Detection Of Mercury Research Articles

Biosynthesis of Silver Nanoparticles from Kepundung Fruit Peel (Baccauera Racemose) and Their Application in Mercury Detection Using Digital Image Colorimetric Methods

Biosynthesis of Silver Nanoparticles from Kepundung Fruit Peel (Baccauera Racemose) and Their Application in Mercury Detection Using Digital Image Colorimetric Methods

Identification of medium- and mechanism-related pitfalls towards improved performance and applicability of electrochemical mercury(II) aptasensors.

The importance of understanding the mercury (II) ion interactions with thymine-rich DNA sequences is the reason for multiple comparative investigations carried out with the use of optical detection techniques directly in the depth of solution. However, the results of such investigations have limited applicability in the interpretation of the Hg2+ binding phenomenon by DNA sequences in thin, interfacial (electrode/solution), self-organized monolayers immobilized on polarizable surfaces, often used forsensing purposes in electrochemical biosensors. Overlooking the careful optimization of the measurement conditions is the source of discrepancies in the interpretation of the registered electrochemical signal. In this study, the chosen effects accompanying the efficiency of surface related recognition of Hg2+ by polyThymine DNA sequences labelled with methylene blue were investigated by voltammetry, QCM and spectro-electrochemical techniques. As was shown, the composition of the biosensing layer and buffers or the analytical procedures have a significant impact on the registered electrochemical readout which translates into signal stability, the biosensor's working parameters or even the mechanism of detection. After elucidation of the above factors, the complete and ready-to-use biosensor-based analytical solution was proposed offering subpicomolar mercury ion determination with high selectivity (also in aqueous real samples), reusability, and high signal stability even after long-term storage. The developed procedures were successfully used during the miniaturization process with self-prepared (PVD) elastic transducers. The obtained sensor, together with the simplicity of its use, low manufacturing cost, and attractive analytical parameters (i.e., LOD < < Hg2+ WHO limit) can present an interesting alternative for on-site mercury ion detection in environmental samples.

Parthenium hysterophorus derived nanostructures as an efficient carbocatalyst for the electrochemical sensing of mercury(II) ions

The sustainable utilization of resources motivate us to create eco-friendly processes for synthesizing novel carbon nanomaterials from waste biomass by minimizing chemical usage and reducing energy demands. By keeping sustainability as a prime focus in the present work, we have made the effective management of Parthenium weeds by converting them into carbon-based nanomaterial through hydrothermal treatment followed by heating in a tube furnace under the nitrogen atmosphere. The XPS studies confirm the natural presence of nitrogen and oxygen-containing functional groups in the biomass-derived carbon. The nanostructure has adopted a layered two-dimensional structure, clearly indicated through HRTEM images. Further, the nanomaterials are analyzed for their ability towards the electrochemical detection of mercury, with a detection limit of 6.17 μM, while the limit of quantification and sensitivity was found to be 18.7 μM and 0.4723 μM μA−1 cm−2, respectively. The obtained two-dimensional architecture has increased the surface area, while the nitrogen and oxygen functional groups act as an active site for sensing the mercury ions. This study will open a new door for developing metal-free catalysts through a green and sustainable approach by recycling and utilization of waste biomass.

Improved mercury ions (Hg2+) detection by composite silver nanoparticles (AgNPs) and nitrogen - Sulfur co-doped carbon dots (N, S-CDs)

Heteroatom doping has been demonstrated as an efficient method to increase the fluorescence quantum yield efficiency of carbon dots. Co-doping with heteroatoms leads to additional active sites on carbon dots, both extending their use in sensing systems and improving the sensitivity of detection. In this study, the synthesis of nitrogen and sulfur co-doped carbon dots (N, S-CDs) through a single step hydrothermal process was reported, utilizing citric acid and thiourea as sources of carbon, nitrogen, respectively. This N, S-CDs was composited with silver nanoparticles (AgNPs) to detect mercury ions (Hg2+) with reabsorption principle. The fluorescence intensity of the carbon dots was vanished by AgNPs due to the reabsorption effect due to overlap between emission spectrum of N, S-CDs and absorption spectrum of AgNPs, and it is recovered by the addition of Hg2+ due to formation Ag/Hg amalgam. As a result, composite of N, S-CDs-AgNPs can be used as a fluorescence "turn-on" probe for rapid and highly sensitive detection of Hg2+. The lowest limit of detection (LOD) of Hg2+ is 10 nM with linear detection in the range of 1 nM - 1.0 μM. This LOD is improved three-order of magnitude as compared to the N, S-CDs only with detection limit in 10 μM. This result proves that the composite of N, S–CDs-AgNPs is a very sensitive fluorescence probe for mercury ions detection. This work will also provide ideas for creating and building novel fluorescence probes for similar applications.

