Please use this identifier to cite or link to this item: http://www.alice.cnptia.embrapa.br/alice/handle/doc/339740
Research center of Embrapa/Collection: Embrapa Solos - Artigo em periódico indexado (ALICE)
Date Issued: 2008
Type of Material: Artigo em periódico indexado (ALICE)
Authors: NOVOTNY, E. H.
KNICKER, H.
MARTIN NETO, L.
AZEREDO, R. B. V.
HAYES, M. H. B.
Additional Information: ETELVINO HENRIQUE NOVOTNY, CNPS; H. Knicker, Lehrstuhl fur Bodenkunde, Technische Universitat Munchen; LADISLAU MARTIN NETO, DE/P&D; R. B. V. AZEREDO, UFF; M. H. B. HAYES, Chemical and Environmental Sciences University of Limerick.
Title: Effect of residual vanadyl ions on the spectroscopic analysis of humic acids: a multivariate approach.
Publisher: European Journal of Soil Science, Oxford, v. 59, n. 3, p. 439-444, Jun. 2008.
Language: en
Keywords: Análise espectroscópica
Ácidos húmicos
Description: In a study of the vanadyl (VO2þ)-humic acids system, the residual vanadyl ion suppressed fluorescence and specific electron paramagnetic resonance (EPR) and NMR signals. In the case of NMR, the proton rotating frame relaxation times (T1qH) indicate that this suppression is due to an inefficient H-C cross polarization, which is a consequence of a shortening of T1qH. Principal components analysis (PCA) facilitated the isolation of the effect of the VO2þ ion and indicated that the organic free radical signal was due to at least two paramagnetic centres and that the VO2þ ion preferentially suppressed the species whose electronic density is delocalized over O atoms (greater g-factor). additionally, the newly obtained variables (principal components ? PC) indicated that, as the result of the more intense tillage a relative increase occurred in the accumulation of: (i) recalcitrant structures; (ii) lignin and long-chain alkyl structures; and (iii) organic free radicals with smaller g-factors.
Data Created: 2008-12-09
Appears in Collections:Artigo em periódico indexado (CNPS)

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