Concentration Of Mercury Ions Research Articles

Determination of Mercury(II) in Aquatic Plants Using Quinoline-Thiourea Conjugates as a Fluorescent Probe

In this study, a quinoline-thiourea conjugate (1-phenyl-3-(quinoline-8-yl) thiourea, PQT) was synthesized and used as a fluorescence sensor to detect mercury ion. The observation is coincident with the well-documented phenomenon that a thiocarbonyl-containing group on a fluorochrome quenches the fluorescence due to the heavy atom effect of the S atom. The large fluorescence enhancement of PQT in the buffered MeCN-water mixture (1/1 v/v; HEPES 100 mM; pH 8.0) was caused by the Hg(2+) induced transformation of the thiourea function into a urea group. As such, protic solvents can be ascribed to hydrogen bond formation on the carbonyl oxygen to reduce the internal conversion rate. The fluorescence intensity of PQT was enhanced quantitatively with an increase in the concentration of mercury ion. The limit of detection of Hg(2+) was 7.5 nM. The coexistence of other metal ions with mercury had no obvious influence on the detection of mercury. A quinolone-thiourea conjugate was used as a fluorescent probe to detect Hg(2+) in aquatic plants and the experimental results were satisfactory.

DNA functionalized gold nanorods/nanoplates assembly as sensitive LSPR-based sensor for label-free detection of mercury ions

Core–satellite assembly, i.e., gold nanoplates (AuNPs) surrounded by gold nanorods (AuNRs), has been obtained by Thymine–Hg2+–Thymine (T–Hg2+–T) coordination. A novel label-free localized surface plasmon resonance (LSPR) detection of mercury ions can be performed via the core–satellite assembly. The proposed detection protocol exhibits good linear correlation between wavelength shifts of the plasmon band and concentrations of mercury ions over the range from 10nM to 0.2μM. Moreover, the detection limit (3σ) for the probes is 2.2nM, which is better than colorimetric detection via random aggregation of gold nanoparticles.

Palm shell activated carbon impregnated with task-specific ionic-liquids as a novel adsorbent for the removal of mercury from contaminated water

In this study, palm shell activated carbon modified with task-specific ionic liquids was used as a novel composition for the removal of mercury from aqueous solutions in water samples through a batch-adsorption technique. The effect of pH, adsorbent dosage, equilibrium time, temperature and initial concentration of mercury ions on the removal efficiency were examined. The maximum adsorption of mercury at room temperature was 83.33mg/g at pH 8 with a contact time of 3h and an initial concentration of 10–200mg/L. The experimental data were fitted well with the linear form of Langmuir model. Adsorption kinetics followed a pseudo-second-order model. The calculated activation energy for adsorption was 68.21kJ/mol, indicates that the adsorption process involves some chemical forces and occurs by a chemisorption process. Thermodynamic parameters, including ΔH°, ΔS° and ΔG° for the adsorption process of mercury from aqueous solutions onto palm-shell activated carbon impregnated with trioctylmethylammonium thiosalicylate (TOMATS) indicated that adsorption was endothermic and spontaneous process.

Characterization of mercury concentrations in snow and potential sources, Shanghai, China

This work focused on quantifying the total mercury (HgT) and major ion concentrations in snow samples to understand the importance of this pathway and sources of Hg deposited in Shanghai, China. Rare snow event samples were collected at 26 sites within the city of Shanghai on February 18, 2006, January 27, 2008 and January 20, 2011. The sites were distributed among four main functional area types (i.e., industrial impacted, residential impacted, traffic impacted sites and sites in the city center). Concentrations of HgT and major soluble ions, and pH values were determined for each site. Mean HgT concentrations for all sites were 78±52ngL−1, 277±184ngL−1, 189±123ngL−1 in 2006, 2008 and 2011, respectively. Values were higher in Shanghai than observed in other cities including Beijing which has a smaller population and is less industrial. Principle component analysis (PCA) indicated that secondary aerosols (SO42−, NO3− and NH4+), and biomass combustion (K+, CH3COO−, and HCOO−) were best related to mercury concentrations in the snow in 2008 and 2011. Although HYSPLIT back trajectory modeling indicated air mass transport from areas with significant coal combustion, results indicate that anthropogenic pollution from within Shanghai was the predominant source of Hg in snow.

