Chiral separation of 2-hydroxyglutaric acid on cinchonan carbamate based weak chiral anion exchangers by high-performance liquid chromatography.

d- and l-2-Hydroxyglutaric acid (d- and l-2-HG, respectively) are metabolites related to some diseases (2-hydroxyglutaric aciduria, cancer), which make their identification and analysis crucially important for diagnostic purposes. Chiral stationary phases (CSP) based on tert-butylcarbamoyl-quinine and -quinidine (Chiralpak QN-AX and QD-AX), and the corresponding zwitterionic derivatives (Chiralpak ZWIX(+) and Chiralpak ZWIX(-)) were employed in a weak anion-exchange mechanism to perform the enantiomer separation of d- and l-2-HG without derivatization. QD-AX CSP showed the most promising separation and therefore optimization of eluent, additives, and temperature, required for the baseline separation of solutes was carried out. Depending on experimental conditions resolution values ranged up to 2.0 with run times <20min and MS-compatible conditions. Inversion on the elution order of d- and l-2-HG was possible by using the pseudo-enantiomeric QN-AX CSP.