Detection Of Mercury Research Articles

Highly Efficient Multi‐Tasking Porphyrin‐Based Chemosensor for Mercury Ions

AbstractPorphyrin‐based monomeric and polymeric sensors are emerging as a desirable alternative to efficient sensors due to their unique optical properties and biocompatibility. An efficient new sensor Acpmono and Acppoly were designed and synthesized for selective and efficient mercury detection at ppm‐level. UV‐visible and fluorescence spectroscopic techniques were studied for the sensing performance of both the monomeric and the polymeric sensors. Mechanism of interaction between sensors was confirmed by proton nuclear magnetic resonance (NMR) titration, Ultraviolet‐visible and fluorescence spectroscopic titration, mass spectrometry, time‐correlated single‐photon count (TCSPC) study. Furthermore, a “turn‐off” mode has been established to detect noble heavy metal mercury (Hg2+) by quenching the red fluorescence of sensor molecules. The real‐time application of Acpmono and Acppoly were studied by preparing paper strips and detecting Hg2+ from beauty products in a facile way. Cell viability was evaluated for sensors Acpmono and Acppoly to living HeLa cells using the MTT assay technique to investigate the applicability of the sensors in a biological medium. Based on the MTT assay data of both monomeric and polymeric sensors, the cell imaging of endogenous Hg2+ ions was explored in living HeLa cells.

Recent Trends and Future Perspectives of Emergent Analytical Techniques for Mercury Sensing in Aquatic Environments.

Environmental emissions of mercury from industrial waste and natural sources, even in trace amounts, are toxic to organisms and ecosystems. However, industrial-scale mercury detection is limited by the high cost, low sensitivity/specificity, and poor selectivity of the available analytical tools. This review summarizes the key sensors for mercury detection in aqueous environments: colorimetric-, electrochemical-, fluorescence-, and surface-enhanced Raman spectroscopy-based sensors reported between 2014-2021. It then compares the performances of these sensors in the determination of inorganic mercury (Hg2+ ) and methyl mercury (CH3 Hg+ ) species in aqueous samples. Mercury sensors for aquatic applications still face serious challenges in terms of difficult deployment in remote areas and low robustness, reliability, and selectivity in harsh environments. We provide future perspectives on the selective detection of organomercury species, which are especially toxic and reactive in aquatic environments. This review is intended as a valuable resource for scientists in the field of mercury sensing.

Fast and efficient “on-off-on” fluorescent sensor from N-doped carbon dots for detection of mercury and iodine ions in environmental water

A kind of nitrogen doped carbon dots (N-CDs) was facilely fabricated from polyethyleneimine and anhydrous citric acid, and which was adopted to develop a neoteric “on-off” and “off-on” fluorescent sensor for rapidly and efficiently sensing Hg2+ and I−. The fluorescence of N-CDs was notably quenched (off) in the existence of Hg2+ derived from strong interaction and the electron transfer between N-CDs and Hg2+, while the quenched fluorescence of the N-CDs and Hg2+ system was strikingly regained by addition of I− (on) resulted from the separation of N-CDs and Hg2+ due to the higher binding preference between Hg2+ and I−. Under optimal conditions, the linear detection ranges were 0.01–20 μM for Hg2+ and 0.025–7 μM for I−, respectively. Meanwhile, the detection limits could be down to 3.3 nM for Hg2+ and 8.5 nM for I−, respectively. Satisfied recoveries had also been gained for measuring Hg2+ and I− in practical water samples. The constructed “on-off-on” fluorescent sensor provided a simple, rapid, robust and reliable platform for detecting Hg2+ and I− in environmental applications.