Protective effect of combined therapy with dithiothreitol, zinc and selenium protects acute mercury induced oxidative injury in rats

The present study was undertaken to establish mode of action, comparative therapeutic efficacy and safety evaluation of dithiothreitol (DTT) supplemented with Zn and Se against dimethylmercury in rats. Adult male albino rats of Sprague-Dawley strain (150±10g, n=6 per group) were exposed a bolus dose of dimethylmercury (10mg/kg, p.o.) for once only followed by DTT (15.4mg/kg, i.p.) along with the combination of antioxidants Zn and Se (2mmol/kg and 0.5mg/kg, p.o.) after 72h of toxicant administration for three days. The results showed a significant (P≤0.05) increase in the activities of AST, ALT, alkaline phosphatase, lactate dehydrogenase, in serum after toxicant administration. This was accompanied by histopathological observations. A significant rise was observed in lipid peroxidation level and mercury ion concentration however reduced glutathione content decreased in liver, kidney and brain. A significant (P≤0.05) decrease in the activity of acetyl cholinesterase was also seen in different regions of brain. Combined treatment of DTT along with Zn and Se significantly (P≤0.05) recouped the alterations in the enzymatic activities of serum and reversed the tissue biochemical and histopathological changes of liver, kidney and brain. Our results demonstrate that combined treatment of thiol chelator (DTT) along with antioxidants (Zn and Se) plays an important role against dimethylmercury induced tissue damage and hepatic, nephro and neurotoxicity.

Removal of Mercury from Aqueous Solution Using Sheep Bone Charcoal

The carbon derived from sheep bone with zinc chloride activation was applied for the adsorption of mercury (II). The effect of solution temperature, adsorption time, pH value and initial concentration of mercury(II) ions on the adsorption ability was investigated in a bfigatch process mode. The morphology and structure were characterized by scanning electron microscopy and X-ray diffraction. The BET surface area and pore volume of the prepared sheep bone charcoal were 83.98 m2/g and 0.246 cm3/g, respectively. The equilibrium data were fitted to linear and Freundlich isotherm.

Ligand effect on the luminescence of gold nanodots and its application for detection of total mercury ions in biological samples

In this study, we found that the photoluminescence (PL) of 11-mercaptoundecanoic acid (11-MUA)-protected gold nanodots (Au NDs; ca. 2.0 nm) was highly dependent on the capping ligands and the ligand density. Deposition of 11-MUA onto the surfaces of as-prepared gold nanoparticles (Au NPs; ca. 3.0 nm) yielded luminescent 11-MUA-capped Au NDs (11-MUA-Au NDs). The PL intensity (excitation/emission: 375/525 nm) of the Au NDs decreased dramatically after purification through centrifugation (purified Au NDs are denoted herein as p11-MUA-Au NDs) as a result of a decrease in the 11-MUA ligand density on the Au NDs. Moreover, the PL intensity of the purified Au NDs was recovered after introducing new mercaptoaliphatic acid ligands (the ligand-recapped Au NDs are denoted as Au NDs@ligand; e.g., the 11-MUA recapped Au NDs are denoted as Au NDs@11-MUA). The PL intensity of the Au NDs@ligand species increased upon increasing the ligand density and chain length. Furthermore, using the Au NDs@11-MUA as a probe allowed us to detect the total concentration of mercury ions {inorganic mercury [Hg(II)] plus organic mercury (methylmercury [MeHg(I)], ethylmercury [EtHg(I)] and phenylmercury [PhHg(I)])} in aqueous solution. The selectivity of this nanosensor system for the total mercury over other metal ions is remarkably high (1000-fold), with a limit of detection (LOD, S/N = 3) for mercury ions of 2.0 nM. We have demonstrated the practicality of this approach for the determination of mercury ions in complicated biological urine and plasma samples, as well as in a fish sample (DORM II). This simple, sensitive and selective approach appears to have practical potential for use in the clinical screening of mercury ions in biofluids.

