Fluorescence quenching of three molecular weight fractions of a soil fulvic acid by UO2(II)

被引:18
作者
Shin, HS [1 ]
Hong, KH [1 ]
Lee, MH [1 ]
Cho, YH [1 ]
Lee, CW [1 ]
机构
[1] Korea Atom Energy Res Inst, Nucl Environm Res Div, Taejon 305600, South Korea
关键词
soil fulvic acid; UO2(II) complexation; synchronous fluorescence; self-modeling mixture analysis;
D O I
10.1016/S0039-9140(00)00567-1
中图分类号
O65 [分析化学];
学科分类号
070302 ; 081704 ;
摘要
A soil fulvic acid isolated from a Korean forest was divided into three different molecular weight fractions (F1: less than 220 Da; F2: 220-1000 Da; and F3: 1000-4000 Dal by gel filtration chromatography and the fractions were studied by synchronous fluorescence (SyF) spectroscopy. Analysis of the SyF spectra for the fulvic acid fractions showed that the fractions with molecules of larger sizes have a higher content of condensed aromatic compounds. The information about their interaction with UO2(II) ions in an aqueous solution (100 mg l(-1) of fulvic acid, in 0.1 M NaClO4 at pH 3.5) was obtained from the measurement of SyF spectra at increasing concentrations of metal ions. Self-modeling mixture analysis of the quenching spectra gives two distinct peak components having a maximum peak position of 386 (type I) and 498 nm (type II) for all the size-fractionated fulvic acids. From the analysis of the quenching profiles of the peaks, using a non-linear method, the concentration of binding sites (C-L), and the corresponding stability constants (log K) were calculated. The stability constants of the UO2(II)-fulvate complexes ranged from 4.10 to 5.33, and increased with higher molecular weight fractions, which indicates a stronger affinity for UO2(II) in the fraction with molecules of larger size. (C) 2001 Elsevier Science B.V. All rights reserved.
引用
收藏
页码:791 / 799
页数:9
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