On the mechanisms of enantiomer separations by chiral thin-layer chromatography on silica gel, and implications when densitometric detection is used. A mini review

Abstract

Summary Enantiomer separations have been one of the most important and, simultaneously, one of the most difficult to accomplish analytical (and technological) tasks, present at the top of separation scientists' agenda since the early sixties of the last century. Awareness of their importance has been awakened by an infamous case of the racemic drug thalidomide, a widely advertised sedative drug which had unexpected teratogenic activity in pregnant women that resulted in thousands of ‘flipper babies’ born in the late fifties and the early sixties in many countries around the world. Since that time, separation scientists have developed numerous methods for enantiomer separation, basically by use of gas chromatography (GC), high-performance liquid chromatography (HPLC), and capillary electrophoresis (CE). In this respect, planar chromatography has remained to a large extent an undervalued enantiomer separation technique, despite separation performance sufficient to separate a pair of enantiomers. The large n...