Exploring a new rapid colorimetric detection method of Cu2+ with high sensitivity and selectivity

In this study, we propose a new rapid colorimetric detection method of Cu2+ with high sensitivity and selectivity utilizing starch-stabilized silver nanoparticles (AgNPs), which are synthesized by a green chemistry way. AgNPs gradually become smaller in the presence of Cu2+ due to redox reaction between Ag and Cu2+, which results in color change and UV-vis absorption decrease of the nanoparticle dispersion. Therefore, Cu2+ could be recognized by visualizing the color change of AgNPs dispersed by naked eyes, and quantitatively measured by UV-vis spectra. There is a linear relationship between the absorbance ratio (A(0)/A, at 400 nm) and the concentration of Cu2+ ranging from 0.1 mu M to 10 mu M. The linear coefficient is 0.9968. The lowest detectable concentration is 0.5 mu M by naked eyes. Furthermore, the selectivity of this detection system for Cu2+ is excellent comparing with other metal ions, such as Hg2+, Co2+, Ba2+, Zn2+, Na+, Fe3+, Sr2+, Pb2+, Cd2+, Ni2+, Ca2+, Mg2+, Mn2+ and K+. The high sensitivity and selectivity of the Cu2+ detection system are ascribed to the unique redox reaction between Ag and Cu2+. (C) 2012 Elsevier B.V. All rights reserved.