Europium(III) complexed by HPSEC size-fractions of a vertisol humic acid: small differences evidenced by time-resolved luminescence spectroscopy.
The size fractionation of a humic acid (HA) by high performance size exclusion chromatography (HPSEC) was used as a proxy for the filtration effect during HA transport through a porous medium with minimum specific chemical interactions. The modification of the Eu(III)-HA complexes' formation with the different size-fractions, as compared to the bulk HA, was studied in time-resolved luminescence spectroscopy (TRLS). Clear modifications in Eu(III)-HA complexes' structures were shown and related to the molecular characteristics of the separated size-fractions. The properties of most of size-fractions did not induce a major alteration of the affinity towards Eu(III). Only the most hydrophilic fractions eluted in the tail of the chromatographic peak, representing about 11% of total fractions-weight, gave some significantly different parameters. Using a simplistic complexation model, it was found that the available complexation sites decreased with the size reduction of humic fractions.
CE Saclay, CEA/DEN/DANS/DPC/SECR, Laboratoire de Spéciation des Radionucléides et des Molécules, Gif-sur-Yvette, France. pascal.reiller@cea.fr
Pascal E
PE
Reiller
Julien
J
Brevet
Antonio
A
Nebbioso
Alessandro
A
Piccolo
D002850:Chromatography, Gel / Q000379:methods*; D005063:Europium / Q000737:chemistry*; D006812:Humic Substances / Q000032:analysis*; D049449:Luminescence; D013057:Spectrum Analysis / Q000379:methods*
D006812:Humic Substances; D005063:Europium