A simple colorimetric assay for the detection of metal ions based on the peroxidase-like activity of magnetic nanoparticles

Abstract We developed a simple colorimetric assay for the detection of metal ions based on the peroxidase-like activity of magnetic nanoparticles (MNPs) and their interactioin with target specific single-stranded DNA (ssDNA). It was already known that MNPs easily oxidize substrates in the presence of hydrogen peroxide same as a peroxidase. In this study, the target specific ssDNA was adsorbed on the positively charged surface of MNP, then the catalytic activity of MNPs was reduced by the screening effect of adsorbed ssDNA on the surface of MNPs to substrates. The peroxidase like activity of MNPs was recovered by the addition of targets because the target specific ssDNA were displaced from MNPs by the interaction between targets and their specific ssDNA. The degree of color change of mixture was proportional to the concentration of mercury ion in a range of 5–75 μM. In control experiment, other metal ions did not induce the color change.

Determination of Mercury (II) Ions by Modified Carbon Paste Electrode Based on Functionalized Nanoporous MCM-48 and Multi-Walled Carbon Nanotubes (MWCNTs)

A carbon paste electrode for determination of mercury (II) ions in real samples was prepared. The main objective of the present study was to evaluate the concentration of mercury ions in different soil, water, plant, and animal muscle samples by utilizing modified carbon paste electrode. Functionalized nanoporous MCM-48 and multi-walled carbon nanotubes material were used in order to increase the efficiency and selectivity of the electrode for mercury ions determination. The electrode composition material was optimized as graphite powder 57%, Paraffin 22%, modified MCM-48 16% and MWCNTs 5% (W/W). The linear range of the electrode was calculated 5.0×10-8 to 1.0×10-3 mol L-1, and a detection limit was obtained 1.5×10-8 mol L-1. The potential slope was achieved 29.7±1.0 mV, and lifetime for the electrode was investigated about 5 months. The proposed method was applied to a number of natural samples and the amount of mercury was determined.

An ion-imprinted polymer for the selective extraction of mercury(II) ions in aqueous media

A double-imprinted polymer exhibiting high sensitivity for mercury(II) in aqueous solution is presented. Polymer particles imprinted with mercury(II) were synthesised by copolymerising the functional and cross-linking monomers, N’–[3– (Trimethoxysilyl)–propyl]diethylenetriamine (TPET) and tetraethylorthosilicate (TEOS). A double-imprinting procedure employing hexadecyltrimethylammonium bromide (CTAB), as a second template to improve the efficiency of the polymer, was adopted. The imprinted polymer was characterised by FTIR, scanning electron microscopy (SEM) and the average size determined by screen analysis using standard test sieves. Relative selective coefficients (k`) of the imprinted polymer evaluated from selective binding studies between Hg 2+ and Cu 2+ or Hg 2+ and Cd 2+ were 10 588 and 3 147, respectively. These values indicated highly-favoured Hg2+ extractions over the 2 competing ions. The results of spiked and real water samples showed high extraction efficiencies of Hg 2+ ions, (over 84%) as evaluated from the detected unextracted Hg 2+ ions by ICP-OES. The method exhibited a dynamic response concentration range for Hg 2+ between 0.01 and 20 µg/ml, with a detection limit (LOD, 3σ) of 0.000036 µg/ml (36 ng/l) that meets the monitoring requirements for the USA EPA of 2 000 ng/l for Hg 2+ in drinking water. Generally, the data (n=10) had percentage relative standard deviations (%RSD) of less than 4%. Satisfactory results were also obtained when the prepared sorbent was applied for the pre-concentration of Hg2+ from an aqueous certified reference material. These findings indicate that the double-imprinted polymer has potential to be used as an efficient extraction material for the selective pre–concentration of mercury(II) ions in aqueous environments.