Ion-Imprinted Polymer-Based Sensor for the Detection of Mercury Ions.

In this work, the development of a novel method for the detection of mercury (II) ions in wastewater using a mercury ion-imprinted polymer (IIP) combined with a quartz crystal microbalance (QCM) is described. The IIP was successfully synthesized via the polymerization of a of a novel fluorescein- and 2-aminophenol-functionalized methacrylic acid monomer, which was noted to have high binding affinity to mercury (II) ions. This polymer was subsequently coated on a QCM chip to create an IIP-QCM sensor. This sensor was established to have high selectivity and good sensitivity to mercury (II) ions, and had a limit of detection (LOD) of 14.17 ppb, a limit of quantification (LOQ) of 42.94 ppb, a signal-to-noise ratio (S/N) of 4.29, good repeatability, and a working range of 42.94 ppb to 2 ppm. The sensor was also able to analyze tap water and wastewater samples. The IIP-QCM is, therefore, promising as a highly selective, cost-effective, and rapid mercury ion sensor for applications involving the detection of mercury in wastewater.

Sulfur and nitrogen co-doped carbon quantum dots/polyurethane nanocomposite as a new fluorescent sensor for highly sensitive and selective detection of toxic mercury (II) ions

Sulfur and nitrogen co-doped carbon quantum dots/polyurethane nanocomposite as a new fluorescent sensor for highly sensitive and selective detection of toxic mercury (II) ions

Highly selective detection and removal of mercury ions in the aquatic environment based on magnetic ZIF-71 multifunctional composites with sufficient chlorine functional groups

The development of both detection and removal technologies for heavy metal ions is of great importance. Most of the existing adsorbents that contain oxygen, nitrogen or sulfur functional groups can remove heavy metals, but achieving both selective detection and removal of a single metal ion is difficult because they bind to a wide range of heavy metal ions. Herein, we selected zeolite imidazolium hydrochloride framework-71 (ZIF-71) with sufficient chlorine functional groups to fabricate magnetic ZIF-71 multifunctional composites (M-ZIF-71). M-ZIF-71 had a large specific surface area, excellent water stability, and good magnetic properties, which made M-ZIF-71 conducive to the separation and recovery of adsorbents and the assembly of electrodes. M-ZIF-71 exhibited high selectivity, wide linear range (1–500 μg/L), and low detection limit (0.32 μg/L) for electrochemical detection of mercury ions (Hg2+). Meanwhile, M-ZIF-71 demonstrated rapid Hg2+ adsorption with a high capacity of 571.2 mg/g and excellent recyclability. The high selectivity for Hg2+ was attributed to the powerful affinity of highly electronegative chlorine and Hg2+. Moreover, XPS spectra demonstrated the interaction between chlorine and Hg2+. This work provides a new inspiration for applications in the targeted monitoring and removal of heavy metal pollution.

Terbium Vanadate Nanowires-Based Electrochemical Sensors for Mercury Ions.

Terbium vanadate nanowires were synthesized via a facile chemical approach using sodium vanadate and terbium chloride. Morphology, structure, composition, and electrochemical characteristics of the terbium vanadate nanowires were investigated by different techniques. Terbium vanadate nanowires with single crystalline tetragonal TbVO4 phase possess smooth surface and flat tips. The length of the nanowires is longer than 5μm, and diameter is 40-100nm. Terbium vanadate nanowires modified electrode was used for trace-level mercury ions (Hg2+) detection. One well-defined stripping peak exists at - 0.34V at the terbium vanadate nanowires modified electrode in 0.1mM Hg2+ solution. Buffer solution pH value, deposition time, deposition potential, and standing time are pH = 1, 150s, - 1.5V, and 60s, respectively. Detection limit for Hg2+ detection is 0.18nM, and linear range is 0.01-100μM. The proposed terbium vanadate nanowires modified electrode exhibits significant selectivity, stability, and reproducibility toward Hg2+. The usefulness of the developed sensor based on the terbium vanadate nanowires modified electrode was verified by Hg2+ detection in real samples.

