A circular dichroism sensor for Ni(2+) and Co(2+) based on L-cysteine capped cadmium sulfide quantum dots.

Analytica chimica acta (2015-03-31)
Wimonsiri Tedsana, Thawatchai Tuntulani, Wittaya Ngeontae
RESUMEN

A new circular dichroism sensor for detecting Ni(2+) and Co(2+) was proposed for the first time using chiral chelating quantum dots. The detection principle was based on changing of circular dichroism signals of the chiral quantum dots when forming a chiral complex with Ni(2+) or Co(2+). L-Cysteine capped cadmium sulfide quantum dots (L-Cyst-CdS QDs) were proposed as a chiral probe. The CD spectrum of L-Cyst-CdS QDs was significantly changed in the presence of Ni(2+) and Co(2+). On the other hand, other studied cations did not alter the original CD spectrum. Moreover, when increasing the concentration of Ni(2+) or Co(2+), the intensity of the CD spectrum linearly increased as a function of concentration and could be useful for the quantitative analysis. The proposed CD sensor showed linear working concentration ranges of 10-60 μM and 4-80 μM with low detection limits of 7.33 μМ and 1.13 μM for the detection of Ni(2+) and Co(2+), respectively. Parameters possibly affected the detection sensitivity such as solution pH and incubation time were studied and optimized. The proposed sensor was applied to detect Ni(2+) and Co(2+) in real water samples, and the results agreed well with the analysis using the standard ICP-OES.

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Sigma-Aldrich
Nitric acid, ACS reagent, 70%
Sigma-Aldrich
L-Cysteine, 97%
Sigma-Aldrich
Nitric acid, 70%, purified by redistillation, ≥99.999% trace metals basis
Sigma-Aldrich
L-Cysteine, from non-animal source, BioReagent, suitable for cell culture, ≥98%
Sigma-Aldrich
Sodium sulfide
SAFC
L-Cysteine
Sigma-Aldrich
Nitric acid, puriss. p.a., 65.0-67.0%
Sigma-Aldrich
L-Cysteine, BioUltra, ≥98.5% (RT)
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Nitric acid, ACS reagent, ≥90.0%
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Nitric acid concentrate, 0.1 M HNO3 in water (0.1N), eluent concentrate for IC
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Sodium sulfide hydrate, ≥60%, scales
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L-Cysteine, ≥97%, FG
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Nitric acid, red, fuming, HNO3 >90 %
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L-Cysteine, certified reference material, TraceCERT®
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L-Cysteine, produced by Wacker Chemie AG, Burghausen, Germany, ≥98.0%
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Nitric-14N acid solution, ~10 N in H2O, 99.99 atom % 14N