title: Simultaneous measurement of Cr(III) and Cr(VI) in freshwaters with a single Diffusive Gradients in Thin Films device.
abstract: Few attempts have been made to sample labile chromium with the DGT passive sampler (Diffusive Gradients in Thin Films) and, currently, no single device allows the simultaneous determination of both Cr(III) and Cr(VI). In this work, a procedure based on only one device combined with innovative selective elution is evaluated to assess chromium speciation. A zirconium binding gel is used to accumulate both Cr(III) and Cr(VI). Cr(VI) is quantitatively and selectively eluted by NaOH, allowing the subsequent determination of Cr(III). Accurate quantification of both species is demonstrated in synthetic solutions for pH ranging from 4 to 6 and ionic strength ranging from 10(-3) to 5×10(-2)M. Cr(VI) quantification is altered only for [SO4(2-)]≥5×10(-3)M. The method allows successful quantification of labile Cr(III) and Cr(VI) in spiked natural water. The limit of quantification of the procedure is suitable for trace level monitoring (0.03µgL(-1) for Cr(VI) and 1µgL(-1) for Cr(III), for a one-week deployment at 20°C) and the effective capacity of the sampler (∼25µg for each Cr oxidation state) should allow long term deployments. These results highlight the potential of this new procedure for a simple and effective chromium speciation analysis in natural waters.
authors.affiliation: University of Limoges, Research group on Water, Soil and Environment (GRESE), 123 Avenue Albert Thomas, 87060 Limoges Cedex, France.
authors.forename: Delphine
authors.initials: D
authors.lastname: Devillers
authors.affiliation: University of Limoges, Research group on Water, Soil and Environment (GRESE), 123 Avenue Albert Thomas, 87060 Limoges Cedex, France. Electronic address: remy.buzier@unilim.fr.
authors.forename: Rémy
authors.initials: R
authors.lastname: Buzier
authors.affiliation: University of Limoges, Research group on Water, Soil and Environment (GRESE), 123 Avenue Albert Thomas, 87060 Limoges Cedex, France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Simon
authors.affiliation: University of Limoges, Research group on Water, Soil and Environment (GRESE), 123 Avenue Albert Thomas, 87060 Limoges Cedex, France.
authors.forename: Adeline
authors.initials: A
authors.lastname: Charriau
authors.affiliation: University of Limoges, Research group on Water, Soil and Environment (GRESE), 123 Avenue Albert Thomas, 87060 Limoges Cedex, France.
authors.forename: Gilles
authors.initials: G
authors.lastname: Guibaud
keywords: Chromium speciation; DGT; Passive sampling; Selective elution; Water quality