Determination Of Mercury Ions Research Articles

Nitrogen and Sulfur Co-doped Carbon Dots for Ratiometric Fluorometric Determination of Mercury Ions.

Nitrogen and sulfur co-doped carbon dots (N, S-CDs) were prepared for dual-channel ratiometric fluorescence determination of mercury ions (Hg2+). The dual-emission N, S-CDs were synthesized using a simple one-pot hydrothermal treatment. When excited with visible light, N,S-CDs exhibited two emission peaks at 390 and 500nm. Notably, the presence of Hg2+ caused a considerable decrease in the fluorescence of N, S-CDs at 500nm, mainly due to the static quenching effect. In comparison, the fluorescence at 390nm was almost unchanged. With a limit of detection (LOD) of 0.21 µM for Hg2+, the N, S-CDs were successfully applied to the unlabeled ratiometric fluorescence determination of Hg2+ in actual water samples with good recoveries (94.5-107.8%). In conclusion, this developed ratiometric fluorescent sensor provides a reliable, environmentally friendly, rapid, and efficient platform for detecting Hg2+ in environmental applications.

Fabrication of a Microfluidic-Based Device Coated with Polyelectrolyte-Capped Titanium Dioxide to Couple High-Performance Liquid Chromatography with Inductively Coupled Plasma Mass Spectrometry for Mercury Speciation.

Mercury (Hg) is a toxic element which impacts on biological systems and ecosystems. Because the toxicity of Hg species is highly dependent on their concentration levels and chemical forms, the sensitive identification of the chemical forms of Hg-i.e., Hg speciation-is of major significance in providing meaningful information about the sources of Hg exposure. In this study, a microfluidic-based device made of high-clarity poly(methyl methacrylate) (PMMA) was fabricated. Then, titanium dioxide nanoparticles (nano-TiO2s) were attached to the treated channel's interior with the aid of poly(diallyldimethylammonium chloride) (PDADMAC). After coupling the nano-TiO2-coated microfluidic-based photocatalyst-assisted reduction device (the nano-TiO2-coated microfluidic-based PCARD) with high-performance liquid chromatography (HPLC) and inductively coupled plasma mass spectrometry (ICP-MS), a selective and sensitive, hyphenated system for Hg speciation was established. Validation procedures demonstrated that the method could be satisfactorily applied to the determination of mercury ions (Hg2+) and methylmercury ions (CH3Hg+) in both human urine and water samples. Remarkably, the zeta potential measured clearly indicated that the PDADMAC-capped nano-TiO2s with a predominance of positive charges indeed provided a steady force for firm attachment to the negatively charged device channel. The cause of the durability of the nano-TiO2-coated microfluidic-based PCARD was clarified thus.

The fabrication of a hybrid fluorescent nanosensing system and its practical applications via film kits for the selective determination of mercury ions

Heavy metal ions especially mercury exposure have severe toxic effects on living organisms and human health. Therefore, easy, accessible, and accurate determination strategies for the selective specification of mercury ions are essential for numerous disciplines. In the presented paper, new hybrid fluorescent iron oxide nanoparticles labeled with carbazole and triazole units (CT-IONP) were prepared via surface modification for the spectrofluorimetric determination of Hg2+ in environmental samples. The structure of the new sensing system is characterized via various spectroscopic, thermal, and microscopic techniques. Under optimized conditions, the hybrid system is not only used in fully water media but also highly fluorescent which led to the “turn-off” response towards Hg2+ ion in the presence of various competitive species. The presented sensing system was successfully used for the determination of Hg2+ ions in the wide linear working range (0.02–10.00 µmol.L−1) at nanomolar levels, where the limit of detection and quantification were calculated as 7.38 and 22.14 nmol.L−1. Importantly, the practical application of hybrid material was applied by CT-IONP embedded polycaprolactone (PCL) polymer film kits. The bluish color of fabricated film kits was instantly and dramatically turned colorless-dark patterns after the addition of Hg2+ ions, which resulted in convenient and rapid film test kits for selective detection.

