Xanthan Gum-Mediated Silver Nanoparticles for Ultrasensitive Electrochemical Detection of Hg²⁺ Ions from Water

An environmentally safe, efficient, and economical microwave-assisted technique was selected for the production of silver nanoparticles (AgNPs). To prepare uniformly disseminated AgNPs, xanthan gum (XG) was utilized as both a reducing and capping agent. UV–Vis spectroscopy was used to characterize the formed XG-AgNPs, with the absorption band regulated at 414 nm under optimized parameters. Atomic force microscopy was used to reveal the size and shape of XG-AgNPs. The interactions between the XG capping agent and AgNPs observed using Fourier transform infrared spectroscopy. The XG-AgNPs were placed in between glassy carbon electrode and Nafion^® surfaces and then deployed as sensors for voltammetric evaluation of mercury ions (Hg²⁺) using square-wave voltammetry as an analytical mode. Required Nafion^® quantities, electrode behavior, electrolyte characteristics, pH, initial potentials, accumulation potentials, and accumulation durations were all comprehensively investigated. In addition, an electrochemical mechanism for the oxidation of Hg²⁺ was postulated. With an exceptional limit of detection of 0.18 ppb and an R² value of 0.981, the sensors’ measured linear response range was 0.0007–0.002 µM Hg²⁺. Hg²⁺ evaluations were ultimately unaffected by the presence of many coexisting metal ions (Cd²⁺, Pb²⁺, Cr₂O₄, Co²⁺,Cu²⁺, CuSO₄). Spiked water samples were tested using the described approach, with Hg²⁺ recoveries ranging from 97% to 100%.