Versatility of cinchona-based zwitterionic chiral stationary phases: Enantiomer and diastereomer separations of non-protected oligopeptides utilizing a multi-modal chiral recognition mechanism

► We apply zwitterionic stationary phases for chiral separations of small peptides. ► Enantiomers of the all-l/all-d type and d/l sequence isomers are separated. ► Retention depends on efficient simultaneous double ion pairing. ► H bonding with the peptide backbone strongly contributes to chiral recognition. ► Combination of structural features of peptide and selector determines outcome.