Stationary phase-related investigations of quinine-based zwitterionic chiral stationary phases operated in anion-, cation-, and zwitterion-exchange modes.

摘要: The concept of recently introduced Cinchona alkaloid-type zwitterionic chiral stationary phases (CSPs) is based on fusing key cation- and anion-exchange (CX, AX) moieties in one single low-molecular mass selector (SO) with the resulting CSPs allowing enantiomer separations a wide range ionizable analytes comprising acids, bases, compounds. Herein, we report principal, systematic investigations ion-exchange-type retention mechanisms available novel nonaqueous polar organic mode. Typical CX AX processes, corresponding to parent ion exchangers, are confirmed also for CSPs. Also mechanism leading recognition zwitterions was found be exchange mediated zwitterion-exchange (ZX) In both modes additional group within SO besides site responsible respective ion-exchange process could characterized as an intramolecular counterion (IMCI) that effectively participates equilibria thus, contributes solute elution. ZX mode oppositely charged groups were not only sites simultaneous pairing analyte but functioned IMCIs at same time. main practical consequences IMCI feature significant reduction amounts even elimination acidic basic additives required eluent systems afford elution while still providing faster analysis than ion-exchanger-type set ten structurally different employed this study facilitated establishment correlations between chromatographic behavior particular elements, thereby supporting understanding working principles these packing materials molecular level.