Smartphone-assisted ratiometric fluorescence sensor based on NS-codoped carbon dots/Au nanoclusters for rapid detection of Hg2+

Mercury metal can be absorbed into human body through the food chain, and cause considerable harm to human health. Herein, a novel smartphone-enabled ratiometric fluorescence sensing system, which was made up of nitrogen-sulfur co-doped carbon dots (NSCDs) and Au nanoclusters (AuNCs), had developed for rapid detection of mercury ion (Hg2+). The NSCDs/AuNCs displayed dual-emission fluorescence at 406/690 nm. After introducing Hg2+, the fluorescence at 690 nm was obviously quenched, while the signal around 406 nm was slightly attenuated, causing a color change from pink-purple to blue. Under the most suitable conditions, the ratiometric fluorescence probe had two linear ranges of 0.05–3.0 and 3.0–7.0 μM with a low limit of detection (LOD) of 18 nM. The approach was utilized to detect Hg2+ in real water samples. Furthermore, a portable smartphone-assisted sensing platform based on NSCDs/AuNCs provides a simple, affordable, and efficient method for monitoring Hg2+ in the environments and other fields.

BODIPY- imine based fluorescence “turn on” chemosensor for selective sensing of Hg2+

The detection of mercury has gained considerable attention due to its both environmental and biological impacts. In this study, a BODIPY- imine chemosensor (3) having an imine molecule at the meso position of the BODIPY core was synthesized, and its structure was characterized by spectroscopic and analytical methods as well as single crystal XRD. Chemosensor 3 showed a poor emission band in the DMSO/H2O (9:1 v/v) solvent system (ΦFl < 0.01). Upon the addition of Hg2+, the fluorescence intensity of 3 increased notably with a 0.031 ΦFl value, and the limit of detection for Hg2+ was calculated as 0.90 μM. The sensing mechanism of 3 was investigated 1H NMR titration studies and Hg2+ ion induced hydrolysis of the imine double bond and thus activating the PET OFF proccess. The BODIPY- imine compound (3) can be used as reaction-based fluorescence probe for the sensing of Hg2+ ion.

Quantified retrospective biomonitoring of fetal and infant elemental exposure using LA-ICP-MS analysis of deciduous dentin in three contrasting human cohorts.

Spatial elemental analysis of deciduous tooth dentin combined with odontochronological estimates can provide an early life (in utero to ~2 years of age) history of inorganic element exposure and status. To demonstrate the importance of data normalization to a certified reference material to enable between-study comparisons, using populations with assumed contrasting elemental exposures. We used laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) of dentin to derive a history of elemental composition from three distinct cohort studies: a present day rural cohort, (the New Hampshire Birth Cohort Study (NHBCS; N = 154)), an historical cohort from an urban area (1958-1970), (the St. Louis Baby Tooth Study (SLBT; N = 78)), and a present-day Nigerian cohort established to study maternal HIV transmission (Dental caries and its association with Oral Microbiomes and HIV in young children-Nigeria (DOMHaIN; N = 31)). We report Li, Al, Mn, Cu, Zn, Sr, Ba and Pb concentrations (µg/g) and qualitatively examine As, Cd and Hg across all three cohorts. Rates of detection were highest, both overall and for each cohort individually, for Zn, Sr, Ba and Li. Zinc was detected in 100% of samples and was stably present in teeth at a concentration range of 64 - 86 µg/g. Mercury, As and Cd detection rates were the lowest, and had high variability within individual ablated spots. We found the highest concentrations of Pb in the pre- and postnatal dentin of the SLBT cohort, consistent with the prevalent use of Pb as an additive to gasoline prior to 1975. The characteristic decline in Mn after the second trimester was observed in all cohorts. Spatially resolved elemental analysis of deciduous teeth combined with methods for estimating crown formation times can be used to reconstruct an early-life history of elemental exposure inaccessible via other biomarkers. Quantification of data into absolute values using an external standard reference material has not been conducted since 2012, preventing comparison between studies, a common and highly informative component of epidemiology. We demonstrate, with three contrasting populations, that absolute quantification produces data with the lowest variability, compares well with available data and recommends that future tooth biomarker studies report data in this way.

