CHARACTERIZATION OF THE ACID-BASE PROPERTIES OF HUMIC SUBSTANCES BY CHEMOMETRIC ANALYSIS OF SYNCHRONOUS FLUORESCENCE AND PH POTENTIOMETRIC DATA

• Tipo: Artigo em Revista Científica Internacional
• Data: 1995

Autores

dasilva, jcge (Autor) FCUP; machado, aasc (Autor) FCUP

Revista

Título: Analytical Letters

Vol. 28

Páginas: 2401-2411

ISSN: 0003-2719

Editora: Taylor & Francis

Indexação

ISI Web of Knowledge - 15 Citações

Classificação Científica

FOS: Ciências exactas e naturais > Química

Outras Informações

ID Authenticus: P-001-HEW

Abstract (EN): 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 pK(a)s, 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 pK(a)s: 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.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 11