Colorimetric Sensor of Cobalt Ions in Aqueous Solution Using Gold Nanoparticles Modified with Glycyrrhizic Acid

The present work describes simple and green method for the preparation of gold nanoparticles (AuNPs) in aqueous medium under ambient condition and their use in colorimetric detection of cobalt ion. The AuNPs were prepared by an environmentally benign method using glycyrrhizic acid (GA) which is a reducing and stabilizing agent in aqueous medium. The prepared GA-AuNPs were thoroughly characterized by using UV–visible spectroscopy, TEM, TGA, DLS, and FT-IR techniques. The analytical response was linear over the range from 50 mM to 16 μM (R2 = 0.971) with a detection limit of 0.4 nM. The proposed diethyldithiocarbamate-AgNPs-based colorimetric method is simple and highly sensitive for the detection of cobalt ions and allows for the monitoring of cobalt ions directly with naked eye in aqueous medium.