Characterization of the Acid-Base Properties of Humic Substances by Chemometric Analysis of Synchronous Fluorescence and pH Potentiometric Data
作者:
J. C. G. Esteves da Silva,
A. A. S. C. Machado,
期刊:
Analytical Letters
(Taylor Available online 1995)
卷期:
Volume 28,
issue 13
页码: 2401-2411
ISSN:0003-2719
年代: 1995
DOI:10.1080/00032719508000381
出版商: Taylor & Francis Group
关键词: Humic substances;marine fulvic acids;evolving factor analysis;synchronous fluorescence analysis;acid-base properties
数据来源: Taylor
摘要:
A procedure for the analysis of the acid-base characteristics of humic substances based on a self-modeling analysis of synchronous fluorescence spectra, collected at varying pH, and on a non-linear least squares adjustment of potentiometic pH data, is described. The data analysis methodology consists of two steps: first, the number of acid-base systems and the corresponding spectra and distribution diagrams are calculated by evolving factor analysis (EFA) with concentration constraints of the spectroscopic data; second, the potentiometric data is analyzed by a standard non-linear least square procedure using as fixed parameters the number of components and their pKas, determined in the first step of the analysis. As an example, for a sample of marine fulvic acids studied at pH between 2 and 11, four acid-base systems were found with average pKas: 3.1, 4.8, 8.0 and 10.0. The concentrations of the corresponding systems were: 2.55(5), 1.95(7), 0.14(4) and 1.8(3) meq/g.
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