New and simple procedure for the determination of muramic acid in chemically complex environments by gas chromatography–ion trap tandem mass spectrometry

A gas chromatographic–ion trap tandem mass spectrometric method was developed for the quantification of muramic acid, a marker of bacterial peptidoglycan, in environmental and clinical specimens. Samples (bacteria, house dust and urine) were heated in methanolic hydrochloric acid overnight and extracted with hexane for removal of hydrophobic compounds. The aqueous phase was evaporated and heated in acetic anhydride and pyridine after which the product, the acetate derivative, was washed with dilute hydrochloric acid and water. The described method is both rapid and simple to apply, and produces a stable derivative. It should become widely used for measuring peptidoglycan in chemically complex environments.