Ruggedness of enantiomeric separation by capillary electrophoresis and high-performance liquid chromatography with methylated cyclodextrins as chiral selectors

Abstract

When applying cyclodextrin (CD) derivatives as chiral selectors for enantiomeric separation in different separation methods, the difference in degree of substitution (DS) and substitution pattern of the CD derivative may lead to complications. Seven different methylated β-cyclodextrin derivatives were tested as additives in the background electrolyte in capillary electrophoresis (CE) and as an additive to the mobile phase in high-performance liquid chromatography (HPLC). The substitution patterns of heptakis(2,6-di-O-methyl)-β-CD (DIMEB) and randomly methylated β-CD samples were compared using a simple thin-layer chromatography method. The CE method was sensitive to the quality of the chiral selector and it was solute dependent. While the enantiomeric separation of N-methylephedrine and terbutaline was excellent with all DIMEBs, in the case of hexobarbital, the separation failed with one DIMEB sample. The HPLC method was less sensitive to the quality of the chiral selector than the CE method.