Colorimetric detection of cadmium ions using modified silver nanoparticles

Metal ion sensors are a significant and challenging area in the analytical sciences. In this study, the use of grape juice for bio-synthesizing of silver nanoparticles (AgNPs) and using it for simple and rapid colorimetric detection of Cd2+ ions is described. The as-prepared AgNPs were characterized by standard analytical techniques including UV–visible and FTIR spectroscopic methods and transmission electron microscopy (TEM). The plasmon resonance band of the silver nanoparticles was observed at 410 nm and it was found that its intensity is related to the grape juice concentration and pH. The TEM image showed the average size of 5–10 nm for AgNPs. The detection of Cd2+ ions was based on the changes of absorbance due to complex formation of the metal ion. The colorimetric detection of Cd2+ was led to a linear dynamic range from 0 to 150 µmol/L (r2 = 0.9993) and a low detection limit of 4.95 µmol/L for cadmium in aqueous solution. These results are close to or better than the previous reports. This bio-synthesized AgNPs can be used as simple alternative design for colorimetric sensing of Cd2+ in water samples.