Colorimetric Assay for Copper Ion Based on Silver Nanoparticles Functionalized with 1,3-Dimethyl Benzotriazolium Iodide

Measuring the heavy metals in environmental and food samples to evaluate the decontamination of toxic pollutants in the environment is vital for human health. In the current project, a new colorimetric method based on the aggregation of 1,3-dimethyl benzotriazolium iodide Ionic Liquid (BTAIL) stabilized silver nanoparticles (AgNPs) for detection of copper (Cu2+) ion was developed. Aggregation of AgNPs induced by coordinative coupling between Cu2+ and triazole ring of BTAIL. Cu2+ AgNPs aggregates with a color change from yellow to red and a decrease in UV-Vis absorption peak at 400 nm. Under the optimized experimental conditions (pH = 9, reaction time = 3 min, BTAIL volume = 600 μl (0.01 M)) a linear range of 20-100 nM was obtained. Good selectivity and sensitivity toward Cu2+ among the other ions were observed. Finally, real sample results such as green tea, Rosa damascene, Chamaemelum nobile, and Thymus vulgaris indicated that the proposed method could apply precisely for practical applications.