Metal organic framework-derived CuO/Cu2O polyhedron-CdS quantum dots double Z-scheme heterostructure for cathodic photoelectrochemical detection of Hg2+ in food and environment

This study employed an innovative copper oxide/cuprous oxide (CuO/Cu2O) polyhedron‑cadmium sulphide quantum dots (CdS QDs) double Z-scheme heterostructure as a matrix for the cathodic PEC determination of mercury ions (Hg2+). First, the CuO/Cu2O polyhedral composite was prepared by calcining a copper-based metal organic framework (Cu-MOF). Subsequently, the amino-modified CuO/Cu2O was integrated with mercaptopropionic acid (MPA)-capped CdS QDs to form a CuO/Cu2O polyhedron-CdS QDs double Z-scheme heterostructure, producing a strong cathodic photocurrent. Importantly, this heterostructure exhibited a specifically reduced photocurrent for Hg2+ when using CdS QDs as Hg2+-recognition probe. This was attributed to the extreme destruction of the double Z-scheme heterostructure and the in situ formation of the CuO/Cu2O-CdS/HgS heterostructure. Besides, p-type HgS competed with the matrix for electron acceptors, further decreasing the photocurrent. Consequently, Hg2+ was sensitively assayed, with a low detection limit (0.11 pM). The as-prepared PEC sensor was also used to analyse Hg2+ in food and the environment.

Naphthalimide-based fluorescent probe for Hg2+ detection and imaging in living cells and zebrafish.

A simple naphthalimide-based fluorescent probe was designed and synthesized for the determination of mercury ion (Hg2+ ). The probe showed a noticeable fluorescence quenching response for Hg2+ . When added with Hg2+ , the fluorescence intensity of the probe at 560 nm was remarkably decreased with the color changed from yellow to colorless under ultraviolet (UV) light. The probe had a notable selectivity and sensitivity for Hg2+ and displayed an excellent sensing performance when detecting Hg2+ at low concentration (19.5nM). The binding phenomenon between the probe and Hg2+ was identified by Job's method and high-resolution mass spectrometry (HRMS). Moreover, the probe was not only utilized to identify Hg2+ in real samples with satisfactory results (92.00%-110.00%) but also was successfully used for bioimaging in cells and zebrafish. The recognition mechanism has been verified by transmission electron microscopy (TEM) for the first time. All the results showed that the probe could be used as a potent useful tool for detection of Hg2+ .

Ecofriendly ratiometric colorimetric determination of mercury(II) ion in environmental water samples using gallic acid-capped gold nanoparticles

Today, the monitoring and determination of heavy metal pollutants in the environment is an essential requirement for the environmental and research communities. Mercury ion is one of the most hazardous heavy metals, and scientists are trying to develop new methods for its detection. In this study, a new colorimetric sensor based on aggregation gallic acid-capped gold nanoparticles (GA-AuNPs) for the determination of mercury ions in environmental water samples was presented. The green synthesized GA-AuNPs exhibited a sharp surface plasmon resonance peak at 515 nm. The addition of mercury ions changed the surface properties of GA-AuNPs, resulting in the formation of a new peak near 670 nm due to the aggregation of GA-AuNPs, and an obvious color change from red to purple occurred. Thus, mercury ions were detected based on the change in the absorbance ratio (A670/A515). The developed sensor can determine the mercury ions in the concentration range of 78.0 nM to 8.3 µM with a detection limit of 5.5 nM. Based on the Environmental Protection Agency (EPA) and the World Health Organization (WHO) reports, the amount of Hg2+ ions in fresh water should be between 10.0 and 30.0 nM. The results indicate that the developed sensor can detect and determine trace amounts of Hg2+ ions in environmental water samples.

