Bimetallic gold–silver nanocluster fluorescent probes for Cr(iii) and Cr(vi)

Abstract

Bimetallic gold–silver nanoclusters (AuAgNCs) have been successfully synthesized using 11-mercaptoundecanoic acid (11-MUA) as a reducing agent and capping ligand. It was found that the fluorescence of AuAgNCs was quenched selectively by Cr(III) when using ethylenediaminetetraacetic acid (EDTA) as the masking agent and there was a good detection linear range for Cr(III) from 0.08 μM to 6 μM with high sensitivity (LOD = 0.05 μM, S/N = 3). At the same time, the experimental results show that the AuAgNCs were not sensitive to the ascorbic acid (AA) reductant and they can thus be utilized to detect Cr(VI) indirectly by employing an additional reducing step. Linear quenching of fluorescence intensity related to Cr(VI) concentration was over the range of 0.6 μM to 10 μM with a LOD of 0.3 μM (S/N = 3). In addition, the recovery experiments further demonstrated that this AuAgNCs based method can achieve the chemical speciation and quantitative determination of Cr(III) and Cr(VI) in real water samples.