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 (Hg(2+)) in aqueous solutions with sulfur ion (S(2-)) modified gold nanoparticles (Au-NPs-S) has been developed in this contribution. It was found that S(2-) at the surface of Au-NPs resulting from the surface modification can interact with Hg(2+) to form very stable S-Hg-S bonds when Hg(2+) concentration is lower than that of S(2-), resulting in the aggregation of Au-NPs-S and causing enhanced RLS signals. The enhanced RLS intensities (DeltaI(RLS)) characterized at 392 nm were found to be proportional to the concentration of Hg(2+) in the range of 0.025-0.25 micromol L(-1) with a detection limit (3sigma) of 0.013 micromol L(-1). Our results showed that this approach has excellent selectivity for Hg(2+) over other substances in aqueous solutions.