ESEL Paper Review_20110420 by Aamir Alaud-din

 

Title and Authors

 

Title: 2011_05_03_Multivariative curve resolution analysis excitation-emission matrices of fluorescence of humic substances

 

Authors: Maria Cristina G. Antunesa, Joaquim C.G. Esteves da Silvab,*

 

a Centro de Qu?mica ? Vila Real, Chemistry Department, Universidade de Tr?s-os-Montes e Alto Douro, 5000-911 Vila Real, Portugal

b LAQUIPAI, Chemistry Department, Faculdade de Ci?ncias, Universidade d Porto, R. Campo Alegre 687,4169-007 Porto, Portugal

 

Summary

 

This paper presents the variation in intensity of fluorophores for solutions of different concentrations. It shows the similarity and differences in the excitation emission peaks for the identified fluorophores.

 

Humic substance (HS) samples were collected form variety of environments except for commercial humic acid (HA) named Fluka which referred to as HAco. Two fulvic acid (FA) samples were extracted from pinewood soil, labeled as FAo and FAs. Two anthropogenic fulvic acids were obtained from municipal wastewater treatment station labeled as FAcs and FAls. For each HS sample 11 solutions with varying concentrations in the range 5 ? 100mg/L at pH 6 were prepared and analysed spectroscopically.

 

Multivariative curve resolution alternating least square (MCR-ALS) procedure was used to obtain results. Results showed identification of three fluorophores and one component which was recognized as noise. An increase in the concentration of HS increased the fluorescence of first three components whereas fluorescence of fourth component was constant as it was noise.

 

Tables below summarize excitation and emission wavelengths for maximum intensity of three components.

 

    FL1        FL2        FL3    

    Exmax (nm)    Emmax (nm)    Exmax (nm)    Emmax (nm)    Exmax (nm)    Emmax (nm)

FAo    318    453    <346    515    312    <400

FAs    351    469    >380    515    312    <427

FAls    340    432    >380    495    >323    <400

FAcs    329    432    >380    495    323    <400

HAco    323    432    >380    500    318    <400

 

The table shows that anthropogenic FA have similar excitation and emission wavelength except the excitation wavelength for FL1 which are slightly different. FAs from municipal wastewater treatment plant show significant variation in the excitation and emission wavelengths. FL1 and FL2 from HAco show similarity with anthropogenic FA samples while FL3 from HAco is similar to FAo.

 

The results also showed deviation from linear relationship between flourophore intensity and concentration under the concentration range used in this study. However, there was no qualitative disturbance in the fluorescence spectra for the concentration range between 5 and 100mg/L used in this study.

 

By: Aamir Alaud-din

aamiralauddin@gist.ac.kr