Oxidized Bisindolyl-Based Amphiphilic Probe for Dual Mode Analysis of Heavy Metal Pollutants in Aqueous Medium.

The oxidized bisindolyl-based amphiphilic, chromogenic probe has been synthesized that can form nanoscopic aggregates in the aqueous medium. Along with solvent polarity and pH of the medium, it was observed that the addition of heavy metal pollutants, like Hg2+ can cause significant alteration in the charge transfer state. This resulted in the immediate change in the solution color from yellow to orange. Additionally, we could excite either the monomer species or the aggregates of the probe by choosing the proper excitation wavelength. Upon exciting at 390nm, the compound exhibited a broad fluorescence spectrum with maxima at 450nm, presumably due to twisted state charge transfer. On the contrary, the aggregated species (λex = 465nm) displayed a comparatively weaker fluorescence band centered at 565nm. Interestingly, the fluorescence intensity at the 450nm band experience fluorescence quenching in the presence of Hg2+ ion, while the aggregate emission band remained unaffected. Finally, the present system was utilized for detection of mercury ions in natural water samples.

Synthesis of graphitic carbon nitride-enhanced manganese oxide microspheres for ultra-sensitive electrochemical detection of mercury (II) in environmental water sample

Mercury (Hg2+) is a highly toxic heavy metal in environmental water samples, resulting from improper releases, and causing widespread contamination with significant impacts on human health. Developing an appropriate method for detecting the toxic metal Hg2+ is crucial. Despite manganese oxide (MnO2) being employed for Hg2+ detection, its suboptimal electrocatalytic performance, due to inadequate electrical conductivity, stability, and chemical reactivity, prompted our innovative approach. We addressed this issue by utilizing a nitrogen-rich carbon source, 2D graphitic carbon nitride (g-C3N4), in conjunction with MnO2, crafting the MnO2@g-C3N4 composite to boost Hg2+ capabilities. A thorough analysis of the MnO2@g-C3N4 composite explored its structural, physical, and chemical properties, while different electrochemical techniques were employed to evaluate its electrocatalytic behavior. Consequently, MnO2@g-C3N4 composite-modified screen-printed carbon electrode (MnO2@g-C3N4@SPCE) demonstrated notable characteristics, including a detection limit (2.6 nM), an extended linear range, superior selectivity, and repeatability in Hg2+ detection. Moreover, the MnO2@g-C3N4 sensor, with a high recovery rate for Hg2+ in real sample analysis, particularly river water, showcased its excellent practicality attributed, to the synergistic effect between MnO2 and g-C3N4, providing numerous electroactive sites.

A novel functionalized graphdiyne oxide membrane for efficient removal and rapid detection of mercury in water

In practice, efficient, rapid and simple removal of Hg(II) from water using nano adsorbents remains an extreme challenge at present. In this work, a novel Hg(II) adsorbent based on functionalized graphdiyne oxide (GDYO-3M) membrane was designed for the purpose of effective and prompt removal of Hg(II) from environmental water for the first time. Through filtration, the proposed GDYO-3M membrane (4 cm diameter size) fulfilled an exceeding 97% removal efficiency in > 10 L water containing 0.1 mg/L Hg(II) within 1 h. Due to the presence of -SH groups, the GDYO-3M membrane demonstrates an excellent selectivity for Hg(II) vs. 14 co-existing metal ions. In the meantime, the GDYO-3M membrane represents a favorable reproducibility (above 95% Hg(II) removal) after 9 successive adsorption-desorption cycles. For the mechanism, it is believed that the active sites in the adsorption process mainly include -SH groups, oxygen-containing functional groups, and alkyne bonds. Further, the GDYO-3M membrane can be utilized as an enrichment approach for sensitive analysis of Hg(II) in water based on energy dispersion X-ray fluorescence spectrometry (ED-XRF), whose detection limit (LOD) reaches 0.2 μg/L within 15 min. This work not only provides a green and efficient method for removing Hg(II), but also renders an approach for rapid, sensitive and portable Hg(II) detection in water.

