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Colorimetric Chemosensor Array for Determination of Halides

Department of Chemistry, Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic
Center for Photochemical Sciences and Department of Chemistry, Bowling Green State University, Bowling Green, OH 43403, USA
Author to whom correspondence should be addressed.
Academic Editor: Jose Vicente Ros Lis
Chemosensors 2021, 9(2), 39;
Received: 31 December 2020 / Revised: 7 February 2021 / Accepted: 12 February 2021 / Published: 18 February 2021
The halide anions are essential for supporting life. Therefore, halide anion analyses are of paramount importance. For this reason, we have performed both qualitative and quantitative ana- lyses of halides (chloride, bromide, iodide) using the Tl(III) complex of azodye, 4-(2-pyridylazo)re- sorcinol (PAR), a potential new chemical reagent/sensor that utilizes the substitution reaction whereas the Tl(III)PAR complex reacts with a halide to yield a more stable thallium(III)-halide while releasing the PAR ligand in a process accompanied by color change of the solution. The experimental conditions (e.g., pH, ratio metal ion-to-ligand ratio, etc.) for the substitution reaction between the metal complex and a halide were optimized to achieve increased sensitivity and a lower limit of detection (chloride 7 mM, bromide 0.15 mM, iodide 0.05 mM). It is demonstrated that this single chemosensor can, due to release of colored PAR ligand and the associated analyte-specific changes in the UV/VIS spectra, be employed for a multicomponent analysis of mixtures of anions (chloride + bromide, chloride + iodide, bromide + iodide). The spectrophotometric data evaluated by artificial neural networks (ANNs) enable distinguishing among the halides and to determine halide species concentrations in a mixture. The Tl(III)-PAR complex was also used to construct sensor arrays utilizing a standard 96-well plate format where the output was recorded at several wavelengths (up to 7) using a conventional plate reader. It is shown that the data obtained using a digital scanner employing only three different input channels may also be successfully used for a subsequent ANN analysis. The results of all approaches utilized for data evaluation were similar. To increase the practical utility of the chemosensor, we have developed a test paper strip indicator useful for routine naked-eye visual determination of halides. This test can also be used for halide anion determination in solutions using densitometer. The methodology described in this paper can be used for a simple, inexpensive, and fast routine analysis both in a laboratory as well as in a field setting. View Full-Text
Keywords: metal complex; halide analysis; anion chemosensor; artificial neural network (ANN); multicomponent analysis; microplate reader/digital scanner; test strip paper(s) metal complex; halide analysis; anion chemosensor; artificial neural network (ANN); multicomponent analysis; microplate reader/digital scanner; test strip paper(s)
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MDPI and ACS Style

Šídlo, M.; Lubal, P.; Anzenbacher, P., Jr. Colorimetric Chemosensor Array for Determination of Halides. Chemosensors 2021, 9, 39.

AMA Style

Šídlo M, Lubal P, Anzenbacher P Jr.. Colorimetric Chemosensor Array for Determination of Halides. Chemosensors. 2021; 9(2):39.

Chicago/Turabian Style

Šídlo, Michal, Přemysl Lubal, and Pavel Anzenbacher Jr. 2021. "Colorimetric Chemosensor Array for Determination of Halides" Chemosensors 9, no. 2: 39.

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