A highly selective colorimetric sulfide assay based on the inhibition of the peroxidase-like activity of copper nanoclusters

The authors report that sulfide ions are capable of inhibiting the peroxidase-like activity of copper nanoclusters (CuNCs). The catalytic activity of CuNCs toward the oxidation of the chromogenic substrate 3,3′,5,5′-tetramethylbenzidine by H₂O₂ is remarkably decreased in the presence of sulfide. Based on this finding, a colorimetric assay was developed for the rapid determination of sulfide. Best operated at a wavelength of 652 nm, it has a 0.5 μM detection limit. The method is highly selective and has been successfully applied to the quantification of sulfide in environmental water samples.

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Graphical abstract The catalytic activity of CuNCs toward the oxidation of 3,3′,5,5′-tetramethylbenzidine by H₂O₂ is remarkably decreased in the presence of sulfide ions. This finding has been applied to design a method for colorimetric quantification of sulfide ions in environmental samples.