Determination of Mercury in Artificial Saliva Extract of Chewing Tobacco by Dispersive Liquid–Liquid Micro-Extraction Using Electrothermal Atomic Absorption Spectrometry (ETAAS)

An enrichment method was developed for the determination of inorganic mercury (Hg) in artificial saliva extracts (ASE) of frequently consuming chewing tobacco products (CTP). The artificial saliva extracts of the mainpuri and gutkha chewing tobacco were subjected to dispersive liquid-liquid micro-extraction (DLLµE) based on the ultrasound based back extraction of hydrophobic complex of inorganic mercury (iHg) separately by L-cysteine and hydrochloric acid. The total Hg, extractable Hg (EHg), and enriched inorganic mercury in artificial saliva extracts of chewing tobacco were determined by electrothermal atomic absorption spectrometry (ETAAS) and inductively coupled plasma – optical emission spectrometry (ICP-OES). The results obtained by these techniques were not significantly different (p > 0.05). Factors affecting the extraction efficiency of inorganic mercury such as concentration of the ligand, pH, disperser/extracting solvent, sonication time, and back extracting reagents were optimized by multivariate techniques. The precision and accuracy of total mercury (tHg) was confirmed by analyzing a tobacco certified reference material, while the validity of the proposed method (DLLµE) was ensured by spiking inorganic mercury in artificial saliva extracts of the chewing tobacco products. Using the optimized conditions for developed method, the limit of detection and enrichment factor for inorganic mercury were 0.17 μg/L and 96.2, respectively. The extractable Hg in artificial saliva extracts of chewing tobacco was from 35 to 48% of the total content. However, the concentration of inorganic mercury was between 68 and 80% of the total extractable concentration in artificial saliva extracts of the chewing tobacco.

A FRET-based ratiometric fluorescent probe with large pseudo-stokes for the detection of mercury ion based on xanthene and naphthalimide fluorophores

In this work, a novel colorimetric and ratiometric fluorescent probe (R1) for detecting Hg2+ based on xanthene and naphthimide groups via the fluorescence resonance energy transfer (FRET) mechanism was designed and synthesized. In the CH3CN/H2O (1/1, v/v) system, the probe R1 showed ratiometric fluorescent responsiveness to Hg2+ with the characteristics of rapid response time (less than 30 s), high selectivity and excellent anti-interference ability, meanwhile, the fluorescence color changed from cyan to orange and the solution color changed from colorless to pink by naked-eye. Based on fluorescence and UV/vis measurements, the limit of detection (LOD) was calculated to be 1.14 μM and 0.17 μM, respectively. Furthermore, the possible mechanism for the detection of Hg2+ of probe R1 was verified by using ESI-MS, 1H NMR and HPLC spectra.

Electrochemical sensor based on MoS2 nanosheets and DNA hybridization for trace mercury detection

• Chitosan/GO/MoS 2 /AuNPs and T-Hg 2+ -T base pair were used to form an electrochemical sensor with low detection limit, good repeatability, and specificity. • MoS 2 nanosheets were used as a substrate for the immobilization of DNA and amplified the electrochemical signal produced by the sensor. • A novel electrochemical method for trace Hg 2+ detection in water was developed. Mercury ions (Hg 2+ ) are highly toxic and can cause serious harm to the environment and human health. In this study, we prepared a novel electrochemical sensor based on an electrode coated with chitosan/graphene oxide/molybdenum disulfide/Au nanoparticles (chitosan/GO/MoS 2 /AuNPs) and thymine-Hg 2+ -thymine base pair to detect trace Hg 2+ in water. This method effectively utilized the affinity of MoS 2 to immobilize deoxyribonucleic acid (DNA) on the electrode surface and enabled the amplification of the electrochemical signals detected by the sensor. The specific binding of the thymine-Hg 2+ -thymine base pair and the electrochemical activity of MoS 2 successfully reduced the detection limit of Hg 2+ and rendered it interference resistant. In the presence of Hg 2+ , a double-stranded structure was formed on the electrode after the interaction between Hg 2+ and DNA, which caused the change of the oxidation current signal of the electrode surface. The sensor showed good linearity ranging from 0.01 μg/L to 4 μg/L with a correlation coefficient of 0.991, and the limit of detection was found to be 5.8 ng/L. This portable chitosan/GO/MoS 2 /AuNPs modified electrode showed satisfactory recovery in tap water samples, thus demonstrating its potential for application in trace Hg 2+ detection.

