Sensitive and selective colorimetric detection of cadmium(II) using gold nanoparticles modified with 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole

We have developed a simple, sensitive and selective colorimetric method for the detection of cadmium(II) (Cd 2+ ) using gold nanoparticles modified with 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole. Organic solvents or additives are not required. It is found that Cd 2+ induces the aggregation of the modified Au-NPs via chelation, leading to a color change from red to blue. This change can be seen with bare eyes, and monitored by UV–vis spectroscopy, transmission electron microscopy and dynamic light scattering. The detection limit is 30 nM (at a signal-to-noise ratio of 3). The new approach was successfully applied to the detection of Cd 2+ in spiked samples of tap water and lake water, and the results agree well with those obtained by flame atomic absorption spectroscopy. A simple, sensitive and selective colorimetric method was developed for the detection of Cd 2+ , where 4-amino-3-hydrazino-5-mercapto-1,2,4-triazol (AHMT) modified gold nanoparticles (AuNPs) were used as optical probes. The presence of Cd 2+ induced the aggregation of the AHMT-AuNPs through the chelation process. This approach was successfully applied for the detection of Cd 2+ in spiked samples of tap water and lake water.