We investigated various botanical classes of peat by electron spin resonance (ESR) spectroscopy. ESR parameters were line height and width of high-spin ferric complexes, line height and width of the organic radical, the g value of organic radical, and the microwave power for saturation of the organic radical. Qualitatively, these parameters vary more or less with the botanical classification and the degree of decomposition.
ESR parameters have also been subjected to principal components (PC) analysis, which gives a nice display of peat data. The partial least-squares (PLS) technique was used to evaluate whether any relationships exist between ESR data and basic peat characteristics (R value, percentage of humification, calorific value, etc.) and amino acid constituents of peat.
Klason lignin data obtained from the same peat samples were found to be more homogeneous and to contain about 10 times more of the solely detected organic radicals. Carbon-13 solid-state NMR indicates that these are large aromatic complexes.
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