The identification of plant derived structures in humic materials using three-dimensional NMR spectroscopy.
Here we demonstrate the application of 3-D NMR spectroscopy to structural studies of humic substances, the most abundant of organic compounds on earth. The increased spectral dispersion provided by the additional dimension is proven to be highly advantageous in separating the overlapping signals observed in 2-D spectra. Assignments of the major aliphatic structures and selected aromatic moieties are given as examples. We find that in a forest soil fulvic acid the major aliphatic materials are likely derived from leaf cuticles and further demonstrate that lignin signatures can be identified among the aromatic species. Once identified from the 3-D spectra, these structures can be assigned using the partial information available in 2-D, and in some cases, in the 1-D spectra. These signals are demonstrated to be characteristic to given samples of natural organic matter, and the case is made for their use as indicators of terrestrial biomarkers in mixtures of compounds with unknown origins.
Simpson
André J
AJ
Department of Chemistry, The University of Toronto, Scarborough College, 1265 Military Trail, Scarborough, Ontario, Canada M1C 1A4. asimpson@utsc.utoronto.ca
Kingery
William L
WL
Hatcher
Patrick G
PG
D001578:Benzopyrans / Q000737:chemistry; D015415:Biomarkers / Q000032:analysis; D004784:Environmental Monitoring / Q000379:methods*; D006812:Humic Substances / Q000032:analysis* / Q000737:chemistry; D021621:Imaging, Three-Dimensional; D008031:Lignin / Q000032:analysis / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D010944:Plants / Q000737:chemistry; D012987:Soil; D014197:Trees
D001578:Benzopyrans; D015415:Biomarkers; D006812:Humic Substances; D012987:Soil; D008031:Lignin; C005023:fulvic acid