Amino acid and oligopeptide analysis using Curie-point pyrolysis mass spectrometry with in-situ thermal hydrolysis and methylation: mechanistic considerations

In-situ thermal hydrolysis and methylation-mass spectrometry has been used to study amino acids and oligopeptides containing glycine and alanine. Using tetramethylammonium hydroxide (TMAH) during Curie-point pyrolysis, methylation occurred on groups containing acidic hydrogen moeities (O-H and N-H groups). Multiple methylation reactions were found to occur on compounds containing more than one such functionality. Thermal dehydration reactions to form cyclic dipeptides were observed for oligopeptides as well as amino acids during pyrolysis with TMAH. The methylation and thermal dehydration mechanisms are discussed. In addition, the decomposition mechanisms of amino acids and oligopeptides are presented. (C) 1998 Elsevier Science B.V. All rights reserved.