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. 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.