of interactions between the stereoisomers and amylose tris(3,5-dimethylphenylcarbamate) coated chiral stationary phase.