Limitations in interpreting TMAH thermochemolysis of natural organic matter via consideration of glycine and alanine derivatives

Pyrolysis in the presence of tetramethylammonium hydroxide (TMAH) has been widely used to characterize natural organic matter from various environments and affords methylated counterparts of amino acids, especially glycine and alanine. The present study, based on TMAH pyrolysis of dipeptides, shows that caution should be exercised in interpreting the presence of such compounds, as amino acids other than glycine and alanine may be responsible for the formation of N,N-dimethylglycine methyl ester and N,N-dimethylalanine methyl ester, even when present in peptide bonds.