Quantitative Analysis and Separation of Chiral (S)-Ethyl 3-Hydroxyglutarate in Bioconversion Mixtures by LC and TLC

A convenient ion-pair LC procedure was firstly established for rapid analysis of ethyl 3-hydroxyglutarate (3-EHG) in an enzymatic-hydrolysis mixture, and the detection limit was as low as 0.45 μmol L^?1; high repeatability was achieved with intra-day (n = 5) and inter-day (n = 5) relative standard deviation (RSD) values of 1.56 and 2.38%, respectively. The good linearity was established for 3-EHG concentration in the broad range from 0.005 to 0.30 mol L^?1, with a coefficient (r) of 0.9992. (S)- and (R)-3-EHG were separated by normal-phase LC after simple derivatization with (R)-(+)-phenylethanamine, ee value (≥95%) of 3-EHG prepared by Lipase B catalyzed hydrolysis of diethyl 3-hydroxyglutatate (3-DHG) was determined after optimization of the mobile phase, and the RSD was 0.75% (n = 9) for repeatability. The results showed that the above methods were highly reproducible and reliable for analysis and separation of (S)-3-EHG from bioconversion mixture.