Hg(II) Ion Detection Using Thermally Reduced Graphene Oxide Decorated with Functionalized Gold Nanoparticles

Fast and accurate detection of aqueous contaminants is of significant importance as these contaminants raise serious risks for human health and the environment. Mercury and its compounds are highly toxic and can cause various illnesses; however, current mercury detectors suffer from several disadvantages, such as slow response, high cost, and lack of portability. Here, we report field-effect transistor (FET) sensors based on thermally reduced graphene oxide (rGO) with thioglycolic acid (TGA) functionalized gold nanoparticles (Au NPs) (or rGO/TGA-AuNP hybrid structures) for detecting mercury(II) ions in aqueous solutions. The lowest mercury(II) ion concentration detected by the sensor is 2.5 × 10(-8) M. The drain current shows rapid response within less than 10 s after the solution containing Hg(2+) ions was added to the active area of the rGO/TGA-AuNP hybrid sensors. Our work suggests that rGO/TGA-AuNP hybrid structures are promising for low-cost, portable, real-time, heavy metal ion detectors.

Sensitive label-free oligonucleotide-based microfluidic detection of mercury (II) ion by using exonuclease I

Mercury is a highly toxic metal that can cause significant harm to humans and aquatic ecosystems. This paper describes a novel approach for mercury (Hg2+) ion detection by using label-free oligonucleotide probes and Escherichia coli exonuclease I (Exo I) in a microfluidic electrophoretic separated platform. Two single-stranded DNAs (ssDNA) TT-21 and TT-44 with 7 Thymine–Thymine mispairs are employed to capture mercury ions. Due to the coordination structure of T–Hg2+–T, these ssDNAs are folded into hairpin-like double-stranded DNAs (dsDNA) which are more difficult to be digested by Exo I, as confirmed by polyacrylamide gel electrophoresis (PAGE) analysis. A series of microfluidic capillary electrophoretic separation studies are carried out to investigate the effect of Exo I and mercury ion concentrations on the detected fluorescence intensity. This method has demonstrated a high sensitivity of mercury ion detection with the limit of detection around 15nM or 3ppb. An excellent selectivity of the probe for mercury ions over five interference ions Fe3+, Cd2+, Pb2+, Cu2+ and Ca2+ is also revealed. This method could potentially be used for mercury ion detection with high sensitivity and reliability.

화학발광법에 의한 수용액 중의 선택적 수은(II) 이온 정량

루미놀 화학발광 시스템(luminol-<TEX>$H_2O_2$</TEX>)을 이용하여 수용액 중의 수은(II) 이온을 선택적으로 정량분석 하였다. 루미놀과 과산화수소의 반응에서 촉매작용을 하는 구리(II), 철(III), 크롬(III) 이온 등 다양한 금속이온의 농도를 정량분석한 연구결과가 보고되어 있다. 본 연구에서는 수은(II) 이온이 루미놀과 과산화수소의 반응에서 다른 금속이온과 같이 촉매작용을 하는 것을 관찰하였으며, 수용액 중 수은(II) 이온의 정량분석 조건을 최적화하기 위하여 반응시간, pH등에 따른 영향을 조사하였다. 또한 수은이온이 갖는 1가와 2가 산화수 중에서 수은(I) 이온은 루미놀과 과산화수소의 반응에 있어서 촉매작용을 하지 않았을 뿐만 아니라 반응에 어떠한 영향도 미치지 않았다. 또한 수은(I)과 수은(II) 이온이 공존하는 수용액 중의 수은(II) 이온의 분석과정에서 수은(I) 이온의 방해 효과는 관찰되지 않았다. 이를 바탕으로 하여 루미놀 화학발광 시스템을 이용하여 수용액 중의 수은(II) 이온만 선택적으로 분석하는 것이 가능하다는 결과와 함께 화학발광분석법과 ICP분석법으로부터 얻은 실험결과를 비교하여 수용액 내에 존재하는 수은 이온의 산화수별 농도를 확인할 수 있다. 루미놀 화학발광 시스템의 최적 분석조건 하에서, 수용액 중의 선택적 수은(II) 이온의 정량분석을 위해 얻은 검정곡선에서 직선성이 성립하는 농도범위는 <TEX>$1.25{\times}10^{-5}{\sim}2.50{\times}10^{-3}M$</TEX>이며, 이때 상관계수는 0.991이고, 검출한계는 <TEX>$1.25{\times}10^{-7}M$</TEX>이었다. A selective determination method of mercury (II) ion in aqueous solution by luminol-based chemiluminescence system (luminol CL system) has been developed. Determination of metal ions such as copper (II), iron (III), chromium (III) ion in solution by the luminol CL system using its catalytic role in the reaction of luminol and hydrogen peroxide has been reported by several groups. In this study, the catalytic activity of mercury (II) ion in the reaction of luminol and hydrogen peroxide was observed by the enhanced CL intensity of the luminol CL system. Based on this phenomenon, experimental conditions of the luminol CL system were investigated and optimized to determine mercury (II) ion in aqueous solution. While mercury (II) ion in mixed sample solution containing mercury (I) and (II) ions highly enhanced the CL intensity of the luminol CL system, the mercury (I) ion could not enhanced the CL intensity. Thus selective determination of the mercury (II) ions in a mixture containing mercury (I) and (II) ions could be achieved. Each concentration of mercury (I) and (II) ions in aqueous solution can be obtained from the results of the CL method that give the concentration of only mercury (II) ion and the inductively coupled plasma (ICP) method that give the total concentration of mercury ions. On the optimized conditions, the calibration curve of mercury (II) ion was linear over the range from <TEX>$1.25{\times}10^{-5}$</TEX> to <TEX>$2.50{\times}10^{-3}M$</TEX> with correlation coefficient of 0.991. The detection limit of mercury (II) ion in aqueous solution was calculated to be <TEX>$1.25{\times}10^{-7}M$</TEX>.

