Use of various β-cyclodextrin derivatives as chiral selectors for the enantiomeric separation of higenamine by capillary electrophoresis

Abstract

In the present work, four β-cyclodextrin derivatives including neutral (methyl- and hydroxypropyl-) and anionic (carboxymethyl- and sulfated-) β-cyclodextrin derivatives have been tested for the enantioseparation of higenamine by capillary electrophoretic method. To our knowledge, there is no literature about using capillary electrophoresis for the chiral separation of higenamine. To achieve the best resolution in the presence of each β-cyclodextrin derivative, the primary factors affecting separation efficiency, such as buffer pH and concentration of β-cyclodextrin derivatives, were investigated. All enantiomeric separation was performed by 30mmol/L phosphate buffer with an applied voltage of 20kV or −20kV. Under the optimum conditions, four β-cyclodextrin derivatives (methyl-β-cyclodextrin, hydroxypropyl-β-cyclodextrin, carboxymethyl-β-cyclodextrin and sulfated-β-cyclodextrin) exhibited good separation performances for higenamine with the Rs value of 2.3, 5.8, 9.4 and 11.7 respectively. As well as the chiral separation abilities of different β-cyclodextrin derivatives were compared. Moreover, the method for determining R-(+)-higenamine in Nelumbins plumula was proposed employing carboxymethyl-β-cyclodextrin as the chiral selector.