The noble metal nanoparticles (NPs), including gold nanorods (AuNRs), gold nanospheres (AuNSs) and silver nanoplates (AgNPTs), were synthesized and Tween 20 stabilized NPs (Tween 20-NPs) were used as the probes for determining Hg(2+). Hg(2+) was determined based on the strong affinity between Au (Ag) and Hg. Hg(2+) was reduced to Hg in the presence of sodium borohydride. Hg interacts with the NPs and the diameter of the NPs decreases with the increase of Hg(2+) concentration, which causes the shift in absorption peak of Tween 20-NPs. The peak shifts are linearly related to Hg(2+) concentrations. Compared with AuNSs and AgNPTs, when the AuNRs was used, the sensitivity for determining Hg(2+) was higher. The developed method shows a good selectivity for Hg(2+) and can be applied to the determination of Hg(2+) in water samples.
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