A simple and rapid colorimetric sensor for sulfide anion detection based on redox reaction of ABTS with Au (III)

A cost-effective and simple colorimetric sensor based on redox reaction of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) with Au (III) ion, has been fabricated for the determination of sulfide (S2-) anion. In the proposed method, colorless ABTS could be oxidized by Au (III) to produce bluish green oxidized ABTS (oxABTS), accompanying with a dramatic absorption band centered at 414 nm. However, in the presence of S2-, Au (III) would be reduced to Au nanoparticles (Au NPs), Au2S NPs or their mixture, inducing a bluish green color fading of ABTS-Au (III) system and a decrease of the absorbance at 414 nm because neither Au NPs nor Au2S NPs were able to oxidize ABTS. Based on this phenomenon, detection of S2- was achieved via its inhibiting effect on the ABTS-Au (III) chromogenic reaction and carried out either by visualizing the solution color change or by measuring the absorbance change of the oxABTS. A linear relationship in the S2- concentration range of 0.5-15 mu M could be acquired with a low detection limit of 0.28 mu M with the help of UV-vis spectroscopy and 1.0 mu M by naked eyes. The as-proposed sensor showed high selectivity toward S2- over other common anions and metallic ions by taking advantage of the sulfide-specific reduction of Au (III). Additionally, such sensing system featured simplicity, rapidity and flexibility, with no requirement of organic probes or nanomaterials. The proposed sensor has been successfully applied to detect S2- in lake water samples with satisfactory results, demonstrating its potential application in environmental water sample detection. (C) 2015 Elsevier B.V. All rights reserved.