NEW MS/MS SOFTWARE TOOLS FOR ELUCIDATION OF FRAGMENTATION MECHANISMS IN DI-ACETAMIDES.

MS/MS evaluation of the di-acetamide series and corresponding deutero-acetyl analogs indicated that a step-wise process involving sequential loss of acetyl, ammonia and ketene groups, as well as concerted pathways for the combined loss of these moieties was operative during fragmentation. A mechanism has been proposed for the formation of the (M minus 102)** plus ion which includes a cyclic product, analogous to the one formed after elimination of ammonia from the ethyl ester of lysine. Presentation of the MS/MS spectra in a 'tree' format greatly aided in postulating fragmentation schemes which were consistent with the observed electron impact results since the TSQ 'tree' program is able to display the entire three dimensional MS/MS data field in a convenient and controllable format.