Study of the acid-base properties of fulvic acid-like substances extracted from senescent leaves of eucalyptus and oak

The acid-base properties of two fulvic acids (FA) extracted from senescent leaves of eucalyptus and oak were characterized by carrying out potentiometric titrations at two FA concentrations and four ionic strengths (0.005 M <[KNO(3)] <1.0 M). Experimental data were analyzed by means of the mas...

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Published inAnalytical and bioanalytical chemistry Vol. 375; no. 4; pp. 523 - 526
Main Authors Antelo, Juan, López, Rocio, Fiol, Sarah, Antelo, Juan M, Arce, Florencio
Format Journal Article
LanguageEnglish
Published Germany 01.02.2003
Subjects
Acid-Base Equilibrium - physiology
Benzopyrans - analysis
Plant Leaves - chemistry
Plant Leaves - growth & development
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Summary:The acid-base properties of two fulvic acids (FA) extracted from senescent leaves of eucalyptus and oak were characterized by carrying out potentiometric titrations at two FA concentrations and four ionic strengths (0.005 M <[KNO(3)] <1.0 M). Experimental data were analyzed by means of the master curve approach, which includes an electrostatic spherical double layer model, and the Langmuir-Freundlich isotherm was used to fit the data. The contribution of the electrostatic effect to the proton binding reaction was lower than that observed for soil fulvic acids. The chemical heterogeneity of both samples was described by two acid sites with p Ks of about 4 and 7.5, the most abundant being the carboxylic site of p K = 4.
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ISSN:1618-2642
DOI:10.1007/s00216-002-1726-8