Selectivity of amylose tris(3,5-dimethylphenyl-carbamate) chiral stationary phase as a function of its structure altered by changing concentration of ethanol or 2-propanol mobile-phase modifier.

In a previous publication, solid-state NMR data showed that the structure of Chiralpak AD chiral stationary phase (CSP) was altered by changing the concentration of ethanol or 2-propanol modifier in the chromatographic mobile phase. This present paper reports the effect of the CSP structural change on chiral selectivity alpha. The enantiomers of a series of compounds were chromatographed using ethanol or 2-propanol in various concentrations as mobile-phase modifier and the alpha values were determined. Changes of alpha were observed for some enantiomeric pairs when ethanol and 2-propanol concentrations were varied. These data correlate with previous findings on the structural changes of the CSP. Not every enantiomeric pair showed changes in alpha as the alcohol concentration was varied, indicating that the chiral selectivity depends not only on the CSP's structure, but also on the structures of the analytes.