Chiral separation of polar substances like native amino acids and peptides represent a challenging chromatographic task. Due to the increasing number of peptidic pharmaceuticals, particularly, short antimicrobial peptides, this challenge is nowadays more frequently accepted. However, from the plethora of available chiral stationary phases, only few show required enantioselectivity towards ionized analytes, and some limitations in the chiral resolution of peptides by commercial chiral zwitterion ion exchangers have already been documented. Therefore, we have introduced a dipeptide unit into the structure of zwitterionic Cinchona-based selector with the aim to achieve higher similarity between the selector and the peptide analytes.
M. Mžika, N. Váňová, M. Kriegelstein, M. Hroch, Differential adsorption of an analyte and its D4, D5 and 13C6 labeled analogues combined with instrument-specific carry-over issues: The Achilles' heel of ibrutinib TDM, Journal of Pharmaceutical and Biomedical Analysis 206 (2001). Link to the article.