Electrochemical determination of mercury ions in various environmental samples using glassy carbon electrode modified with poly (L-tyrosinamide)

Electrochemical determination of mercury ions in various environmental samples using glassy carbon electrode modified with poly (L-tyrosinamide)

Electrochemical determination of mercury ions in different food samples using glassy carbon electrode modified with poly (crocin)

In this study, a glassy carbon electrode (GCE) modified with poly (crocin) (GCE/PCro) was designed for Hg2+ detection through the differential pulse anodic stripping voltammetry (DPASV) technique as a novel electrochemical sensor. Herein, differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and field emission-scanning electron microscopy (FE-SEM) were carried out to characterize the electrodes. Under optimal conditions, the linear range for Hg2+ was obtained at 0.1 to 300 pM and 300 to 2000 pM and, also, the limit of detection (LOD) (S/N = 3) was achieved at 0.033 pM. The prepared sensor was found to exhibit the qualities of selectivity, stability, repeatability, and reproducibility ability. To demonstrate the introduced sensor ability for real application, the modified electrode was employed to measure Hg2+ in tea, shrimp, and fish samples with a good recovery ranging from 98.50 to 103.02 – depicting that the modified electrode possesses satisfactory practicability to detect Hg2+.

Fabrication of glass-based analytical devices by immobilizing nanomaterials on glass substrate with a fluorescent glue for the highly sensitive determination of mercury ions

Fabrication of glass-based analytical devices by immobilizing nanomaterials on glass substrate with a fluorescent glue for the highly sensitive determination of mercury ions

Paper-based colorimetric sensor for mercury ion detection using smartphone digital imaging

In this research, we have developed a colorimetric paper-based sensing platform for the determination of mercury ion (Hg2+) using gold nanoparticles (AuNPs). To evaluate the selectivity in the response to a special target, urea is used as recognizing ligands on AuNPs for selective sensing Hg2+. Colorimetric readings in the presence of various environmentally relevant metal ions, such as Na+, K+, Zn2+, Pb2+, and Hg2+, were also studied. The results show that amongst all the tested metal ions, the SPR peaks are located at 525 nm except in the case of the present of Hg2+, in which is red shifted to 537 nm. Furthermore, a new broad peak is observed at the wavelength of 695 nm corresponding to the color change from red to purple. The relations of the ratios of maximum absorbance at 695 nm and 537 nm, and the concentration of Hg2+ illustrate the linear behavior with the sensitivity of 2.0 × 10-5 nM-1 and the detection limit of 30 nM. The modified AuNPs with urea are applied on the paper-based device for quantitative Hg2+ detection with smartphone digital imaging. The intensity ratios between blue and red colors are linear-dependence relations which can be used to determine the concentration of Hg2+.

Novel Amperometric Mercury-Selective Sensor Based on Organic Chelator Ionophore

A novel amperometric sensor for the direct determination of toxic mercury ions, Hg2+, based on the organic chelator ionophore N, N di (2-hydroxy-5-[(4-nitrophenyl)diazenyl]benzaldehyde) benzene-1,2-diamine (NDBD), and multiwalled carbon nanotubes (MWCNT) immobilized on a glassy carbon electrode surface was developed. The parameters influencing sensor performance including the ionophore concentration, the applied potential, and electrolyte pH were optimized. The sensor response to Hg2+ was linear between 1-25 µM with a limit of detection of 60 nM. Interferences from other heavy metal ions were evaluated and the sensor showed excellent selectivity towards Hg2+. The method was successfully applied to the determination of mercury ions in milk and water samples.

Highly fluorescent hydroxyl groups functionalized graphitic carbon nitride for ultrasensitive and selective determination of mercury ions in water and fish samples

