Electrochemical Detection Of Hg Research Articles

Smartphone-assisted dual-channel discriminative detection of Hg(II) and Cu(II) ions with a simple, unique, readily available probe

Heavy metal ions are well-known atmospheric and environmental pollutants and cause long-term damage to humans. Mercury is one of the most toxic and hazardous one that induce critical motor disorders and a variety of diseases. Likewise, excess copper can lead to Alzheimer’s and Parkinson’s disease, as well as various other health conditions. Therefore, selective and sensitive methods for determining and visualizing mercury and copper remain necessary. In our study, we developed the first-ever optical-electrochemical method of discriminatively detecting Hg2+ and Cu2+ ions using 1-thioglycerol (TG)-modified gold nanoparticles (AuNPs) and by altering the solution’s medium. Adding Hg2+ ions to AuNP–TG in ultrapure water changed the original burgundy color blue, the initial absorbance value (i.e., 520 nm) decreased, and a new absorbance peak appeared at λmax = 670 nm. In a phosphate-buffered solution, Cu2+ ions issued a similar response. However, neither Hg2+ nor Cu2+ ions exhibited cross-reactivity under those sensing conditions. The optical mechanism for detecting both metal ions seems to have relied on the destabilization and aggregation of AuNPs. On the one hand, the electrochemical detection of Cu2+ stemmed from the reduction of the complex between Cu2+ and TG’s neighboring hydroxyl groups in the probe, whereas the electrochemical detection of Hg2+ stemmed from the fact that Hg2+ broke the AuNP–S bond, after which the AuNPs clustered and significantly increased the electrode’s electron transfer rate. Last, because the method involves using a smartphone to read signals without requiring professional equipment, it considerably decreases the cost of detection and shows promise for the rapid on-site detection of Hg2+ and Cu2+ ions.

Using the Photo-Excited Barrier Effect to Improve Electrochemical Detection of Hg2+

Using the Photo-Excited Barrier Effect to Improve Electrochemical Detection of Hg2+

Sulfur-Doped Reduced Graphene Oxide@Chitosan Composite for the Label-Free Electrochemical Detection of Hg <sup>2+</sup> in Fish Muscle

Sulfur-Doped Reduced Graphene Oxide@Chitosan Composite for the Label-Free Electrochemical Detection of Hg <sup>2+</sup> in Fish Muscle

Red fluorescent and electrochemical detection of Hg2+ ions using perylene diimide dye: Analysis in soil, urine and water samples

Red (λem =620 nm) fluorescent and electrochemical detection of Hg2+ ions has been achieved in HEPES buffer/DMSO (9/1, v/v, pH = 7.4) using dimethylthiocarbamoyl (DMTC)-functionalized perylene diimide (PDI 2) dye. The self-assembly of PDI 2 showed formation of red-violet non-fluorescent aggregates having spherical microstructures at the interface in >50 % H2O/DMSO mixture supported by optical methods, dynamic light scattering (DLS) studies and atomic force microscopy. The aggregation induced emission (AIE) in PDI 2 transformed into aggregation induced quenching (ACQ) in >30 % H2O/DMSO. Linear correlation ranges for the detection of Hg2+ ions are 0–2 μM and 0–10 nM showed LOD of 8.1 nM and 7.4 nM by absorption and emission-based methods, respectively. The mechanism involves interaction of DMTC with Hg2+ ions however longer incubation time (>24 h) shows chemodosimeter mechanism wherein Hg2+ induced cleavage of DMTC moiety to release PDI-OH. These mechanisms have been supported by NMR/IR studies, model reaction and partially by electrochemical and DLS methods. PDI 2 has been applied for detection of Hg2+ in real water, soil and urine samples with excellent recovery.

Three-dimensional macroporous Carbon/Zr-2,5-dimercaptoterephthalic acid metal-organic frameworks nanocomposites for removal and detection of Hg(II)

Mercury ion (Hg(II)) has serious destructive effects on organisms and environments even at extremely low concentration. Therefore, effective removal and highly sensitive determination of trace Hg(II) is very important. Herein, mercaptan functionalized metal-organic frameworks (MOFs) were prepared by the coordination between Zr (IV) and 2,5-dimercaptoterephthalic acid (Zr-DMBD MOFs) and attached to three-dimensional kenaf stem-derived carbon (3D-KSC) to form a novel nanocomposite for removal and electrochemical detection of Hg(II). The sensitivity of Hg(II) detection was 324.58 μA μM−1 cm-2, the linear range was 0.25 μM–3.5 μM and the detection limit was 0.05 μM. The good performances were because lots of Zr-DMBD MOFs were uniformly dispersed on 3D-KSC and the porous Zr-DMBD MOFs had a large number of mercaptan groups to enrich Hg(II) significantly on the electrode. The Hg(II) detection would not be interfered by other co-existing heavy metal ions, and the Zr-DMBD MOFs/3D-KSC also showed excellent stability and reproducibility. Furthermore, the Zr-DMBD MOFs/3D-KSC could effectively remove Hg(II) in real wastewater. The residues were lower than national discharge standard of industrial wastewater (GB30770-2014).

