期刊
TALANTA
卷 81, 期 1-2, 页码 556-564出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.talanta.2009.12.043
关键词
Chromium determination; Rotating-disc bismuth film electrode; Square wave adsorptive cathodic stripping voltammetry; Chromium speciation
资金
- Portuguese Foundation for Science and Technology (FCT) [528]
- Centro de Ciencias Moleculares e Materiais (CCMM)
An adsorptive stripping voltammetric protocol coupled with a rotating-disc bismuth film electrode for the determination and speciation of chromium (III) and chromium (VI) in the presence of diethylenetriaminepentaacetic acid (DTPA) is presented. The developed methodology involves a mass-transport controlled preconcentration step, during which a Cr(III)-DTPA complex is adsorbed onto a pre-plated rotating-disc bismuth film electrode held at -0.4V, followed by a reductive square wave stripping scan. At -1.07V vs. Ag/AgCl, a peak is recorded due to the catalytic reduction of Cr(III)-DTPA to Cr(II)-DTPA. As a result of different chemical behaviours of Cr(III) and Cr(VI) in the presence of DTPA, the corresponding voltammetric signals presented different stabilities in time. A univariate optimization study was performed with several experimental parameters as variables. For Cr(VI) and total chromium, Cr(III) + Cr(VI), an accumulation time of 60 s at -0.4 V vs. Ag/AgCl resulted in detection limits of 0.336 and 0.414 nM and quantification limits of 1.12 and 1.40 nM, respectively. The relative standard deviation for 10 measurements of 5.0 nM chromate was 2.4%. Interference of other electroactive trace metals and surfactants was considered. A simple speciation scheme was proposed and satisfactorily applied to Cr(III) and Cr(VI) determinations in river water samples. (C) 2009 Elsevier B.V. All rights reserved.
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