Heavy metal ion pollution is always a serious problem worldwide. Therefore, monitoring heavy metal ions in environmental water is a crucial and difficult step to ensure the safety of people and the environment. A mercury ion (Hg2+) fluorescence probe with excellent sensitivity and selectivity is described here. The functionalized graphitic carbon nitride nanosheets (T/G-C3N4) fluorescence probe was fabricated using melamine as a precursor by the pyrolysis technique, followed by a rapid KOH heat treatment method for 2 min. The chemical structure and morphology of the T/G-C3N4 probe were characterized using multiple analytical techniques including UV–Vis, SEM, XPS, XRD, and fluorometer spectroscopy. Geometry optimization of T/G-C3N4 as a modified probe was performed to assess its stability and interaction ability with Hg(II) via using the density function approach. The T/G-C3N4 probe showed a linear response based on quenching over the range 0–1.25 × 103 nM Hg(II); the detection limit was 27 nM. The remarkable sensitivity of T/G-C3N4 towards the Hg2+ ions was explained by the intense coordination and fast chelation kinetics of Hg2+ with the NH2, CN, C=N, and OH groups of T/G-C3N4 nanoprobe. The T/G-C3N4 probe demonstrates exceptional selectivity for Hg2+ ions among other metal ions including (Na+, Ag+, Mg2+, Fe2+, Fe3+, Co2+, Ni2+, Cd2+, K+, Ca2+, Cu2+, Pb2+, Mn2+ and Hg2+) and over a broad pH range (6–10), together with remarkable long-term fluorescence stability in water (> 30 days) and minimal toxicity. T/G-C3N4 was used to detect and quantify Hg2+ ions in tuna and mackerel fish and the results compared to ICP-AES. The results obtained offer a new simple and green technique for the design of multifunctional fluorescent probe appropriate for environmental applications.Graphical

Self-reduce gold nanoparticles on Ti3C2Tx MXene nanoribbons to highly sensitive colorimetric determination of mercury ion and cysteine based on the mercury-motivated peroxidase mimetic activity

Ti3C2Tx MXene is the rising-star material recently and can exhibit unique self-reduction/adsorption ability towards some noble metal ions. Herein, Ti3C2Tx MXene nanoribbons (Ti3C2TxNR) decorated with gold nanoparticles (AuNPs) (Ti3C2TxNR@AuNPs nanohybrids) are prepared through a simple self-reduction method and used as a novel nanozyme for constructing a highly sensitive colorimetric sensing platform of mercury ion (Hg2+) on the basic of the mercury-motivated peroxidase mimetic activity: the peroxidase mimetic activity of Ti3C2TxNR@AuNPs towards 3,3′,5,5′- tetramethylbenzidine (TMB) is motivated and improved dramatically in the presence of Hg2+, inducing TMB to be oxidized and the solution color from colorless to dark blue that can be monitored. In addition, since the cysteine (Cys) molecules have the reducing property, which can reduce the TMB oxide (oxTMB) and further recover the color to colorless, a colorimetric sensing platform for Cys is also established. After optimizing several key parameters, the developed Ti3C2TxNR@AuNPs nanozyme-based colorimetric sensing platform exhibits superior sensing performances towards Hg2+ and Cys; meanwhile, the colorimetric detection of both analytes can also be achieved successfully by a smartphone. This work is expected to provide a simple approach to prepare MXene-based metal nanozyme and construct highly sensitive colorimetric sensing platform for Hg2+ and Cys.

Spectrophotometric determination of Mercury(II) ions in laboratory and Zamzam water using bis Schiff base ligand based on 1,2,4-Triazole-3,5-diamine and o-Vaniline

The current study presents the development of a simple and direct spectrophotometric approach for Hg(II) ions determination. This method has the significant advantage of being a simple procedure where no further solvent purification or pre-concentration is needed. The concentration of Hg(II) ions was determined in the presence of the Schiff base ligand named 2-((5-(2-hydroxy-3-methoxybenzylideneamino)–2H-1,2,4-triazole-3-ylimino)methyl)-6-methoxyphenol (HMBT), at pH 10 using Briton Robinson Buffer. The method Obey Beer's law in concentration range 0.1–6 µg mL- 1 of Hg with (LOD) 0 0.016 µg L -1 and (LOQ) 0.051 µg/L. The molar ratio ensured the formation of a metal complex between HMBT and Hg ions was in the molar ratio 2:1 (HMBT: Hg2+). The method was used for the determination of mercury ions in tap water and Zamzam water samples. The applied method has many advantages, such as simplicity, low cost, ease of operation, rapid detection, low-ligand consumption, and high sensitivity. The analytical method sensitivity was confirmed via the suitable selection of experimental circumstances. More information about the structure and stoichiometry of the complex formed in solution between Hg(II) and HMBT ligand has been gained through the isolation and investigation of solid complex (HMBT-Hg). The structure of the solid complex, HMBT-Hg, has been elucidated by applying analytical routes such as elemental analysis and the spectral mass, UV–vis spectra, and thermal analysis.

