Molecular fluorescence spectroscopy and mixture analysis for the evaluation of the complexation between humic acid and UO2 2+

Abstract

Summary Humic acid (HA) was fractionated by gel permeation chromatography and the complexation of the obtained three fractions with UO2 2+ was examined by synchronous fluorescence spectroscopy combined with SIMPLISMA, which is one of the mixture analysis methods. Most of the fluorescence of HA resulted from the lowest molecular weight fraction, and the quenching behavior of this fraction was similar to that of unfractionated HA. After the spectral resolution by SIMPLISMA, two components, which were differently quenched with UO2 2+, were extracted for both cases. The complexing parameters, the apparent stability constant and the concentration of complexing sites, were evaluated for each component and compared between unfractionated HA and the lowest molecular weight fraction.