Biosynthetic Gold Nanoparticles as Sensitive and Selective Colorimetric Method for Mercury Ions

Gold nanoparticles (AuNPs) are widely studied materials that have intense applications in various fields. Different methods use to synthesize the AuNPs, one of them is eco-friendly biological method, known as "green synthesis" a simple and inexpensive method. The Synthesis of AuNPs, using ginger extract is described here. The components found in ginger work as a stabilizing and reducing agent. Hydrogen tetrachloroaurate (HAuCl4) are mixed with the ginger extract to produce AuNPs. The Surface Plasmon Resonance (SPR) measured at λmax = 540 nm. UV-Vis, FTIR and Zeta potential are used to identify AuNPs, as well as AFM and SEM. Data indicate that AuNPs has a spherical structure. The results demonstrate that AuNPs stabilized by ascorbic acid were used as a colorimetric probe for Hg2+ ions, based on the production of (Au-Hg) amalgamate which made changes in their absorbance, due to its ability to reduce Hg2+ to Hg0, to enhance amalgamation. Practically, this procedure has successfully worked to detect Hg2+ in tap water as a sensitive and selective probe with upper limit of detection equal to 120 µM as well as the limit of detection (LOD) equal to 0.65 µM, so the method proved to be sensitive and selective probe.