Abstract: Herein a novel colorimetric method based upon gold nanoparticles (AuNPs) was developed for the detection of lead in water. The method was based on the fact that the presence of glutathione (GSH) can prevent the aggregation of AuNPs at a high concentration of NaCl solution, while addition of Pb2+ to the solution will cause the aggregation of AuNPs, leading to changes in the color of AuNPs. Under the optimum conditions, the absorbance was found to be linearly proportional to the concentration of lead ion within the range of 10.36–1 036 ng/mL, with a limit of detection (LOD) of 2.072 ng/mL. The recoveries of Pb2+ from spiked samples were 99.1%–103.6%, and the precision expressed as relative standard deviation was less than 4%. Moreover, this assay showed good sensitivity, stability and reproducibility and thus could be used for rapid detection of lead ion in water.

Key words: glutathione, gold nanoparticles, colorimetric detection, lead ion