Prussian Blue nanoparticles as optical probes for visual and spectrophotometric determination of silver ions

The authors report on a method for visual and spectrophotometric determination of silver (I) by using Prussian Blue nanoparticles (PB NPs) as a colorimetric probe. It is based on the finding that the blue PB NPs are converted into colorless silver ferrocyanide ions in the presence of Ag(I) due to the establishment of a dissolution-precipitation equilibrium. The change in absorbance at 700 nm is related to the concentration of Ag(I) in the range from 0.01 to 3 μM. The visual detection limit is 3 μM. The assay has a good selectivity for Ag(I) over other common ions. It was successfully applied to the determination of Ag(I) in spiked samples of river and lake waters. Schematic presentation of a visual and spectrophotometric method for determination of silver(I) by using Prussian Blue nanoparticles (PB NPs) as optical probes.