Recognition of amino acid chirality in gas chromatography by sequential use of enantiomeric stationary phases

Abstract

In order to achieve a reliable identification of amino acid enantiomers by using gas chromatography, sequential use of enantiomeric phases have been evaluated. It is based on that the elution order of D- and L-amino acid esters is reversed when the chirality of the phase is reversed. For this kind of works, the reliability of retention values is essential. Therefore, we have first measured the retention indices and separation factors of various protein and nonprotein amino acid enantiomers on N-lauroyl-L-valine-t-butylamide (phase-L) and N-lauroyl-D-valine-t-butylamide (phase-D). These phases have shown the highest separability among the phases ever reported. The columns used were whisker walled glass capillary columns. It was revealed that the retention indices on phase-L show little difference over the experimental temperature range while those on phase-D show gradual increase with the temperature rise. The separation factors on both phases decreased with the temperature increase. The reproducibility of the retention indices were good enough for the peak identification. It should be noted that there are differences between the retention indices on the two phases, which should be elucidated later. The determination of the optical purities of the phases and identification of the moieties of an antibiotic were done successfully for the application experiments. For the identification, it was also useful to check the separation factors. © 1981, The Japan Society for Analytical Chemistry. All rights reserved.