Enantioseparation of rabeprazole and omeprazole by nonaqueous capillary electrophoresis with an ephedrine-based ionic liquid as the chiral selector.

An ephedrine-based chiral ionic liquid, (+)-N,N-dimethylephedrinium-bis(trifluoromethanesulfon)imidate (DMP Tf(2) N ), served as both chiral selector and background electrolyte in nonaqueous capillary electrophoresis. The enantioseparation of rabeprazole and omeprazole was achieved in acetonitrile-methanol (60:40 v/v) containing 60 mmDMP Tf(2) N . The influences of separation conditions, including the concentration of DMP Tf(2) N , the electrophoretic media and the buffer, on enantioseparation were evaluated. The mechanism of enantioseparation was investigated and discussed. Ion-pair interaction and hydrogen bonding may be responsible for the main separation mechanism.