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GC-based Detection of Aldononitrile Acetate Derivatized Glucosamine and Muramic Acid for Microbial Residue Determination in Soil
Published on: May 19, 2012
Investigation of the molecular ion structure for aldononitrile acetate derivatized muramic acid
Chao Liang1, Xudong Zhang, Liping Wei
1DOE Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, WI 53706, USA. chaoliang@wisc.edu
Abstract:
The muramic acid assay is a powerful tool for detecting both intact bacteria and bacterial debris. Past use of aldononitrile acetate derivatization for determining muramic acid in complex samples by gas chromatography/mass spectrometry met detection needs in many instances; however, questions have been raised regarding the interpretation of the derivative structure and its electron ionization fragments. In this study, we applied different methods and proved that the aldononitrile acetate derivatized muramic acid yields a molecular weight of 398, associated with a lactam structure. We also presented evidence that the structure of aldononitrile acetate derivatized muramic acid is acetylated at four positions, 3 O-acetylations and 1N-acetylation. In practical manner, this communication provides a comprehensive reference to researchers using δ(13)C value or ion fragments of the muramic acid marker in biogeochemical studies.
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