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.

A gold nanorods (GNRs) nonaggregation-based colorimetric probe has been developed for the detection of S(2-) 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 S(2-) ions to form Au(2)S complexes on the GNRs surfaces. The GNRs probe exhibits highly sensitive and selective response toward S(2-) with a wide linear range from 10.0 to 10000.0 μM. The proposed colorimetric probe can be used to visibly detect S(2-) 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.