Soil organic matter chemistry. Part 1. Characterization of several humic preparations by proton and carbon‐13 nuclear magnetic resonance spectroscopy

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Abstract
Both laboratory and commercial preparations of humic substances (HSs) such as fulvic acids and humic acids along with HC1‐HF preparation of Manitoba peat soil organic matter were characterized using Fourier Transformation (FT) proton (1H) and carbon‐13 (13C) nuclear magnetic resonance (NMR) spectroscopy. All the samples were dissolved in a solution of 0.4 N NaOD in D2O. In the case of ‘H‐NMR spectroscopy, all the investigated humic samples displayed resonance absorption peaks in the region of 1–4 ppm indicating the likely presence of aliphatic protons in the preparations. However, with the exception of one fulvic acid preparation (extracted from Manitoba Carrol clay‐loam soil with 0.5 N NaOH), 1H‐NMR spectra of all other samples provided evidence for strong aromatic character. The aliphatic and aromatic characteristics of such samples of HSs were further confirmed with the aid of 13C‐NMR spectra.