Amperometric Detection of Mercury Ions Using Piperazine‐Functionalized Reduced Graphene Oxide as an Efficient Sensing Platform

AbstractIn this work, employing the Hibiscus rosa sinensis (HRS) flower extract as a green reducer for graphene oxide (GO) reduction and functionalization of rGO using piperazine is proposed. A chemically modified screen‐printed carbon electrode (SPCE) was prepared using piperazine functionalized reduced graphene oxide (P‐rGO). Electroanalytical techniques such as amperometry and differential pulse voltammetry (DPV) were used to investigate the sensing capability of P‐rGO modified SPCE towards the detection of Hg2+ ions. The oxidation peak observed in the cyclic voltammetry was due to the interaction between piperazine (amine) and mercury ions. Piperazine plays a major role in improving the sensitivity of the developed sensor towards mercury cation detection, while the P‐rGO is used as a platform for the incorporation of Hg2+.The developed sensor exhibits a high sensitivity of 0.00327 μA/pM over a wide linear range of 0.2 pM to 2 pM, with a detection limit of 0.0557 pM.

Design and synthesis of colorimetric sensor based on dithizone@TiO2/poly (tert-butyl acrylate-acrylic acid) nanocomposite for fast visual detection of mercury, lead and cadmium ions in aqueous media

This paper presents the selective detection of Hg(II), Pb(II) and Cd(II) in aqueous solution via applications of dithizone(DTZ)@TiO2/poly (tert-Butyl acrylate(TBA)-acrylic acid(AA)) nanocomposites as fast colorimetric sensor. The ion sensing polymeric nanocomposite was prepared by incorporating DTZ as chromoionophore in the polymeric nanocomposite membrane containing TBA as leaving groups. This nanostructured composite with DTZ loaded polymeric shell was utilized as a fast, sensitive and selective sensor for detection of Hg(II), Pb(II) and Cd(II) in aqueous solution at optimum condition. The adsorption of Hg(II), Pb(II) and Cd(II) increased with increasing pH until it reached at around pH = 8.0, pH = 6.0 and pH = 7.0, respectively. The proposed sensor displays a wide linear range of [(10 ppb–10 ppm)], [(20 ppb)] and [(10 ppb)] with a low detection limit of 10 ppb, 20 ppb and 10 ppb for Hg(II), Pb(II) and Cd(II) solutions, respectively, and also this sensor has a relatively quick response time less than 1 min. The DTZ-anchored polymeric nanocomposite is appropriate to use a repeated measures (for more than four cycles) without any noticeable capacity loss. The outstanding properties of synthesized chemosensor are the fast, selective, easy-to-use, portable and inexpensive screening-test for recognizing Hg(II), Pb(II) and Cd(II) contamination in aqueous solution to avoid time-consuming and costly determination using instrumental techniques. The prepared colorimetric sensor were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX) analysis, transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and X-ray powder diffraction (XRD).

A comparative study of metal–organic frameworks for mercury detection in competitive aqueous environment

A comparative study of metal–organic frameworks for mercury detection in competitive aqueous environment

Hg(II) Ion-Selective Electrodes with PVC Membranes Based on Bis-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one

Abstract A new solid-state contact potentiometric membrane electrode was developed based on bis-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one (ionophore), which acts selectively towards the mercury(II) ion. The ionophore was synthesized by the treatment of an amino derivative with oxybis dibenzaldehyde. The potentiometric behavior of an electrode was investigated in the concentration range from 1.0 × 10−2 to 1.0 × 10−6 mol L−1 for mercury(II) ion. The electrode displayed a good linearity (R2 = 0.9997) with the detection limit of 1.2 × 10−7 mol L−1 and showed a very high selectivity against Hg(II) ion without being affected by the presence of interfering ions. The electrode exhibited a potential change of 62.0 ± 2.0 mV for each ten-fold increase in concentration of mercury(II) ion. Potentiometric response of the electrode was investigated in the pH range from 3.0 to 10.0. In addition to this electrode being used to determine mercury(II) in different water samples, it can also be used with EDTA as an indicator electrode in the potentiometric titration of mercury(II) ion. Since the developed electrode displayed good potentiometric performance, it has potential to be used in environmental and biological samples for detection of mercury(II) ions.

