Polysaccharide-based chiral stationary phases as efficient tools for diastereo- and enantioseparation of natural and synthetic Cinchona alkaloid analogs
A Bajtai, István Ilisz, Róbert Berkecz, Ferenc Fülöp, Wolfgang Lindner, Antal Péter
Abstract
In this study, we present results obtained on the diastereo- and enantioseparation of some basic natural and synthetic Cinchona alkaloid analogs by applying liquid chromatographic (LC) and subcritical fluid chromatographic (SFC) modalities on amylose and cellulose tris-(phenylcarbamate)-based stationary phases using n-hexane/alcohol/DEA or CO2/alcohol/DEA mobile phase systems. Seven chiral stationary phases in their immobilized form were employed to explore their stereoselectivity for a series of closely related group of analytes. The most important characteristics of LC and SFC systems were evaluated through the variation of the applied chromatographic conditions (e.g., the nature and content of the alcohol modifier, the concentration of additives, temperature). The columns Chiralpak IC and IG turned out to be the best in both LC and SFC modalities. Temperature-dependence study indicated enthalpy-controlled separation in most cases; however, separation controlled by entropy was also registered.