Capillary gas chromatography using electron capture or selected ion monitoring detection for the determination of muramic acid, diaminopimelic acid and the ratio of d/l-alanine in bacteria

Gas chromatographic analyses of muramic acid, diaminopimelic acid and D-alaline, which are specific components of the bacterial cell wall, have been performed using electron capture or selected ion monitoring detection. Intact cells or peptidogylycan preparations were hydrolyzed in HCl and DCl. After purification by cation exchange chromatography, followed by conversion to the N-heptafluobutyrliso-butyl esters, the components were separated on a 25 m fused silica column coated with SE-54 or on a chiral glass capillary column. The detection limits for muramic acid and diaminopimelic acid were about 10 pg using either detection method and the procedure has the potential sensitivity for detecting about 3 × 10⁵ bacterial cells, e.g., Escherichia coli. Mass spectrometric determination of the d/l ratio of alamine in intact cells of Group A streptococci, type M 15 and in peptidogylcan preparations thereof indicated the proportions 10.2% and 10.5% of D-alanine, respectively. The values uncorrected for racemization during acid hydrolysis were 10.3% and 10.7%, respectively.