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Isotope‐Filtered 4D NMR Spectroscopy for Structure Determination of Humic Substances
Author(s) -
Bell Nicholle G. A.,
Michalchuk Adam A. L.,
Blackburn John W. T.,
Graham Margaret C.,
Uhrín Dušan
Publication year - 2015
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201503321
Subject(s) - chemistry , molecule , characterization (materials science) , nuclear magnetic resonance spectroscopy , fulvic acid , spectroscopy , humic acid , isotopic labeling , soil organic matter , computational chemistry , organic chemistry , nanotechnology , soil water , materials science , environmental science , soil science , fertilizer , physics , quantum mechanics
Abstract Humic substances, the main component of soil organic matter, could form an integral part of green and sustainable solutions to the soil fertility problem. However, their global‐scale application is hindered from both scientific and regulatory perspectives by the lack of understanding of the molecular make‐up of these chromatographically inseparable mixtures containing thousands of molecules. Here we show how multidimensional NMR spectroscopy of isotopically tagged molecules enables structure characterization of humic compounds. We illustrate this approach by identifying major substitution patterns of phenolic aromatic moieties of a peat soil fulvic acid, an operational fraction of humic substances. Our methodology represents a paradigm shift in the use of NMR active tags in structure determination of small molecules in complex mixtures. Unlike previous tagging methodologies that focused on the signals of the tags, we utilize tags to directly probe the identity of the molecules they are attached to.