Derivatization and Multidimensional Gas-Chromatographic Resolution of α-Alkyl and α-Dialkyl Amino Acid Enantiomers

The quantitative resolution of amino acid enantiomers is crucial to a number of fields of bioanalytical chemistry, including food and plant analysis, metabolomics, medicinal chemistry, and archeochemistry. The enantioselective analysis of alpha-dialkyl amino acids, however, has proven more difficult than for proteinaceous alpha-protonated amino acids. Herein, the development of an analytical method capable of base-line resolving enantiomers of alpha-alkyl and alpha-dialkyl amino acids in two chromatographic dimensions is reported. It was found that enantiomers of alpha-dialkyl amino acids can be readily resolved with the use of an enantioselective Chirasil-Val stationary phase in the first chromatographic dimension and a polyethylene glycol stationary phase in the second dimension. These data offer new possibilities for the enantioselective resolution and precise quantification of non-biological alpha-dialkyl amino acids. This methodology will subsequently be applied particularly towards enantioselective analyses of samples relevant for understanding of the origin of homochirality on Earth such as meteorites, comets, and interstellar ices.