Mercury Sensitivity Research Articles

Novel optical microcapsule sensor for effective recognition of Hg(II) and Ag(I) ions in the aquatic environments

Because conventional methods for the detection of heavy metal ions in water involve expensive equipment and complex procedures, there is a lot of interest in the improvement of simple and quick methods for determining heavy metal ions in water. Use of natural polymers as biosorbents such as sporopollenin for heavy metal removal is advantageous. There is an urgent demand to devise a simple method for the simultaneous detection of metal ions, especially in the case of mercury(II) and silver(I) coexisting among metals. Therefore, in this study, a fluorescent microcapsule sensor (SpT-P[5]-EB), the modified sporopollenin surface based-on a combination of Pillar[5]arene and Bodipy, was developed to detect silver(I) and mercury(II) ions simultaneously or separate with an “on-off” principle in the aquatic environment. The fluorescent microcapsule, SpT-P[5]-EB, indicated a high sensitivity and excellent selectivity for both silver(I) and mercury(II) ions with detection limits of 1.51 µM and 0.72 µM, respectively. The Hg(II) and Ag(I) ions may be detected simultaneously or individually using the SpT-P[5]-EB microcapsule sensor in easy, practical, and affordable procedures.

Detecting dissolved mercury(ii) ions using chitosan-AgNP strips integrated with smartphones.

A simple preparation of a paper strip test with a smartphone-based instrument for detecting dissolved mercury is still in development. This study aims to develop a smartphone-based colorimetric paper strip test using chitosan-stabilized silver nanoparticles for detecting dissolved mercury. The method demonstrated high sensitivity and selectivity for Hg2+ ions, with detection limits comparable to UV-vis spectrophotometry. Silver ions embedded in the chitosan matrix were reduced by either sodium NaBH4 or N2H4. Both chi-AgNP colloidal and chi-AgNP paper strips were tested for sensitivity of mercury(ii) solution detection with and without ion interference. The accuracy of colour change responding to the mercury concentration was recorded with several smartphones in a handmade cubical and a T-shape micro-studio. Only NaBH4 gives colloidal chi-AgNPs relatively dispersed, and the colloidal chi-AgNPs become aggregated when AgNP interacts with mercury(ii) ions. The colour change of chi-AgNP paper strips responding to the concentration of mercury(ii) and quantified using a smartphone is consistent when confirmed with UV-vis spectrophotometric determination with a comparable limit of detection (0.76 μM). The inferring ions do not significantly affect mercury(ii) analyses. Therefore, the paper strip integrated with the smartphone is effectively used for mercury(ii) detection in water as long as the mercury concentration is >1 μM. This finding might inspire advanced technology with a larger number of data references, and machine learning involvement to develop more compatible and simple mercury detection.

Toxic heavy metal/oxyanion tolerance in haloarchaea from some saline and hypersaline ecosystems.

Toxic heavy metal/oxyanion contamination has increased severely through the last decades. In this study, 169 native haloarchaeal strains were isolated from different saline and hypersaline econiches of Iran. After providing pure culture and performing morphological, physiological, and biochemical tests, haloarchaea resistance toward arsenate, selenite, chromate, cadmium, zinc, lead, copper, and mercury were surveyed using an agar dilution method. On the basis of minimum inhibitory concentrations (MICs), the least toxicities were found with selenite and arsenate, while the haloarchaeal strains revealed the highest sensitivity for mercury. On the other hand, the majority of haloarchaeal strains exhibited similar responses to chromate and zinc, whereas the resistance level of the isolates to lead, cadmium, and copper was very heterogeneous. 16 S ribosomal RNA (rRNA) gene sequence analysis revealed that most haloarchaeal strains belong to the Halorubrum and Natrinema genera. The obtained results from this study showed that among the identified isolates, Halococcus morrhuae strain 498 had an exceptional resistance toward selenite and cadmium (64 and 16 mM, respectively). Also, Halovarius luteus strain DA5 exhibited a remarkable tolerance against copper (32 mM). Moreover, strain Salt5, identified as Haloarcula sp., was the only strain that could tolerate all eight tested heavy metals/oxyanions and had a significant tolerance of mercury (1.5 mM).