Label-free fluorescent sensor for mercury(ii) ion by using carbon nanotubes to reduce background signal

A simple, selective and sensitive turn-on fluorescent sensor for the detection of mercury(II) ion was developed using Sybr Green I as the signal reporter and SWCNTs as the quencher. Due to the affinity of SWCNTs towards ssDNA and organic dye, Sybr Green I, thymine-rich ssDNA and SWCNTs could form a self-assembly of three components, resulting in fluorescence quenching. Upon addition of another thymine-rich ssDNA and mercury(II) ion, formation of dsDNA via T-Hg(2+)-T base pairs enabled Sybr Green I to intercalate into the dsDNA, resulting in the restoration of fluorescence. SWCNTs were found to reduce the background signal and improve the analytical sensitivity. A linear relationship between the fluorescence intensity and the concentration of mercury(II) ion was observed in the range of 20-1250 nM (R = 0.9985) with a detection limit of 7.9 nM. The proposed method was applied to detect mercury(II) ion in tap water samples with good results.

A new fluorogenic chemodosimetric system for mercury ion recognition

A new probe system for fluorogenic sensing of mercury ions has been designed and synthesized. It is the first intermolecular reaction-based fluorogenic chemodosimetric probe system for Hg(II) ion recognition. High and low concentrations of mercury ions gave different fluorescence responses that could easily be distinguished by the naked eye. This unique system allows detection of the concentration and presence of the mercury ion.

Therapeutic potential of N-acetyl cysteine with antioxidants (Zn and Se) supplementation against dimethylmercury toxicity in male albino rats

Mercury (Hg) is currently one of the most prevalent pollutants in the environment. Many studies have examined its effects on the health of both humans and animals. Experimental studies have shown that sulfur-containing nutrients play an important role as detoxification and protecting cell against the detrimental properties of mercury. The present study was undertaken to elucidate the toxicity induced by dimethylmercury in male rats through the activities of transaminases, alkaline phosphatase, lactate dehydrogenase in serum and oxidative damage as acetyl cholinesterase activity in different regions of brain and lipid peroxidation, reduced glutathione content, mean DNA damage in liver, kidney and brain of rats given dimethylmercury (10 mg/kg, p.o., once only) along with combination therapy of N-acetyl cysteine (2 mM/kg, i.p.), zinc (2 mM/kg, p.o.) and selenium (0.5 mg/kg, p.o.) for 3 days. In the dimethylmercury group, activities of transaminases, alkaline phosphatase, lactate dehydrogenase in serum, level of lipid peroxidation, mean DNA damage and mercury ion concentration were significantly higher whereas reduced glutathione content and the activity of acetyl cholinesterase were significantly lower compared to controls ( P ≤ 0.05). Combined treatment of zinc and selenium with N-acetyl cysteine to dimethylmercury-exposed rats showed a substantial reduction in the levels of DMM-induced oxidative damage and comet tail length. In conclusion, the results of this study support that the supplementation of zinc and selenium with N-acetyl cysteine can improve the DMM induced blood and tissue biochemical oxidative stress and molecular alterations by recoupment in mean DNA damage.