Aniline-mediated synthesis of carboxymethyl cellulose protected silver nanoparticles modified electrode for the differential pulse anodic stripping voltammetry detection of mercury at trace level

Single-pot synthesis of carboxymethylcellulose-protected silver nanoparticles (CMC@AgNPs) was investigated using aniline as a reducing agent. Polymer matrix-embedded nanoparticles were synthesized by two different experimental conditions, namely under reflux and at room temperature. Similarly, a control experiment was carried out using polyvinylpyrrolidone as stabilizing agent under identical experimental conditions. Resulting AgNPs were isolated and characterized by UV–Vis, FT-IR, and SEM to identify shape, size, and type of capping action. CMC-capped AgNPs were octahedron-shaped whereas PVP-capped exhibited a core–shell kind of capping similar to a nested protection of AgNPs. The electrochemical property of the modified electrode was studied using electrochemical impedance spectroscopy and cyclic voltammetry. Electrochemical detection of Hg2+ was investigated using CMC@AgNPs/GCE with an enhanced peak current as noted by DPASV method. Detection limit was found to be 0.19 nM, and its linear ranges were between 5 and 75 μM based on signal-to-noise ratio (S/N = 3). The present system can be utilized for the determination of Hg2+ in water samples at low-concentration ranges.

Electrochemical Detection of Hg(II) in Environmental Water Samples Based on Multiwalled Carbon Nanotube–Reduced Graphene Oxide Hybrid Film

In this work, we describe the fabrication of an electrochemical sensor for the detection of Hg2+in various water samples. The electrochemical sensor is fabricated on an indium tin oxide (ITO) modified with multi–walled carbon nanotubes (MWCNT) and reduced graphene oxide (RGO) hybrid film. The MWCNT was firstly dispersed using graphene oxide (GO) as dispersant. After coating on the ITO, the GO was then electrochemically reduced to RGO. The obtained thin film was characterized by scanning electron microscope (SEM), FTIR, Raman spectroscopy and 3D optical surface profiler. Cyclic voltammetry and differential pulse voltammetry were employed to investigate the electrocatalytic performance towards the Hg2+ oxidation. Under optimum conditions, the proposed sensor showed a wider linear range at Hg(II) concentrations of 0.05–150 nM. The limit of detection was calculated to be 0.05 nM.

The preparation of a flexible AuNP modified carbon cloth electrode and its application in electrochemical detection of Hg(ii) by continuous flow in environmental water.

In this article, a carbon cloth composite electrode modified with gold nanoparticles (AuNPs) was prepared by a facile in situ electrodeposition method and applied to the detection of mercury ions in water. With the optimized electrochemical detection conditions and methods, the limit of detection (LOD) was 0.6 μg L-1 with the linearity ranging from 2 to 200 μg L-1 by the SWSV detection method, and the electrode showed good repeatability after many cycles. Based on this detection method, a continuous flow electrochemical detection system was constructed and applied to the detection of Hg ions in environmental water samples. The standard addition experimental results of two real water samples with an addition level of 10 and 50 μg L-1 showed that the recoveries were between 92.4% and 108.9% with RSDs from 2.01% to 3.22%. These results showed the same performance as that of the ZAAS mercury detection method (recovery: 94-102.4%, RSD 2.09-5.4%). Compared with other electrode materials, a shorter detection time, a wider linear range and high stability with a similar LOD can be achieved by a continuous flow detection method by using the composite electrode. The established continuous flow electrochemical detection system would have promising application in online and real-time detection of heavy metals in environmental water.

