Structural characteristics of the IHSS Suwannee River fulvic and humic acids determined by solution state C-13 NMR spectroscopy

The IHSS Suwannee River fulvic and humic acids have been examined by solution state C-13 NMR spectroscopy. C-13 NMR spectra acquired under quantitative conditions indicated proportions of sp2 hybridized carbons of 60 and 72 percent for the fulvic and humic acids, respectively. Attached Proton Test (APT) experiments clearly resolved the C-13 NMR spectra of both samples into methyl (0-26 ppm), methylene (26-43 ppm), methine (43-62 ppm and 62-92 ppm), protonated aromatic (105-135 ppm) and non-protonated aromatic (135-165 ppm) carbons. The APT spectra also revealed that the aliphatic moieties of the fulvic and humic acids are predominated by branched chain structures. (Auth.)