Gas chromatographic behaviour of amino acid oxazolidinones : Response to flame ionization and electron capture detectors

Abstract

The use of 1,3-dichloro-1,1,3,3-tetrafluoroacetone for derivatization of α-amino acids offers two important advantages. Firstly, the amino group, which is coupled with the carboxylic group in a five membered ring, does not require further treatment with an anhydride or silyl reagent and, secondly, the next reaction step, the esterification of the remaining protonic groups, can be performed immediately after the first reaction without evaporation of the reaction medium. Moreover, the oxazolidinones show very good chromatographic properties and a high response to the electron capture detector (ECD) comparable with that of lindane. The response to the flame ionization detector (FID) is nearly the same as that of trifluoroacetylated methyl esters of amino acids. The oxazolidinones of tyrosine and mono- and diiodotyrosines were prepared and, after treatment with acetic, trifluoroacetic, heptafluorobutyric or pivalic anhydride or with hexamethyldisilazane, they were chromatographed on silicone phases. The relative molar responses to hexadecane (FID) and lindane (ECD) were determined.