Chiral separation of short chain aliphatic hydroxycarboxylic acids on cinchonan carbamate-based weak chiral anion exchangers and zwitterionic chiral ion exchangers

- Direct enantioseparation of eight aliphatic hydroxycarboxylic acids (HCA) is reported.
- Elution order for enantiomers of HCA is determined on four cinchona alkaloid derived chiral stationary phases.
- Enantioselective cryo-HPLC (−20 °C) allows baseline resolution for 3-hydroxybutyric acid.
- MS-compatible conditions for the baseline separation of studied solutes are described.

Chiral short chain aliphatic hydrocarboxylic acids (HCAs) are common compounds being part of different biological processes. In order to control and understand these processes is of pivotal importance to determine the identity of the involved enantiomer or their enantiomeric ratio. In this study the capacity of quinine- and quinidine-derived chiral stationary phases to perform the enantioseparation of eight chiral HCAs (tartaric acid, isocitric acid, malic acid, glyceric acid, 2-hydroxyglutaric acid, 2-hydroxybutyric acid, lactic acid and 3-hydroxybutyric acid) was evaluated. MS-compatible conditions consisting of ACN/MeOH mixtures as eluents with formic acid, acetic acid and/or their ammonium salts as additives, temperatures between 10 and 25 °C (except for −20 °C for 3-hydroxybutyric acid) and a flow rate of 1.00 mL/min yielded full baseline resolution for all studied HCAs. Elution order for the HCA enantiomers was determined revealing different behaviors between the studied compounds.