1-Pyrenecarboxaldehyde thiosemicarbazone: A novel fluorescent molecular sensor towards mercury (II) ion

A novel and simple fluorescent molecular sensor, 1-pyrenecarboxaldehyde thiosemicarbazone (Hpytsc), was synthesized. Its higher sensitivity and selectivity to mercury (II) ion were studied through absorption and emission channels. The UV–vis spectra show that the increasing mercury (II) ion concentrations result in the decreasing absorption intensity. The fluorescence monomer emission of Hpytsc is enhanced upon binding mercury (II) ion, which should be due to the 1:1 complex formation between Hpytsc and metal ion.

A selective fluorescence probe for mercury ion based on the fluorescence quenching of terbium(III)-doped cadmium sulfide composite nanoparticles

A fluorescent probe for mercury(II) ions, based on the quenching of fluorescence of terbium(III) ions doped in CdS nanoparticles, has been developed. The terbium(III)-doped cadmium sulfide composite nanoparticles were successfully synthesized through a straightforward one-pot process, with the biomolecule glutathione (GSH) as a capping ligand. In addition, the terbium(III) ions were observed an enhancement of emission intensity, owing to fluorescence energy transfer from the excited CdS particles to the emitting terbium(III). Because of a specific interaction, the fluorescence intensity of terbium(III)-doped CdS particles is obviously reduced in the presence of mercury(II) ions. The fluorescence quenching phenomenon of terbium(III) can be attributed to the fact that the energy transfer system was destroyed by combining with mercury(II). Under the optimal conditions, the fluorescent intensity of terbium(III) ions at 491 nm decreased linearly with the concentration of mercury(II) ions ranging from 4.5 nmol L −1 to 550 nmol L −1. The limit of detection for mercury(II) was 0.1 nmol L −1. This method is simple, practical, relatively free of interference from coexisting substances and can be successfully applied to the determination of mercury(II) ions in real water samples. In addition, the probable mechanism of reaction between terbium(III)-doped CdS composite nanoparticles and mercury(II) was also discussed.

Protective Role of Thiol Chelators Against Dimethylmercury Induced Toxicity in Male Rats

The present study was undertaken to establish mode of action, comparative therapeutic efficacy and safety evaluation of N-acetyl cysteine and dithiothreitol against acute dimethylmercury poisoning in rats. Male Sprague-Dawley albino rats (150 +/- 10 g) were randomly divided into six groups. Group 1 served as control. Group 2-4 were administered dimethylmercury (10 mg/kg, p.o.) once only and group 2 served as experimental control. Animals of group 3 and 4 were received N-acetyl cysteine and dithiothreitol. Compared to the control, significant increase (p < or = 0.05) was observed in the activities of aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, lipid peroxidation level and mercury ion concentration, however reduced glutathione, catalase, adenosine triphosphatase, acetyl cholinesterase (in brain only) were also decreased. It was concluded that N-acetyl cysteine provided maximum protection when compared with dithiothreitol group.

A facile synthesis of Ag nanoparticles for mercury ion detection with high sensitivity and selectivity

A facile one-step synthesis of Ag nanoparticles (NPs) with particle sizes less than 5 nm is presented. The average size, size distribution and morphology of the NPs were determined using a number of techniques, including UV-visible absorption spectroscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy (EDX) and a particle size analyzer (PSA). Furthermore, the resulting Ag NPs, without extra treatment, could be used as a probe to detect Hg(II) ions in aqueous media. The response in absorbance was linearly proportional to the concentration of mercury ions in the range 0.2–3 nM. Unlike some recent reports, this absorbance-based detection scheme does not require surface modification of the NPs or oligonucleotides as targeting elements, or complicated detection systems. The method is very simple yet highly sensitive, with an observed detection limit down to 0.2 nM. Most other common ions, at 100-fold higher concentrations, have little interfering effect on the mercury ion detection.