2007
DOI: 10.1590/s0100-40422007000200003
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Anéis aromáticos condensados e relação E4/E6: estudo de ácidos húmicos de gleissolos por RMN de 13C no estado sólido utilizando a técnica CP/MAS desacoplamento defasado

Abstract: Recebido em 6/6/05; aceito em 31/5/06; publicado na web em 26/9/06 CONDENSED AROMATIC RINGS AND E 4 /E 6 RATIO: HUMIC ACIDS IN GLEYSOILS STUDIED BY NMR CP/MAS 13 C, AND DIPOLAR DEPHASING. In this work, seven samples of humic acids extracted from gleysoils were investigated. These studies, using NMR CP/MAS 13 C techniques, did not show significant correlation between the E 4 /E 6 ratio and the degree of aromaticity. However, dipolar dephasing (DD) measurements of condensed aromatic or substituted carbons showed… Show more

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Cited by 30 publications
(9 citation statements)
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(17 reference statements)
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“…The areas relative to these resonance intervals were used to evaluate the degree of hydrophobicity (hydrophobic/hydrophilic carbons, HB/HI) of the humic fractions [27][28][29][30][31]. All integral regions were also corrected for the areas of spinning side bands (SSB) when they appeared in the spectra.…”
Section: Characterizationmentioning
confidence: 99%
“…The areas relative to these resonance intervals were used to evaluate the degree of hydrophobicity (hydrophobic/hydrophilic carbons, HB/HI) of the humic fractions [27][28][29][30][31]. All integral regions were also corrected for the areas of spinning side bands (SSB) when they appeared in the spectra.…”
Section: Characterizationmentioning
confidence: 99%
“…In aquatic environments FA is the dominant type of HS. 6 The study of humic substances structure is carried out through different spectroscopy techniques [7][8][9][10] as well as microscopies. 11,12 Among these techniques, the fluorescence spectroscopy 13,14 and the atomic force microscopy (AFM) [15][16][17][18] have been used to characterize and determine the humic substances structure.…”
Section: Introductionmentioning
confidence: 99%
“…It was reported that the E 4 /E 6 ratio is mainly related to the size of the humic substances (Chen et al, 1977). The NMR CP/MAS 13 C techniques with polar dephashing (DD) measurements of condensed aromatic or substituted carbons demonstrated a negative significant correlation (R 2 =0.94) with the E 4 /E 6 ratio, indicating that this ratio identifies the degree of condensation of aromatic rings (Saab and Martin-Neto, 2007).…”
Section: Resultsmentioning
confidence: 96%