The analysis of the oxazolone derivatives of amino acids by gas chromatography/mass spectroscopy

Abstract

Twelve 2-trifluoromethyl-3-oxazolin-5-ones, (2-TFM-3 oxazolin-5-ones), and one 2-TFM-2-oxazolin-5-one were synthesised from the corresponding a-amino acids. Two of these, the 4-n-butyl, and the 4-(B-methoxycarbonylethyl) oxazolones had not been reported previously. All thirteen 'derivatives' were separated from a mixture by gas liquid chromatography (GLC), using a mixed phase l capillary column whose composition was determined by Laub's method o The mass spectra of the compounds were recorded separately and fragmentation patterns were found to follow the same course proposed 2 during the study of five of these oxazolones. The complex mixture was also analysed by GLC/mass spectrometry (GLC/MS), and it was found possible to assign each peak according to lts fragmentation pattern, and hence, to the parent amino acid. These compounds are easy to prepare and, using a modification of the original method, the author obtained yields as high as ninety five per cento The 'derivatives' of the amino acids serine, glutamine and threonine were not isolated, but the presence of their oxazolone counterpart was demonstrated by GLC/MS of the crude reaction mixture. So far, attempts to prepare and/or detect 'derivatives' of other natural amino acids have failed, but, in the light of the results obtained, further research should prove to be fruitful and eventually provide a sensitive method for the microanalysis of a-amino acid mixtures.