Rhodamine functionalized cellulose for mercury detection and removal: A strategy for providing in situ fluorimetric and colorimetric responses

A new cellulose-based material as adsorbent was prepared for Hg (II) detection and removal from aqueous solution. Rhodamine moiety was conjugated with cellulose as an efficient sensor, enabling the material to exhibit excellent optical signals on the contact with Hg (II). Fourier transform infrared spectra, elemental analysis, thermogravimetry, differential thermal analysis, scanning electron microscope analysis, Brunauer-Emmett-Teller surface area, pore volume and pore size were employed to verify the modification of cellulose. A 7-fold enhancement of fluorescence intensity afforded the adsorbent “off–on” fluorimetric response exclusively towards Hg (II) without the interference of more than ten other kinds of metal ions. The detection limit reached as low as 9.18 × 10-7 M. Besides, the adsorbent also showed an obvious color change during the adsorption to realize “naked-eye” recognition with Hg (II) in the range of 1–400 ppm. Thus, a colorimetric card was prepared to evaluate the concentration of Hg (II) in a convenient and rapid manner. In addition, the adsorption properties of the material including the effect of initial concentration, pH, and contact time were systematically investigated by batch adsorptions. The adsorption process was found to fit well with Langmuir adsorption model and pseudo-second-order kinetics. The mercury triggered spirolactam ring-opening reaction was responsible for the sensitive and selective fluormetric sensing and confirmed by the Job’s plot (1:1 binding stoichiometry) and X-ray photoelectron spectroscopy. Furthermore, density functional theory studies also indicated the energetically favorable Hg (II) induced ring-opening process. The highly sensitive and selective performance in tap water further demonstrated the tremendous potential of as-prepared adsorbent for practical application.

Label-free ultra-low level electrochemical detection of mercury(II) ions in aqueous medium via direct covalent functionalization of single-stranded DNA with MoS2 nanoflakes

Label-free ultra-low level electrochemical detection of mercury(II) ions in aqueous medium via direct covalent functionalization of single-stranded DNA with MoS2 nanoflakes

Achieving Ultrasensitive Point-of-Care Assay for Mercury Ions with a Triple-Mode Strategy Based on the Mercury-Triggered Dual-Enzyme Mimetic Activities of Au/WO3 Hierarchical Hollow Nanoflowers.

The exploration of new strategies for portable detection of mercury ions with high sensitivity and selectivity is of great value for biochemical and environmental analyses. Herein, a straightforward, convenient, label-free, and portable sensing platform based on a Au nanoparticle (NP)-decorated WO3 hollow nanoflower was constructed for the sensitive and selective detection of Hg(II) with a pressure, temperature, and colorimetric triple-signal readout. The resulting Au/WO3 hollow nanoflowers (Au/WO3 HNFs) could efficaciously impede the aggregation of Au NPs, thus significantly improving their catalytic activity and stability. The sensing mechanism of this new strategy using pressure as a signal readout was based on the mercury-triggered catalase mimetic activity of Au/WO3 HNFs. In the presence of the model analyte Hg(II), H2O2 in the detection system was decomposed to O2 fleetly, resulting in a detectable pressure signal. Accordingly, the quantification of Hg(II) was facilely realized based on the pressure changes, and the detection limit could reach as low as 0.224 nM. In addition, colorimetric and photothermal detection of Hg(II) using the Au/WO3 HNFs based on their mercury-stimulated peroxidase mimetic activity was also investigated, and the detection limits were calculated to be 78 nM and 0.22 μM for colorimetric and photothermal methods, respectively. Hence, this nanosensor can even achieve multimode determination of Hg(II) with the concept of point-of-care testing (POCT). Furthermore, the proposed multimode sensing platform also displayed satisfactory sensing performance for the Hg(II) assay in actual water samples. This promising strategy may provide novel insights on the fabrication of a multimode POCT platform for sensitive, selective, and accurate detection of heavy metal ions.

