Investigation of the molecular ion structure for aldononitrile acetate derivatized muramic acid

► This study applied various methods (isotopically labeled reagents, GC-EI-MS, LC-TOF-MS) to investigate molecular weight of aldononitrile acetate derivatized muramic acid. ► This study presented evidence that the derivatized structure of muramic acid is acetylated at 4 positions (3 O-acetylations and 1 N-acetylation) and forms a lactam structure. ► The reports will call up the peers' attention in use of isotope enrichment of muramic acid to study microbial residue dynamics in environment, as isotopic correction based on molecular weight is the fundamental basis for the carbon.