Europium(III) Complexed by HPSEC Size-Fractions of a Vertisol Humic Acid: Small Differences Evidenced by Time-Resolved Luminescence Spectroscopy

Pascal E. Reiller (1) , Julien Brevet (2) , Antonio Nebbioso (3) , Alessandro Piccolo (3)

1 LSRM - Laboratoire de Spéciation des Radionucléides et des Molécules
2 LAMBE - Laboratoire Analyse et Modélisation pour la Biologie et l'Environnement
3 University of Naples Federico II = Università degli studi di Napoli Federico II

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.

Keywords: Humic acid; Europium; fractionation; complexation; luminescence

Keywords: fluorescence

Domains: Inorganic chemistry; Organic chemistry

Pascal E. Reiller, Julien Brevet, Antonio Nebbioso, Alessandro Piccolo. Europium(III) Complexed by HPSEC Size-Fractions of a Vertisol Humic Acid: Small Differences Evidenced by Time-Resolved Luminescence Spectroscopy. Spectrochimica Acta Part A : Molecular Spectroscopy [1967-1993], 2011, 78 (3), pp.1173-1179. ⟨10.1016/j.saa.2010.12.075⟩. ⟨cea-00563824⟩