Characterization of feat fulvic acid fractions by means of FT-IR, SERS, and 1H, 13C NMR spectroscopy

Fourier transform infrared (FT-IR), surface-enhanced Raman spectroscopy (SERS), and nuclear magnetic resonance (NMR) (H-1 and C-13) have been applied to the characterization of unfractionated and fractionated fulvic acids extracted from an Irish peat. Raman study of these compounds is possible on rough metallic surfaces, which enhance the Raman signal and quench the high fluorescence. The application of these spectroscopic techniques has provided important structural information concerning the aromaticity and the carboxylate and carbohydrate group contents in each fraction. In addition, a SERS study at different pH levels has revealed interesting interfacial behavior of these components based on electric charge and conformational changes.