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Abstract

Glutathione-capped gold nanoparticles (GSH-AuNPs) were prepared by chemical reduction of HAuCl 4 using glutathione (GSH) as the capping agent and NaBH 4 as the reducing agent. GSH-AuNPs were characterized by UV-Vis spectroscopy, IR spectroscopy, and transmission electron microscopy (TEM). The pH value of the synthesized GSH-AuNPs solution was also measured to be 7.20. A colorimetric method for Cd 2+ was developed based on the aggregation of GSH-AuNPs induced by its interaction with Cd 2+ , which is also exhibited as a red to blue color change. At pH 6, the GSH-AuNPs-based colorimetric method exhibited higher sensitivity and better linearity at 700 nm. Stable absorbance readings were established at 10 min reaction time. Under the optimized conditions, this method was found to be linear (linearity of 0.993 r 2 ) in the concentration range of 0.3-0.55 mM with sensitivity of 3.43 A.U./mM and detection limit of 1.35  10 -3 mM. With its good analytical performance such as low cost, sensitivity, rapidity, and visual detection, the GSH-AuNPs-based method described here demonstrates potential application for the detection of Cd 2+ in actual water sample for assessment and monitoring purpose.