highly stable and sensitive colorimetric visualization of trivalent chromium using amido black 10b-stabilized silver nanoparticles

Here, we report a highly stable and sensitive colorimetric assay for cr3+ based on amido black 10b-stabilized silver nanoparticles (agnps) as the probes. the detection mechanism is that the coordination interaction between cr3+ and amido black 10b on the surface of agnps causes the cross-linking/aggregation of amido black-stabilized agnps, generating a redshift of the absorption peak and a color change from yellow to pink. under the optimized assay conditions, this colorimetric assay displays a good linear relationship (r 2 = 0.996) between relative absorbance ratios and the concentration of cr3+ in the range of 0.05–20 μm, and the limit of detection (lod) was estimated to be 0.01 μm by the uv-vis spectra and 15 μm by the naked eye. additionally, the colorimetric assay shows a good selectivity over other metal ions, and it is successfully applied to detection of cr3+ in tap water, lake water, and river water samples with satisfactory recoveries.