Chemical ionzation mass spectra of amino acids and derivatives. Occurrence and fragmentation of ion-molecule reaction products

The Chemical ionization mass spectra of free amino acids, their amides, methyl esters and Na-acetyl derivatgives, using methane as reagent gas, are presented, The occurrence and fragmentation of ion-molecules reaction products are discussed. A preference for a head to tail, configuration of the association complex [2M + 1]+ is postulated to esplain promienent fragmentation pathways of this complex. Interesting fragmentation pathways have been found with onithine, arginine and citrulline