Investigation of the Application and Mechanism of Nitrogen and Phosphorus Co-doped Carbon Dots for Mercury Ion Detection.

In this paper, we obtained nitrogen and phosphorus co-doped carbon dots through a hydrothermal method using o-phenylenediamine and citric acid in a 40% phosphoric acid environment. The carbon dots emitted fluorescence at 476nm under excitation at 408nm and exhibited good selectivity and high sensitivity towards mercury ions. These carbon dots showed excellent dispersibility in water and maintained stable fluorescence even in high concentration salt environments. The interaction between mercury ions and functional groups on the carbon dots surface through electrostatic interaction resulted in static quenching. Simultaneously, by detecting the lifetime and transient absorption spectra of the carbon dots, we observed that the coordination of mercury ions with the carbon dots broadened the band structure of the carbon dots, and the existing photoinduced electron transfer process increased the non-radiative transition channel. The combined effect of dynamic quenching and static quenching significantly reduced the fluorescence intensity of the carbon dots at 476nm. The carbon dots exhibited linear detection of mercury ions in the range of 0.01-1 µM, with a detection limit as low as 0.0245 µM. In terms of practical water environmental detection applications, these carbon dots were able to effectively detect mercury ions in tap water and lake water, demonstrating their broad application prospects in the field of environmental metal analysis.

Label-free fluorescence detection of mercury ions based on thymine-mercury-thymine structure and CRISPR-Cas12a

In this work, we developed a novel label-free fluorescent sensor for the highly sensitive detection of mercury ions (Hg2+) based on the coordination chemistry of thymine-Hg2+-thymine (T-Hg2+-T) structures and the properties of CRISPR-Cas12a systems. Most notably, two T-rich sequences (a blocker and an activator) were designed to form stable double-stranded structures in the presence of Hg2+ via the T-Hg2+-T base pairing. The formation of T-T mismatched double-stranded DNA between the blocker and the activator prevented the cleavage of G-rich sequences by Cas12a, allowing them to fold into G-quadruplex-thioflavin T complexes, resulting in significantly enhanced fluorescence. Under the optimized conditions, the developed sensor showed an excellent response for Hg2+ detection in the linear range of 0.05 to 200 nM with a detection limit of 23 pM. Moreover, this fluorescent sensor exhibited excellent selectivity and was successfully used for the detection of Hg2+ in real samples of Zhujiang river water and tangerine peel, demonstrating its potential in environmental monitoring and food safety applications.

Dual-Responsive Hydrogels for Mercury Ion Detection and Removal from Wastewater.

This study describes the development of a fast and cost-effective method for the detection and removal of Hg2+ ions from aqueous media, consisting of hydrogels incorporating chelating agents and a rhodamine derivative (to afford a qualitative evaluation of the heavy metal entrapment inside the 3D polymeric matrix). These hydrogels, designed for the simultaneous detection and entrapment of mercury, were obtained through the photopolymerization of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPSA) and N-vinyl-2-pyrrolidone (NVP), utilizing N,N'-methylenebisacrylamide (MBA) as crosslinker, in the presence of polyvinyl alcohol (PVA), a rhodamine B derivative, and one of the following chelating agents: phytic acid, 1,3-diamino-2-hydroxypropane-tetraacetic acid, triethylenetetramine-hexaacetic acid, or ethylenediaminetetraacetic acid disodium salt. The rhodamine derivative had a dual purpose in this study: firstly, it was incorporated into the hydrogel to allow the qualitative evaluation of mercury entrapment through its fluorogenic switch-off abilities when sensing Hg2+ ions; secondly, it was used to quantitatively evaluate the level of residual mercury from the decontaminated aqueous solutions, via the UV-Vis technique. The ICP-MS analysis of the hydrogels also confirmed the successful entrapment of mercury inside the hydrogels and a good correlation with the UV-Vis method.

