A novel catalytic kinetic method for the determination of mercury(ii) in water samples

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%.

Design and Characterization of Electrochemical Sensor for the Determination of Mercury(II) Ion in Real Samples Based upon a New Schiff Base Derivative as an Ionophore

The present paper provides a description of the design, characterization, and use of a Hg2+ selective electrode (Hg2+-SE) for the determination of Hg2+ at ultra-traces levels in a variety of real samples. The ionophore in the proposed electrode is a new Schiff base, namely 4-bromo-2-[(4-methoxyphenylimino)methyl]phenol (BMPMP). All factors affecting electrode response including polymeric membrane composition, concentration of internal solution, pH sample solution, and response time were optimized. The optimum response of our electrode was obtained with the following polymeric membrane composition (% w/w): PVC, 32; o-NPOE, 64.5; BMPMP, 2 and NaTPB, 1.5. The potentiometric response of Hg2+-SE towards Hg2+ ion was linear in the wide range of concentrations (9.33 × 10-8-3.98 × 10-3 molL-1), while, the limit of detection of the proposed electrode was 3.98 × 10-8 molL-1 (8.00 μg L-1). The Hg2+-SE responds quickly to Hg2+ ions as the response time of less than 10 s. On the other hand, the slope value obtained for the developed electrode was 29.74 ± 0.1 mV/decade in the pH range of 2.0-9.0 in good agreement with the Nernstian response (29.50 mV/decade). The Hg2+-SE has relatively less interference with other metal ions. The Hg2+-SE was used as an indicator electrode in potentiometric titrations to estimate Hg2+ ions in waters, compact fluorescent lamp, and dental amalgam alloy and the accuracy of the developed electrode was compared with ICP-OES measurement values. Moreover, the new Schiff base (BMPMP) was synthesized and characterized using ATR-FTIR, elemental analysis, 1H NMR, and 13C NMR. The PVC membranes containing BMPMP as an ionophore unloaded and loaded with Hg(II) are reported by scanning electron microscope images (SEM) along with energy-dispersive X-ray spectroscopy (EDX) spectra.

Determination of Total Mercury in Solid Samples by Anodic Stripping Voltammetry

The anodic stripping voltammetry (ASV) was investigated to determine total mercury in solid samples using a gold electrode. The mercury was deposited on the gold electrode in a preconcentration step. The oxidation peak of mercury was irreversible. The optimal conditions of the procedure were found to be as follows: 0.05 mol L−1 HCl solution, deposition potential −0.5 V vs. Ag/AgCl/KCls, deposition time 40 s, and sweep rate 0.04 V s−1. Under the optimal conditions, the peak current showed a linear dependence on Hg2+ concentration in the range from 0.01 to 0.1 mg l−1. The detection limit and quantification limit were 4.28 µg L−1 and 12.98 µg L−1, respectively. The mean recovery and relative standard deviation were 91.2% and 2.4% (n = 9). The procedure was successfully applied for determining total mercury in samples collected from Hanoi light bulb warehouse—The Rang Dong Light Source and Vacuum Flask JSC. The results were compared with cold vapor atomic absorption spectrometry (CV-AAS).