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Article

Colorimetric Chemosensor Array for Determination of Halides

1
Department of Chemistry, Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic
2
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; https://doi.org/10.3390/chemosensors9020039
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. https://doi.org/10.3390/chemosensors9020039

AMA Style

Šídlo M, Lubal P, Anzenbacher P Jr.. Colorimetric Chemosensor Array for Determination of Halides. Chemosensors. 2021; 9(2):39. https://doi.org/10.3390/chemosensors9020039

Chicago/Turabian Style

Šídlo, Michal, Přemysl Lubal, and Pavel Anzenbacher Jr. 2021. "Colorimetric Chemosensor Array for Determination of Halides" Chemosensors 9, no. 2: 39. https://doi.org/10.3390/chemosensors9020039

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