UV-vis spectroscopic method for the sensitive and selective detection of mercury by silver nanoparticles in presence of alanine

The present investigation reports highly specific and sensitive colorimetric method for the detection of mercuric ion from aqueous samples using silver nanoparticles (Ag NPs). Here, Ag NPs was synthesized by chemical reduction method, and polyvinyl alcohol (PVA) was used as stabilizing agent. The particles were characterized by UV-vis spectrophotometer, scanning electron microscope (SEM), energy-dispersive X-ray spectrometer (EDS), particle size analyser and zeta sizer. The particles were found to be spherical in shape and polydispersed. The effective diameter and zeta potential were determined to be 6 +/- 0.8 nm and - 39.96 +/- 4 mV respectively. The formation of NPs-alanine facilitated the detection of Hg(II) in nano-molar level. The NPs-alanine conjugate solution changed from brownish yellow to colourless with increase in concentration of Hg(II). A good linear relationship was found between absorbance at 398 nm and the Hg(II) concentrations range from 200 to 1000 nM. The paper and hydrogel based probe were developed and found to be highly specific towards the detection of Hg(II). The detection of Hg(II) ions was not influenced by other metal ions. The present investigation may be applied for the assay to detect mercury qualitatively and quantitatively from aqueous samples.