Sensitive and selective colorimetric detection of Cu2+ in aqueous medium via aggregation of thiomalic acid functionalized Ag nanoparticles
Abstract
A simple and effective colorimetric method for determination of Cu2+ in real samples was developed. In this method, thiomalic acid functionalized silver nanoparticles (TMA-AgNPs) were prepared and changes in solution color, induced by the aggregation of TMA-AgNPs in the presence of Cu2+, were employed for quantitative analysis. The surface plasmon resonance (SPR) band of our synthesized TMA-AgNPs was located at 392 nm and shifted to a longer wavelength after aggregation due to the interactions between carboxylate and Cu2+. A band intensity ratio of A455/(A392 − A455) was constructed and used to correlate with the concentration of Cu2+. A linear relationship was found with a linear response up to 50 nM of Cu2+. Due to the formation of a stable carboxylate Cu2+ complex, highly sensitive detection of Cu2+ was achieved with the estimated detection limit approaching 1 nM. Moreover, the formation of the stable complex leads to high selectivity in the detection of Cu2+, which was verified by examination of 12 other metal ions. In the detection of Cu2+ in real samples, results indicated that our proposed method is simple, sensitive and selective for application in such measurements.