Highly selective and sensitive detection of mercury (II) and dopamine based on the efficient electrochemiluminescence of Ru(bpy)32+ with acridine orange as a coreactant

Developing highly specific, rapid, and cost-effective electrochemiluminescence (ECL) methods capable of detecting multiple analytes remains a compelling research goal but it is still a substantial challenge due to narrow choice of ECL systems. In this study, efficient ECL detections were achieved by using anodic Ru(bpy)32+-acridine orange (AO) ECL system. In present system, dimethylamino substituent on acridine ring acts as active sites for strong ECL generation, while heterocyclic nitrogen atom (–N–) contributes to specific complex formation with metal ion. Accordingly, this anodic ECL method was exploited for highly sensitive detection of both mercury (II) (Hg2+) and dopamine (DA), with detection limits as low as 0.36 nM (linear range 0.01–50 μM) and 1.0 nM (linear range 0.01–10 μM), respectively. The mechanism of Hg2+ detection was supported by density functional theory (DFT) calculations. Notably, the ECL method exhibit superior selectivity over numerous competing interfering agents. Moreover, the method achieved the detection of both targets in practical media with excellent recoveries (96.0–103.8%). Importantly, the method demonstrates potential advantages in terms of selectivity, sensitivity, rapidity, simplicity, and low cost. This work realizes a successful attempt to further expand the analytical applications of ECL systems and may initiate new thoughts in utilizing acridines in diverse ECL-based sensing and imaging applications.

The detection of Mercury(II) ions using fluorescent gold nanoclusters on a portable paper-based device

To minimize the need for complex testing procedures, sophisticated instrumentation, and electricity for on-site testing, we demonstrate a simple and portable gold nanocluster (AuNC)-modified paper analytical device integrated with syringe-driven fluid flow to enable highly sensitive mercury ion (Hg2+) detection for environmental monitoring. The device is composed of a paper substrate modified with fluorescent AuNCs (AuNC-paper), which is held within a reusable cartridge connected to a syringe, thus allowing users to flow a large volume of the sample solution through the paper test for greater accumulation of the analyte signal. The metallophilic d10-d10 interaction of Hg2+ with Au+ on the surface of the AuNC-paper induces fluorescence quenching, which can be monitored using a smartphone. Importantly, the red-emitting AuNCs avoid interference with the background fluorescence of the paper substrate. Additionally, the AuNCs are strongly-attached to the paper substrate via carbodiimide coupling, which helps prevent the AuNCs from leaching and enables a large amount of solution to interact with the test (up to 2.5 mL) to increase the amount of the target ions that react with the AuNC-paper. As a result, without the need for preconcentrating the test solution, this paper device can provide the highly sensitive detection of Hg2+ ions, including a 26-fold higher sensitivity than the AuNC-modified test paper without a fluidic cartridge, at a low level of down to nM. The paper platform can complete the detection of Hg2+ ions within 30 min, with a detection limit as low as 1.2 nM, which is less than the United States Environmental Protection Agency’s regulatory limit for drinking water. This highly sensitive, selective, portable, and easy-to-operate platform may be valuable for on-site mercury pollution monitoring in resource-constrained settings.

Fluorescence/colorimetry dual-mode sensing strategy for mercury ion detection based on the quenching effect and nanozyme activity of porous cerium oxide nanorod

Mercury ion (Hg2+) has become a widespread environmental pollutant in recent decades, thus it is particularly important to accurately identify dangerous concentrations of Hg2+. Herein, we developed a novel fluorescence/colorimetry dual-mode sensing strategy for the detection of Hg2+ by integrating the fluorescence quenching effect and peroxidase-like activity of porous cerium oxide nanorod (P-CeO2 NR). The adsorption of carboxyfluorescein-labeled Hg2+ aptamer (FAM-apt) on the P-CeO2 NR surface could form the P-CeO2 NR/FAM-apt composite. The fluorescence signal of FAM-apt was quenched. Meanwhile, the peroxidase-like activity of P-CeO2 NR was enhanced, accompanied with a color change of the 3,3,5,5-tetramethylbenzidine (TMB)-hydrogen peroxide (H2O2) solution from colorless to blue. In the presence of Hg2+, the formation of thymine-Hg2+-thymine (T-Hg2+-T) structure induced the separation of FAM-apt from the P-CeO2 NR surface, resulting in the recovery of FAM-apt fluorescence. Moreover, the peroxidase-like activity of P-CeO2 NR was decreased and the color of TMB-H2O2 solution turned to light blue. As a result, the developed dual-mode sensing strategy displayed a linear range of 0.08–12.5 nM with an as-detection limit of 0.079 nM for the fluorescence assay, and a range of 0.5–100 nM with a detection limit of 0.31 nM for the colorimetric method. By integrating the high sensitivity of fluorescence and the visual analysis of colorimetry, the proposed dual-mode sensing strategy exhibited high sensitivity, accuracy and reliability. Hence, this novel dual-mode sensing strategy provides a new sensing platform for Hg2+ detection in water samples.

