Characterization of Humic Substances
Part of the chemical characterization of humic matter has been discussed in the preceding chapter on chemical composition. It was deemed necessary to cover it in separate chapters because of the many issues or topics, making it too long to include them in one chapter. In addition to the characteristics discussed earlier, humic substances also exhibit molecular weights and very distinctive spectroscopic features. Many scientists have tried using ultravioletvisible, infrared, and nuclear magnetic resonance (NMR) spectroscopy in the identification of various humic substances, with results that are surprisingly reproducible (Orlov, 1985) for materials considered at one time by many to be fake or operational compounds. These remaining characteristics will be discussed in more detail below.