A sensitive resonance light scattering spectrometry of trace Hg2+ with sulfur ion modified gold nanoparticles

A new resonance light scattering (RLS) spectrometric method for mercury ions (Hg2+) in aqueous solutions with sulfur ion (S2−) modified gold nanoparticles (Au-NPs-S) has been developed in this contribution. It was found that S2− at the surface of Au-NPs resulting from the surface modification can interact with Hg2+ to form very stable S–Hg–S bonds when Hg2+ concentration is lower than that of S2−, resulting in the aggregation of Au-NPs-S and causing enhanced RLS signals. The enhanced RLS intensities (ΔIRLS) characterized at 392 nm were found to be proportional to the concentration of Hg2+ in the range of 0.025–0.25 μmol L−1 with a detection limit (3σ) of 0.013 μmol L−1. Our results showed that this approach has excellent selectivity for Hg2+ over other substances in aqueous solutions.