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 Cu 2+ 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 Cu 2+ due to redox reaction between Ag and Cu 2+ , which results in color change and UV–vis absorption decrease of the nanoparticle dispersion. Therefore, Cu 2+ 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 Cu 2+ ranging from 0.1   μM to 10   μM. The linear coefficient is 0.9968. The lowest detectable concentration is 0.5   μM by naked eyes. Furthermore, the selectivity of this detection system for Cu 2+ is excellent comparing with other metal ions , such as Hg 2+ , Co 2+ , Ba 2+ , Zn 2+ , Na + , Fe 3+ , Sr 2+ , Pb 2+ , Cd 2+ , Ni 2+ , Ca 2+ , Mg 2+ , Mn 2+ and K + . The high sensitivity and selectivity of the Cu 2+ detection system are ascribed to the unique redox reaction between Ag and Cu 2+ .