Novel magnetic covalent organic framework loaded ligand for rapid removal and selective detection of mercury(II) from water

The present work aimed to prepare a novel magnetic covalent organic framework loaded ligand (MCM), which is going to be utilized to obtain efficient adsorption, rapid removal, and detection with high selectivity and sensitivity for mercury(II) ions. The structure, morphology, adsorption behavior, and detection properties of MCM were characterized with FTIR, TG, XRD, BET, SEM, TEM, UV-VIS, and XPS. To optimize the effects of process parameters, the influence of pH, contact time, and initial concentration on the adsorption behavior, color optimization, and detection limit of the mercury(II) ions was investigated. Under the optimal condition, MCM showed the efficient adsorption ability, rapid removal rate, high selectivity, and detection with excellent sensitivity for the mercury(II) ions. The color of MCM changed from light grey to yellow by observing with naked-eye in the presence of the mercury (II) ions, and the corresponding detection limit was 0.01μg/L. MCM also has a high removal rate of mercury (II) ions in industrial wastewater, which can meet the industrial discharge standard (residual concentration of mercury(II) ions in the solution is 0.05 mg/L). What's more, MCM could be used in a portable column unit to separate mercury(II) ions from actual water samples, rapidly reducing the mercury(II) concentration from 10.0 mg/L to 10.0 μg/L within 15 s. Kinetic studies showed that the MCM adsorption behavior for mercury(II) ions was in good agreement with the pseudo-second-order model, and the MCM adsorption equilibrium data for mercury(II) ions belonged to the Langmuir model. Furthermore, the adsorption amount of MCM for mercury(II) ions after five adsorptions was 96.89% of the adsorption amount of MCM for the first adsorption of mercury(II) ions, which showed that MCM has good regeneration ability. Consequently, MCM provided an excellent alternative to mercury(II) ions adsorption or enrichment materials, and this method showed great potential in the routine monitoring of trace mercury(II) ions in liquid substrates.

Catalytic oxidation of O-phenylenediamine by silver nanoparticles for resonance Rayleigh scattering detection of mercury (II) in water samples

In this study, a facile nanoparticle catalytic sensor for resonance Rayleigh scattering quantification of mercury (II) ion was developed. The developed approach is relied on the selective inhibition of the peroxidase-like activity of polyvinylpyrrolidone-stabilized silver nanoparticles (PVP-Ag-NPs) by mercury (II) ions. The synthesized PVP-Ag-NPs oxidize the aqueous solution of O-Phenylenediamine (colorless) to 2,3-phenazinediamine (bright yellow) and their resonance Rayleigh scattering (RRS) activity was completely suppressed. When mercury (II) was introduced, the RRS activity of PVP-Ag-NPs was turned on combined with a reduction of the intensity of the yellow color. The enhancement in the RRS intensity was related to the concentration of mercury (II) in the linear range of 10–2000 nM. The smaller size (4.5 nm), the large surface area and the uniform size (PDI = 0.379) of the synthesized PVP-Ag-NPs offered a higher chance for interaction between mercury (II) and PVP-Ag-NPs with the advantages of high sensitivity (LOD = 4 nM) and excellent selectivity for mercury (II) detection over several metals and anions.

Electrochemical Behaviour of Real-Time Sensor for Determination Mercury in Cosmetic Products Based on PANI/MWCNTs/AuNPs/ITO

Mercury is a common ingredient found in skin lightening soaps, creams, and makeup-cleansing products. It may cause skin rashes, skin discolouration, and scarring, as well as a reduction in the skin’s resistance to bacterial and fungal infections. By looking at this scenario, developing a sensor that involved a simple procedure and fasts for real-time detection without affecting mercury sensitivity is urgently needed. For that reason, a fast and sensitive electrochemical method was developed to determine mercury in cosmetic products with the composition of polyaniline/multi-walled carbon nanotubes/gold nanoparticles/indium tin oxide sheet using methylene blue as a redox indicator. The significantly enhanced electrochemical performance was observed using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). In order to detect mercury qualitatively and quantitatively, deposition potential and deposition time were respectively optimised to be 0.10 V and 70 s. The modified sensor was revealed a wide detection range of mercury from 0.01 to 10.00 ppm with a limit of detection of 0.08 ppm. The modified sensor towards mercury with a correlation coefficient (r2) was of 0.9948. Multiple cycling, reproducibility, and consistency of different modified sensors were investigated to verify the modified sensor’s performance. The developed sensing platform was highly selective toward mercury among the pool of possible interferents, and the stability of the developed sensor was ensured for at least 21 days after 10 repeated uses. The proposed method is a fast and simple procedure technique for analysing the mercury levels in cosmetic products.

Sensitive and selective determination of trace amounts of mercury ions using a dimercaprol functionalized graphene quantum dot modified glassy carbon electrode.

A novel nanomaterial is synthesized based on the functionalization of graphene quantum dot with dimercaprol (GQD-DMC). Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (TEM) are used to approve the successful synthesis of GQD-DMC. The synthesized nanomaterial is used as an electrode modifier for the sensitive and selective determination of mercury(ii) ions in real water samples. The method of evaluation is based on the pre-concentration of mercury ions on the GQD-DMC modified glassy carbon electrode, reduction of Hg(ii), and anodic stripping voltammetric measurement of these reduced ions in a buffer solution. The pre-concentration of mercury ions is driven by the affinity interaction between the surface containing functional groups of DMC and Hg(ii) ions. The GQD-DMC modified glassy carbon electrode (GQD-DMC/GCE) shows extra sensitivity and selectivity for mercury(ii) detection, which is assumed to be due to the increased surface area as well as the presence of sulfur-containing functional groups on the modified structure.