Electrochemical detection of Hg(II) in water using self-assembled single walled carbon nanotube-poly(m-amino benzene sulfonic acid) on gold electrode

This work reports on the detection of mercury using single walled carbon nanotube-poly (m-amino benzene sulfonic acid) (SWCNT-PABS) modified gold electrode by self-assembled monolayers (SAMs) technique. A thiol containing moiety (dimethyl amino ethane thiol (DMAET)) was used to facilitate the assembly of the SWCNT-PABS molecules onto the Au electrode surface. The successfully assembled monolayers were characterised using atomic force microscopy (AFM). Cyclic voltammetric and electrochemical impedance spectroscopic studies of the modified electrode (Au-DMAET-(SWCNT-PABS)) showed improved electron transfer over the bare Au electrode and the Au-DMAET in [Fe (CN)6]3−/4− solution. The Au-DMAET-(SWCNT-PABS) was used for the detection of Hg in water by square wave anodic stripping voltammetry (SWASV) analysis at the following optimized conditions: deposition potential of −0.1V, deposition time of 30s, 0.1M HCl electrolyte and pH3. The sensor showed a good sensitivity and a limit of detection of 0.06μM with a linear concentration range of 20ppb to 250ppb under the optimum conditions. The analytical applicability of the proposed method with the sensor electrode was tested with real water sample and the method was validated with inductively coupled plasma – optical emission spectroscopy.

Electrochemical detection of Hg(II) ions based on nanoporous gold nanoparticles modified indium tin oxide electrode

Nanoporous gold nanoparticles (np-Au NPs), dispersed on the indium tin oxide film coated glass, were firstly employed to fabricate Hg(II) sensing platform in differential pulse anodic stripping voltammetry (DPASV). The np-Au NPs integrated the features of highly porous nanoparticles and the high affinity of gold nanomaterials for mercury, which endowed the sensing platform with high sensitivity and good reproducibility. Following optimization of the method, a calibration curve from 0.1 to 10μg/L Hg(II) was obtained in HCl solution. The detection limit was 0.03μg/L (0.15nM) at a signal-to noise ratio of 3. The interference from other heavy metal ions associated with Hg(II) detection could be effectively avoided. The performance of the proposed electrode was also applied in the detection of trace Hg(II) in different real samples with satisfactory results.

An electrochemical detection of Hg2 + ion using graphene oxide as an electrochemically active indicator

An electrochemical Hg2+ ion sensor was developed in which graphene oxide (GO) was employed as an indicator for electrochemical signal generation. The Gold surface modified with thiol-functionalized poly-T-oligonucleotides was exposed to an Hg2+ ion solution. It is because Hg2+ ions are inserted between T–T mismatched base pairs to form a T–Hg2+–T bond, the structure of the DNA transitioned from a single-stranded to a double-stranded form. The surface was exposed to an aqueous solution of GO for immobilizing GO on the surface. The current required for the electrochemical reduction of GO was monitored on the resulting surface, which exhibited a linear response over a 1–300nM range of Hg2+ ion concentrations and a high selectivity toward Hg2+ ion.

Electropolymerized surface ion imprinting films on a gold nanoparticles/single-wall carbon nanotube nanohybrids modified glassy carbon electrode for electrochemical detection of trace mercury(II) in water

Electrochemical detection of Hg(II) using a electropolymerized ion imprinting poly(2-mercaptobenzothiazole) films at the surface of gold nanoparticles/single-walled carbon nanotube nanohybrids modified glassy carbon electrode (PMBT/AuNPs/SWCNTs/GCE) is described for the first time. The Hg(II)-imprinted PMBT/AuNPs/SWCNTs/GCE sensor exhibits larger binding to functionalized capacity, larger affinity, faster binding kinetics and higher selectivity to template Hg(II). The differential pulse anodic stripping voltammetry (DPASV) response of the Hg(II)-imprinted PMBT/AuNPs/SWCNTs/GCE sensor to Hg(II) is ca. 3.7- and 10.5-fold higher than that at the non-imprinted PMBT/AuNPs/SWCNTs/GCE and the imprinted PMBT/AuNPs/GCE, respectively, and the detection limit for Hg(II) is 0.08nM (S/N=3, which is well below the guideline value given by the World Health Organization) and a sensitivity of 0.749μAnM−1 was obtained. Excellent wide linear range (0.4–96.0nM) and good repeatability (relative standard deviation of 2.6%) were obtained for Hg(II). The interference experiments show that Ag(I), Pb(II), Cd(II), Zn(II) and Cu(II) had little or no influence on the Hg(II) signal. These values, particularly the high sensitivity and excellent selectivity in contrast to the values reported previously in the area of electrochemical Hg(II) detection, demonstrate the analytical performance of the Hg(II)-imprinted PMBT/AuNPs/SWCNTs/GCE toward Hg(II) is superior to the existing electrodes and could be used for efficient determination of Hg(II) in natural water samples.