Liquid chromatographic separation and thermodynamic investigation of stereoisomers of darunavir on Chiralpak AD-H column.

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.