title: In situ redox speciation analysis of chromium in water by diffusive gradients in thin films using a DE81 anion exchange membrane.
abstract: A method for the in situ redox speciation analysis of chromium in water by the diffusive gradients in thin films (DGT) technique using a DE81 anion exchange membrane was successfully developed. For the selective uptake of Cr(VI), a DGT device containing an anion exchange membrane DE81 (cellulose acetate chromatographic paper) was used (DE81-DGT), while selective uptake of Cr(III) was carried out using DGT devices containing the Chelex-100 resin (Chelex-100-DGT). A correlation coefficient of 0.993 was obtained for the linearity of the immersion curves (mass versus time) using DE81-DGT. The diffusion coefficient values for Cr(VI) through the agarose diffusive layer were equal to 4.89±0.5×10(-6)cm(2)s(-1) and 3.95±0.02×10(-6)cm(2)s(-1) (T=23±1°C, I=0.03molL(-1) NaNO3) were obtained by using diffusion cell and immersion curves, respectively. The retention of Cr(VI) by the DE81 membrane in a synthetic sample and river water was not affected by the pH over a wide range 4-9). Recoveries of Cr(VI) between 90% and 120% from solutions of ionic strength ranging from 0.01 to 0. 5molL(-1) NaNO3 were achieved. Finally, the redox speciation analysis of Cr(III) and Cr(VI) in spiked river water and synthetic samples was performed with recoveries greater than 80% and 87% by using Chelex-100-DGT and DE81-DGT devices, respectively. Those results were in excellent agreement with the diphenylcarbazide spectrophotometric method.
authors.affiliation: Centro de Estudos Ambientais, UNESP - Univ Estadual Paulista, Av. 24-A, 1515, CEP 13506-900 Rio Claro, SP, Brazil.
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Suárez
authors.affiliation: Centro de Estudos Ambientais, UNESP - Univ Estadual Paulista, Av. 24-A, 1515, CEP 13506-900 Rio Claro, SP, Brazil.
authors.forename: Thays V
authors.initials: TV
authors.lastname: de Simone
authors.affiliation: Centro de Estudos Ambientais, UNESP - Univ Estadual Paulista, Av. 24-A, 1515, CEP 13506-900 Rio Claro, SP, Brazil; Instituto de Geociências e Ciências Exatas, UNESP - Univ Estadual Paulista, Av. 24-A, 1515, CEP 13506-900 Rio Claro, SP, Brazil. Electronic address: amenega@rc.unesp.br.
authors.forename: Amauri A
authors.initials: AA
authors.lastname: Menegário
authors.affiliation: Centro de Estudos Ambientais, UNESP - Univ Estadual Paulista, Av. 24-A, 1515, CEP 13506-900 Rio Claro, SP, Brazil.
authors.forename: Ana M C M
authors.initials: AM
authors.lastname: Rolisola
authors.affiliation: Centro de Estudos Ambientais, UNESP - Univ Estadual Paulista, Av. 24-A, 1515, CEP 13506-900 Rio Claro, SP, Brazil.
authors.forename: Karen S
authors.initials: KS
authors.lastname: Luko
authors.affiliation: Centro de Estudos Ambientais, UNESP - Univ Estadual Paulista, Av. 24-A, 1515, CEP 13506-900 Rio Claro, SP, Brazil.
authors.forename: Didier
authors.initials: D
authors.lastname: Gastmans
authors.affiliation: Instituto de Geociências e Ciências Exatas, UNESP - Univ Estadual Paulista, Av. 24-A, 1515, CEP 13506-900 Rio Claro, SP, Brazil.
authors.forename: Fabiano T
authors.initials: FT
authors.lastname: da Conceição
authors.affiliation: Centro de Estudos Ambientais, UNESP - Univ Estadual Paulista, Av. 24-A, 1515, CEP 13506-900 Rio Claro, SP, Brazil; Instituto de Geociências e Ciências Exatas, UNESP - Univ Estadual Paulista, Av. 24-A, 1515, CEP 13506-900 Rio Claro, SP, Brazil.
authors.forename: Chang H
authors.initials: CH
authors.lastname: Kiang
keywords: Chromium speciation; DE81 membrane; Diffusive gradients; Paper-based DGT; Passive sampler; Thin films