Nanogold resonance Rayleigh scattering determination of trace Cr3+

Nanogolds (AuNPs) were synthesized with the citrate reduction of HAuCl4. In pH 3.0 glycine-HCl buffer solution (0.20 mol/L), AuNPs do not aggregate. In the presence of Cr (III), that Cr(III) could form astable Cr(III)-citrate complex with the citrate on surface of AuNP in 1: 2 binding stoichiometry, and the AuNPs were aggregated to big AuNPs clusters. that led to the resonance Rayleigh scattering (RRS) peak at 530 nm increased greatly. Under the selected conditions, the increased RRS intensity (Delta I-530nm) is linear to Cr(III) concentration in the range of 0.25-5.0 mu mol/L. This RRS method was applied to determination of Cr(III) in synthetic samples, with satisfactory results. Cr(VI) was also detected after reduction to Cr(III).