Highly selective colorimetric detection and estimation of Hg2+ at nano-molar concentration by silver nanoparticles in the presence of glutathione

• Silver nanoparticles (Ag NPs) were synthesized using Polyalthia longifolia leaf extract.
• Ag NPs characterized by UV–visible spectrophotometer, TEM, XRD and zeta sizer.
• The particles possessed the effective diameter of 5 nm.
• Ag NPs-glutathione conjugates were able to detect Hg2+.
• The conjugated were able to quantify the nano-molar level of Hg2+.

The present study investigated the colorimetric detection of mercury (Hg2+) ions by using silver nanoparticles (Ag NPs) in the presence of glutathione. The nanoparticles used in the study were synthesized biologically by using Polyalthia longifolia leaf extract. The synthesized nanoparticles were characterized by UV–visible spectrophotometer, transmission electron microscope, X-ray diffraction, particle size analyzer and zeta sizer. The particles were spherical in shape and it possesses the effective diameter of 5 nm. The zeta potential of the particles was determined to be −28.6 mV. Ag NPs-glutathione conjugates were able to detect Hg2+ in nanomolar level. Ag NPs-glutathione conjugates upon interaction with Hg2+ changes from yellowish brown to pale yellow and finally colorless. The study may be applied for the qualitative and quantitative estimation of mercury at very low concentration.

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