Heavy Metal Detection via AgNPs Assay

Regarding the contamination by heavy metal ions, the tests were conducted using the following salts: NaAsO₂ and Cd(NO₃)₂ (purchased from Sigma Aldrich (Milan, Italy) and used without further purification). For these solutions, deionized water was used (electrical resistivity 18.2 MΩ*cm at room temperature). UV-vis spectra were performed by using single-use UV-PMMA cuvettes with Perkin-Elmer Lambda 750 UV-vis-NIR for sensing test characterization. Protocol of sensing tests: a fixed volume of our AgNPs (1.6 mg/mL) was mixed with a fixed volume of heavy metal ions solution at a specific concentration and, after 5 minutes of interaction, the optical absorption spectra were collected. This protocol described here was successfully tested on silver nanoparticles, stabilized by the hydrophilic ligand sodium 3-mercapto-1-propanesulfonate, whose response to several metal ions at different concentrations in the range of few ppm was tested by UV-vis spectroscopy [16 (link)].