Synthesis of starch-stabilized Ag nanoparticles and Hg 2+ recognition in aqueous media

Abstract

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. © to the authors 2009.