Rapid Determination of Mercury Ions in Environmental Water Based on an N-Rich Covalent Organic Framework Potential Sensor

In this article, an N-rich covalent organic framework (COFTFPB-TZT) was successfully synthesized using 4,4′,4′-(1,3,5-triazine-2,4,6-triyl) trianiline (TZT), and 4-[3,5-bis (4-formyl-phenyl) phenyl] benzaldehyde (TFPB). The as-prepared COFTFPB-TZT possesses irregular cotton wool patches with a large specific surface area. A novel selective electrode based on COFTFPB-TZT was used for the determination of Mercury ions. The abundance of N atoms in COFTFPB-TZT provides more coordination sites for Hg2+ adsorption, resulting in a change in the surface membrane potential of the electrode to selectively recognize Hg2+. Under optimal experimental conditions, the ion-selective electrode shows a good potential response to Hg2+, with a linear range of 1.0 × 10−9∼1.0 × 10−4, a Nernst response slope of 30.32 ± 0.2 mV/-PC at 25°C and a detection limit of 4.5 pM. At the same time, the mercury-ion electrode shows a fast response time of 10 s and good reproducibility and stability. The selectivity coefficients for Fe2+, Zn2+, As3+, Cr6+, Cu2+, Cr3+, Al3+, Pb2+, NH4+, Ag+, Ba2+, Mg2+, Na+, and K+ are found to be small, indicating no interference in the detection system. The proposed method can be successfully applied to the determination of Hg2+ in 3 typical environmental water samples, with a recovery rate of 98.6–101.8%. In comparison with the spectrophotometric method utilizing dithizone, the proposed method is simple and fast and holds great potential application prospects in environmental water quality monitoring and other fields.

Vertically-Ordered Mesoporous Silica Films for Electrochemical Detection of Hg(II) Ion in Pharmaceuticals and Soil Samples.

Rapid and simple determination of mercury ion (Hg2+) in pharmaceuticals and soil samples is vital for human health and the environmental monitoring. Vertically-ordered mesoporous silica films (VMSF) supported by the indium tin oxide (ITO) electrode surface were prepared by electrochemically assisted self-assembly method and utilized for electrochemical detection of Hg2+. Owing to the negatively charged channel walls and ultrasmall pore diameter, VMSF displays obvious cationic selectivity and has highly electrostatic interaction for Hg2+, giving rise to the strong electrochemical signals. By recording the anodic stripping signals of adsorbed Hg2+ using differential pulse voltammetry, quantitative detection of Hg2+ was achieved with a wide linear range (0.2 μM–20 μM) and a low limit of detection (3 nM). Furthermore, considering the anti-fouling and anti-interference capacity of VMSF, the proposed VMSF/ITO sensor has been successfully applied to detect Hg2+ in pharmaceuticals and soil samples without tedious pretreatment processes of samples.

A simple label-free electrochemical aptamer sensor for detection of Hg2+ based on black phosphorus

In this work, a simple label-free aptamer-based electrochemical sensor was developed for determination of mercury ions (Hg2+) by polylysine (PLL) modified black phosphorus nanosheets (BP) and gold nanoparticles (AuNPs) as signal amplification strategy. The PLL-BP composite materials greatly improved electron transfer speed and electrochemical behavior of electrode in the detection of analytes. AuNPs can amplify the electrochemical signal and facilitate the binding of aptamers to the electrode. The selected aptamer (Apt) can bind specifically to Hg2+ to form a T-Hg2+-T structure, which we used to detect Hg2+. Experimental results showed that the prepared electrochemical aptamer sensor exhibited wide linear range from 1.0–500 nM, along with a low detection limit of 0.14 nM. Moreover, the electrochemical aptamer sensor has good specificity, stability, and repeatability. Therefore, this proposed electrochemical aptamer sensor provide a simple and sensitive method for the detection of Hg2+, which is expected to be used for the detection of trace amounts of Hg2+ in actual samples.

