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Scientific article
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Exhaustive Thin-Layer Cyclic Voltammetry for Absolute Multianalyte Halide Detection

Published inAnalytical Chemistry, vol. 86, no. 22, p. 11387-11395
Publication date2014
Abstract

Water analysis is one of the greatest challenges in the field of environmental analysis. In particular, seawater analysis is often difficult because a large amount of NaCl may mask the determination of other ions, i.e., nutrients, halides, and carbonate species. We demonstrate here the use of thin-layer samples controlled by cyclic voltammetry to analyze water samples for chloride, bromide, and iodide. The fabrication of a microfluidic electrochemical cell based on a Ag/AgX wire (working electrode) inserted into a tubular Nafion membrane is described, which confines the sample solution layer to less than 15 μm. By increasing the applied potential, halide ions present in the thin-layer sample (X–) are electrodeposited on the working electrode as AgX, while their respective counterions are transported across the perm-selective membrane to an outer solution. Thin-layer cyclic voltammetry allows us to obtain separated peaks in mixed samples of these three halides, finding a linear relationship between the halide concentration and the corresponding peak area from about 10–5 to 0.1 M for bromide and iodide and from 10–4 to 0.6 M for chloride. This technique was successfully applied for the halide analysis in tap, mineral, and river water as well as seawater. The proposed methodology is absolute and potentially calibration-free, as evidenced by an observed 2.5% RSD cell to cell reproducibility and independence from the operating temperature.

Citation (ISO format)
CUARTERO BOTIA, Maria et al. Exhaustive Thin-Layer Cyclic Voltammetry for Absolute Multianalyte Halide Detection. In: Analytical Chemistry, 2014, vol. 86, n° 22, p. 11387–11395. doi: 10.1021/ac503344f
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