A highly conductive and mesoporous samarium metal–organic nanorods for the trace-level electrochemical detection of toxic mercury ions in lake water

The research outlines an ultrasensitive electrochemical detection of trace-level mercury using an Sm-BTC metal–organic framework. The Sm-BTC metal–organic framework was synthesized via a simple solvothermal method and characterized through various analytical techniques. The FTIR spectrum shows two important peaks at 732 cm−1 and 554 cm−1 which confirms the formation of the metal–organic framework and the surface morphology of the material was characterized through SEM analysis which shows the multilayered nanorod structure. The mesoporous nature of the material was confirmed by BET analysis. The electrochemical studies including Cyclic voltammetry and Square wave voltammetry prove the Sm-BTC modified glassy carbon electrode has shown remarkable sensitivity and selectivity towards the sensing of mercury ions than the unmodified bare glassy carbon electrode. The Sm-BTC modified GCE with the optimized electrochemical parameters for the sensing of mercury ions confirms that the sensor has a very low LOD (Limit of Detection) of 10 nM. It is lower than the guideline concentration of mercury (30 nM) by the World Health Organization and the linear range is 0.01 µM to 50 µM with a correlation coefficient of 0.9926. Further, this sensor has shown an excellent sensitivity of 91.760 µA µM−1 cm−2. The real sample analysis of the current study proves the reported sensor is effective for the determination of Hg2+ ions as it shows a very good recovery percentage.

Extraction and detection of mercury in electronic waste using efficient modified MOF

The harmful effects of heavy metal ions on human health and the ecosystem have made the detection of these ions in environmental samples increasingly important in recent years. There has been significant attention on the development of sensors that are selective and sensitive in detecting heavy metal ions. Due to their wide presence in the environment and high toxicity, the detection of Hg2+ ions is of great interest. MIL-101(Al)-N = 2NAPHT (2NAPHT = 3-hydroxy-2-naphthaldehyde, N = imine nitrogen) is a novel chemosensor that was solvothermally synthesized and characterized. A limit of detection of 5.48 ppb (2.73 ×10−8 M) was found for the chemosensor, which is highly selective and sensitive to Hg2+ ion detection. The fluorescence emission properties of MIL-101(Al)-NH2 were improved and more binding sites for analytes were introduced after functionalization with 2-hydroxy naphthaldehyde. The formation of the novel chemosensor was confirmed by using Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), TEM, SEM, thermogravimetric analysis (TGA), and X-ray diffraction (XRD). Moreover, this chemosensor showcased a regenerative emission feature, retaining its detection ability for six successive cycles. The study revealed that the sorbent had a considerable Hg2+ capacity, amounting to 133.2 mg per gram of MIL-101(Al)-N = 2NAPHT chemosensor. The chemosensor MIL-101(Al)-N = 2NAPHT was also assessed for its capability to identify Hg2+ ions in electronic waste samples (silver oxide button cells). According to the results mentioned above, the chemosensor exhibited a high degree of sensitivity and selectivity towards Hg2+ ions. The MIL-101(Al)-N = 2NAPHT chemosensor is an effective and promising technology for the detection and removal of mercury from electronic waste, in conclusion.

Characterization and Application of Carbon Paste Electrode Modified by Moringa Oleifera Seed Powder to the Electrochemical Detection of Mercury

Heavy metal pollution of surface waters from anthropogenic activities is constantly increasing. Monitoring techniques must therefore be more precise and more sensitive. One of the effective methods available is the development of sensitive electrochemical sensors, dedicated to the analysis of pollutants in aqueous solution. The carbon paste electrode (CPE) in this study was modified with Moringa Oleifera seed powder, a flocculant-adsorbent used to treat water. This chemically modified electrode presented improved electrochemical reactivity in cyclic votammetry towards the redox marker Ferri / Ferrocyanide compared to the bare carbon paste electrode. The 10 % modifier presented the most interest during the analysis. The Modified electrode was used to detect mercury (II) in anodic stripping voltammetry. The detection current of mercury (II) is seven times that of carbon paste electrode (CPE). The calibration curve is linear in the range from 0.002 μmol/L to 0.009 μmol/L (0.4 μg/L to 1.8 μg/L) with a detection limit of 0.4 ηmol/L (i.e.0.08 μg/L). This new technique can be used for routine monitoring of real aqueous matrices.