Potentiometric Determination of Mercury Ions by Sol-gel Synthesized Multi-walled Carbon Nanotubes Zr (IV) Phosphate Composite Fabricated Membrane Electrode

Background: The nanocomposites are formed by introducing inorganic nano-clusters, fullerenes, clays, metals, oxides with numerous organic polymers. The assembly of these materials exhibits better properties such as catalytic, thermal stability and adsorption properties, etc. than the individual materials. Objective: The nanocomposite synthesized here by sol-gel method was primarily evaluated for cation exchange properties viz, elution concentration, elution behavior, effect of temperature on ion-exchange capacity. The synthesized composite was used as an electro-active component for fabrication of Hg2+ ion selective membrane electrode. Method : The sol-gel technique was used to synthesize multi-walled carbon nanotubes Zr(IV) phosphate composite cation exchanger. By the technique of solution casting the material as an electroactive part was used for the fabrication of mercury ion-selective membrane electrode. The potential response of the electrode was also investigated as a function of membrane composition and plasticizer. Results: The composite cation exchanger exhibited 1.8 meq g-1 ion-exchange capacity (IEC). It retained almost 65 % of its initial IEC upto a temperature of 400 °C. Distribution studies showed the selective nature of the composite for Hg(II) ions. The ion-selective membrane electrode exhibited typical Nernstian response towards Hg2+ ions in the concentration range 1×10-1 -1×10-7 M. Conclusion: The results discussed reveal that a new cation composite exchanger-multi-walled carbon nanotubes Zr (IV) phosphate exhibited excellent cation exchange properties and was found to be preferentially selective towards the Hg2+ ions. It was also used as an indicator electrode in the titration of Hg2+ using ethylenediaminetetraacetic acid as a titrant.

A New Reusable Mercury-Sensitive Turn-On Nano-Chemosensor Based on Functionalized CoFe2O4@SiO2 Magnetic Nanocomposite

A novel turn-on nano chemosensor for Hg2+ was developed based on CoFe2O4@SiO2 nanocomposite. Cobalt nano ferrite particles were decorated with 1,8-naphthalimide dye conjugated with rhodamine dye. It was characterized using X-ray powder diffraction (XRD), transmission electron microscopy (TEM), FT-IR techniques. A fluorescence enhancement was observed upon binding Hg2+ to two core chromogenic dyes. No significant change in the fluorescence intensity was observed in the presence of other metal ions. The results showed that the functionalized nanocomposite CoFe2O4@SiO2/NR exhibited selective 'turn-on' fluorescent enhancements with Hg2+. Also, the company of magnetic CoFe2O4@SiO2 nanocomposite (with a wide range of applications such as biomedicine, magnetic fluids, magnetic energy storage) and catalysis facilitates the magnetic separation of the Hg (II) from the solution. Nano chemosensor exhibits high selectivity, high sensitivity and fast response to trace mercury ions. Designed nanosensor successfully applied for Hg2+determination at real samples with a linear range of 0.04-0.76 μM of Hg2+ ions. It was successfully applied for the determination of mercury ion in real samples of tap water. It seems that the presence sensor is a suitable candidate for the detection of trace mercury ion in biomedical samples like a human serum. Also, it is fast and easy control for monitoring of water toxicity of pollutant industries.

A LATERAL FLOW TEST SYSTEM FOR THE SENSITIVE DETERMINATION OF MERCURY IONS IN WATER BODIES

A lateral flow test system has been implemented and the conditions for the sensitive and selective determination of mercury ions in the matrix of natural waters have been optimized. A linear range for mercury ions concentration from 0.3 to 25 ng/ml and limit of detection of 0.13 ng/mL were achieved, which meets the practical requirements for drinking water.