A colorimetric probe for online analysis of sulfide based on the red shifts of longitudinal surface plasmon resonance absorption resulting from the stripping of gold nanorods Original Research Article

A gold nanorods (GNRs) nonaggregation-based colorimetric probe has been developed for the detection of S2− based on that the longitudinal surface plasmon resonance absorption wavelength (LPAW) of GNRs red shifts (Δλ) and the color of the solution distinctly changes on account of the faster stripping of GNRs along longitudinal axis than transverse axis in the process of GNRs reacting with S2− ions to form Au2S complexes on the GNRs surfaces. The GNRs probe exhibits highly sensitive and selective response toward S2− with a wide linear range from 10.0 to 10000.0 μM. The proposed colorimetric probe can be used to visibly detect S2− in water samples on line in 15 min with the results agreeing well with those of the optical sensor, showing its great practicality. Moreover, the detection mechanism of the probe is also discussed.