We propose a simple, fast and sensitive colorimetric method for the determination of Cd2+ using 1,13-bis(8-quinolyl)-1,4,7,10,13-pentaoxatridecane modified silver nanoparticles. The addition of Cd2+ causes the aggregation of AgNPs, while other ions do not have such effect. As a result, the color of the solution changes from yellow to red which can be detected using naked eye or by UV–Vis spectroscopy. The aggregation of the AgNPs is confirmed by UV–Vis and transmission electron microscopy. Limit of detection is found to be 0.016 μM for Cd2+ ions. A linear calibration plot is correlated to the concentration of cadmium ion in the 0.5–6.0 μM range with the naked-eye detection limit of 2.0 μM. The method was successfully applied to determine Cd2+ in water and urine samples and gave recoveries that ranged from 93.3 to 98.6%.
