l-Cysteine modified silver nanoparticles-based colorimetric sensing for the sensitive determination of Hg2+ in aqueous solutions

A simple and sensitive colorimetric sensing method was constructed for detection of Hg 2+ in aqueous solutions and based on silver nanoparticles functionalized with l -cysteine ( l -Cys–Ag NPs). In this method, adenosine triphosphate (ATP) induced aggregation of l -Cys–Ag NPs. Simultaneously, the solution colour changed from bright yellow to brown. In the presence of Hg 2+ , Hg 2+ chelated ATP to form a complex and reduce the degree of aggregation of l -Cys–Ag NPs and was accompanied by a colour change from brown to bright yellow. The changing values of absorbance at 390 nm were linearly correlated with concentration of Hg 2+ over the 4.00 × 10 −8 to 1.04 × 10 −6 mol·L −1 range, with a detection limit of 8 nM. This method was used successfully for detection of Hg 2+ in real water samples and performed good selectivity and sensitivity. The recovery range was 91.5–109.1%, indicating that the method has vast application potential for determination of Hg 2+ in the environment.