Sensitive and selective detection of trivalent chromium using Hyper Rayleigh Scattering with 5,5'-dithio--(2-nitrobenzoic acid)-modified gold nanoparticles.

Hyper Rayleigh Scattering (HRS) and absorption spectral assays using surface-modified gold nanoparticles (AuNP) have been developed for sensitive and selective detection of trivalent chromium (Cr) from other metal ions including hexavalent chromium (as CrO). Gold nanoparticles of 13 nm, covalently attached with 5,5'-dithio--(2-nitrobenzoic acid) (AuNP-DTNBA), is used as a probe for both the absorption and HRS assays. AuNP-DTNBA is able to detect Cr at 20 ppb level at pH 6.