Spectroscopic studies on soil organic fractions—II. IR and 1H-NMR spectra of methylated and unmethylated fulvic acids |
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| Authors: | P. Ruggiero O. Sciacovelli C. Testini F.S. Interesse |
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| Affiliation: | 1. Istituto de Chimica Agraria, Facoltà di Agraria, Università degli Studi, Via Amendola 165/a, Bari, Italy;2. Istituto di Chimica Fisica, Facoltà di Scienze, Università degli Studi, Via Amendola 173, Bari, Italy;3. Istituto di Chimica Agraria, Facoltà di Agraria, Università degli Studi, Via Enrico De Nicola 10, Sassari, Italy;4. Istituto di Industrie Agrarie, Facoltà di Agraria, Università degli Studi, Via Amendola 165/a, Bari, Italy |
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| Abstract: | The IR and 1H-NMR spectra of fulvic acids (FA) are discussed. The FA, extracted by traditional methods, were fractionated on the basis of molecular weight (m.w.). Three fractions were obtained labelled FA I (m.w. > ～ 2000), FA II (m.w. > ～ 12000) and FA III (～2000 < m.w. < ～ 12000). Fraction FA II was methylated with CH3I-Ag2O. The 1H-NMR spectra of unmethylated FA fractions show some signals common to all three fractions and some differences in the 3–5 ppm range due to the resonances of OCH3 and O-CH2 groups. The proton spectrum of the methylated fraction shows absorption areas for OCH3 groups of phenols and carboxyls. The results confirm that NMR spectroscopy is a convenient technique which can contribute to defining the chemical structure of humic substances. |
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