Synthesis of Starch-Stabilized Ag Nanoparticles and Hg2+Recognition in Aqueous Media

The starch-stabilized Ag nanoparticles were successfully synthesized via a reduction approach and characterized with SPR UV/Vis spectroscopy, TEM, and HRTEM. By utilizing the redox reaction between Ag nanoparticles and Hg 2+ , and the resulted decrease in UV/Vis signal, we develop a colorimetric method for detection of Hg 2+ ion. A linear relationship stands between the absorbance intensity of the Ag nanoparticles and the concentration of Hg 2+ ion over the range from 10 ppb to 1 ppm at the absorption of 390 nm. The detection limit for Hg 2+ ions in homogeneous aqueous solutions is estimated to be ~5 ppb. This system shows excellent selectivity for Hg 2+ over other metal ions including Na + , K + , Ba 2+ , Mg 2+ , Ca 2+ , Fe 3+ , and Cd 2+ . The results shown herein have potential implications in the development of new colorimetric sensors for easy and selective detection and monitoring of mercuric ions in aqueous solutions.