A Comparative Study of the Application of Fluorescence Excitation-Emission Matrices Combined with Parallel Factor Analysis and Nonnegative Matrix Factorization in the Analysis of Zn Complexation by Humic Acids
PBN-AR
Instytucja
Instytut Agrofizyki im. Bohdana Dobrzańskiego Polskiej Akademii Nauk
Informacje podstawowe
Główny język publikacji
en
Czasopismo
SENSORS
ISSN
1424-8220
EISSN
Wydawca
MDPI AG
DOI
URL
Rok publikacji
2016
Numer zeszytu
1760
Strony od-do
1-20
Numer tomu
16(10)
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Słowa kluczowe
en
metal complexation
fluorescence spectroscopy
excitation-emission matrices
decomposition methods in modeling metal complexation
humic acids
Open access
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Inne
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Język
en
Treść
The main aim of this study was the application of excitation-emission fluorescence matrices (EEMs) combined with two decomposition methods: parallel factor analysis (PARAFAC) and nonnegative matrix factorization (NMF) to study the interaction mechanisms between humic acids (HAs) and Zn(II) over a wide concentration range (0–50 mg·dm−3). The influence of HA properties on Zn(II) complexation was also investigated. Stability constants, quenching degree and complexation capacity were estimated for binding sites found in raw EEM, EEM-PARAFAC and EEM-NMF data using mathematical models. A combination of EEM fluorescence analysis with one of the proposed decomposition methods enabled separation of overlapping binding sites and yielded more accurate calculations of the binding parameters. PARAFAC and NMF processing allowed finding binding sites invisible in a few raw EEM datasets as well as finding totally new maxima attributed to structures of the lowest humification. Decomposed data showed an increase in Zn complexation with an increase in humification, aromaticity and molecular weight of HAs. EEM-PARAFAC analysis also revealed that the most stable compounds were formed by structures containing the highest amounts of nitrogen. The content of oxygen-functional groups did not influence the binding parameters, mainly due to fact of higher competition of metal cation with protons. EEM spectra coupled with NMF and especially PARAFAC processing gave more adequate assessments of interactions as compared to raw EEM data and should be especially recommended for modeling of complexation processes where the fluorescence intensities (FI) changes are weak or where the processes are interfered with by the presence of other fluorophores.
Cechy publikacji
ORIGINAL_ARTICLE
Inne
System-identifier
755138
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