Thermodynamics and kinetics to develop an analytical method for sensing of aqueous Hg(II) using caffeic acid decorated AgNPs

Mercury (Hg) and its compounds are exceptionally noxious and extensively distributed in the atmosphere. We have used caffeic acid decorated silver nanoparticles (CA–AgNPs) for the colorimetric detection of the Hg(II) ions in the aqueous systems. In this method, a paper strip was simply used as a dipstick type device for the fast and selective detection of the aqueous Hg(II) ions. The paper strip displays a color change within 50 seconds with superior selectivity after being dipped into the solution containing a concentration of Hg(II) ions in the range of 20–0.0001 ppm. The developed method allows us to detect Hg(II) through naked eyes with a LOD of 0.0001 ppm. The interaction between prepared CA–AgNPs and Hg(II) was also studied using reactive kinetics, thermodynamic parameters and density functional theory (DFT). The proposed method can be a cost-effective tool for field-level applications for on-site real-time detection of mercury.

Detection and Removal of Mercury Ions in Water by a Covalent Organic Framework Rich in Sulfur and Nitrogen

Hg/Hg(II) is deemed to be the most toxic heavy metal to humans. Therefore, designing suitable adsorbents to simultaneously achieve high capacity, rapid mercury adsorption, and fluorescence detection is still an important challenge in overcoming Hg2+ pollution. Here, we report a flexible alkylamine covalent organic framework (TpTSC), which has been used as an efficient adsorbent and achieves the dual-functional application of TpTSC for Hg2+, with a fluorescence detection limit of 2 ppm and simultaneously a removal capacity of 1035 mg g–1. It can remove 10 ppm mercury solution to below 2 ppb (drinking water standard) within 10 min, and the removal rate is as high as 99.98%. To a certain extent, it exceeds the recently reported thioether or thiol functionalized adsorbents. The kinetic study shows that TpTSC displays a very high Kd value, with Kd = 1.2 × 109 mL g–1, which has a strong affinity for mercury. In addition, TpTSC displays a good recycling capacity, with a removal rate of over 90% after five cycles. In conclusion, sulfur modification is a useful strategy for developing dual-functional COFs to simultaneously remove and detect toxic heavy metal ions.

Mercury(II) stripping electroanalysis with hot microelectrodes

Environmental pollution is one of the major concerns nowadays. Heavy metals play a determining role in deteriorating the environment around us, and mercury is among the top metals responsible for this due to its high toxicity. Thus, it is necessary to identify and minimize the contamination, and effective electroanalytical techniques are necessary to determine the concentration of the toxic metal ion at ever lower levels. The electrochemical detection of mercury(II) at a bare gold microelectrode is investigated and reported here. Linear sweep voltammetry and square wave voltammetry were used to determine low mercury concentration (5 nM) via its stripping. The supporting electrolyte was 0.1 M nitric acid. The Hg-deposition was done at -0.5 V and aided by alternating current (ac) heating, while Hg-stripping was performed at room temperature. The LOD for the developed method was 0.94 nM for 120 s deposition time and we believe even lower detection limits could be achieved by increasing the deposition time.

Adjustable Synthesis of Ni-Based Metal–Organic Framework Membranes and Their Field-Effect Transistor Sensors for Mercury Detection

Adjustable Synthesis of Ni-Based Metal–Organic Framework Membranes and Their Field-Effect Transistor Sensors for Mercury Detection