, , Zenkevich G. Igor
Background. Application of simple regularities and the general principles along with direct use of reference retention index data is a useful approach for reliable structure determination of compounds by GC-MS. Objective. Interpretation of anomaly in elution order of alkyl esters of alkoxycarbonyl derivatives of glycine and alanine. Method. Preliminary derivatization to alkyl esters of N-alkoxycarbonyl analogs for GC-MS analysis of amino acids. Results. Alkyl es¬ters of N-alkoxycarbonyl derivatives of alanine (Alkyl = C2H5, n- and iso- C3H7) elute prior to the same deri¬va¬tives of glycine, despite the presen¬ce of addi¬tional methyl group at C(2). Elution order is reversed for methyl es¬ters of N-methoxycarbonyl derivatives. Conclusion. The peculiar behavior of alkyl esters of N-alkoxycarbonyl derivatives of glycine and alanine agrees with the concepts of gas chromatography and the known retention index regularities of organic compounds. Decrease of retention index values is a result of an introduction of additional methyl group to a carbon atom connected to two polar fragments in a molecule CH2XY. The dependence of the difference of retention index values for homologs of the types of CH3-CHXY and CH2XY vs. the total mass of fragments (X + Y) is similar to those for other sub-groups of analytes.
amino acids, glycin, alanin", alkyl ester, N-alkoxycarbonyl derivatives, standard non- polar stationary phases, retention indices, elution order anomaly