Diagnostics of Environmental Risks and Mapping of Surface Water Sensitivity Due to Metal Contamination from Artisanal Gold Mining in Côte d’Ivoire: Case of Angovia, Kokumbo, Hireand Agbaou

The present study performed on the Angovia, Kokumbo, Hire and Agbaou sites consisted of mapping the environmental risks linked to artisanal gold mining activities in C?te d’Ivoire. An inventory was done by observing the different phases of gold extraction and identifying the risks associated with these phases. Using a Geographic Information System (GIS), the representation of the spatial distribution of the pollution risks has been realized from indicator descriptives of the environmental sensitivity (i.e. slope, proximity to the watercourse, soil cover) and the transfer indicator (i.e. rainfall). The analysis of this map showed low sensitivity of mercury (Hg), arsenic (As), copper (Cu) and zinc (Zn) measured in the waters of the Hire and Agbaou localities, while moderate sensitivity in Kokumbo surface waters and high sensitivity for those of Angovia locality were observed. Moreover, analysis of Hg, As, Cu and Zn content spatial distribution maps in surface waters revealed that Hg and As come mainly from the artisanal mining activities for most localities. Among these metallic trace elements observed, only the Hg content was above the WHO Limit Values, 1994 (>0.001 mg·L-1). The continuous spread of metallic trace elements in surface water can pose serious health problems for people living around artisanal gold mining sites, hence the need to put in place a protection plan against contamination.

Mercury accumulation and transformation of main leaf vegetable crops in Cambosol and Ferrosol soil in China.

Leaf vegetables serve as an important food for the local residents in China. This paper focuses on the uptake, accumulation, transfer, and mercury (Hg) sensitivity of leafy vegetables. Two types of soil (an alkaline Cambosol and an acid Ferrosol) and eleven species of leafy vegetable, namely, Spinach, Tung choy, Leek, Fennel, Coriander, Chinese flowering cabbage, Wuta-tsai, Pakchoi, Chicory, Crown daisy, and Lettuce, were selected to investigate their sensitivity to Hg accumulation in a greenhouse pot experiment. Three Hg concentration treatments were carried out as control (background values), low concentration (1.5 times standard value), and high concentration (2 times standard value) as adjusted by the soil pH. Hg concentrations of more than half vegetable samples grown in Cambosol (collected from Shandong Province) reached or exceeded the maximum permissible food safety levels (10 μg kg-1) according to the General Standard of Contaminants in Food in China (GB 2762-2012), while only about 15% in Ferrosol (collected from Jiangxi Province). Meanwhile, Hg bio-concentration factors (BCF) in all treatments were < 1, while Hg translocation factors (TF) in most treatments were < 1. Correlation analysis among soil, root, and edible plant parts revealed that the principal source of Hg in leafy vegetables was most likely from Hg-contaminated soils. Species sensitivity distribution (SSD) models were constructed and their simulated curves indicated that sensitivity to Hg was highest in Pakchoi in low Hg-contaminated soils, and Chicory in highly Hg-contaminated soils. Therefore, Hg concentration is mostly accumulated in roots of leafy crops, which reduces the risk of Hg bioaccumulation in edible portion of vegetables, and (2) Brassicaceae vegetables are mostly less sensitive to soil Hg contamination. Our results provide effective guidance for the selection of leafy vegetables for cultivation and daily consumption that minimizes health risk.

Feedback regulation mode of gene circuits directly affects the detection range and sensitivity of lead and mercury microbial biosensors

Whole cell biosensors offer high potential for the detection of heavy metals in a manner that is simple, rapid and low-cost. However, previous researchers have paid little attention to the impacts of construction models on the performance of these biosensors, thereby limiting the achievement of rational design and the optimization of detection characteristics. Herein, for the first time, three basic models of lead and mercury detection circuits, namely feedback coupled, uncoupled and semi-coupled models, have been constructed and compared to explore the effects of uncoupling the topology of sensing circuits on the reporter signals. The results demonstrated that the uncoupled model had better sensitivity for both lead (50 nM) and mercury (1 nM), while the feedback coupled circuits had a wider detection range for mercury (10 nM - 7.5 μM). Introducing the semi-coupled model into the comparison revealed that both the type and location of promoters for regulatory protein genes were key factors for sensitivity. Moreover, the detection characteristics of the uncoupled biosensors were robust, as conditions such as induction time, the concentration of microbial cells, and the concentration of antibiotics had little interference on the performance of the microbial biosensors. This study also established a novel and simple pre-treatment method for sample detection by biosensors. When the uncoupled microbial biosensor was put into practice, the concentration levels of mercury in milk and lead in sewage were determined quickly and accurately. Our study, therefore, provides a strategy for the rational design of whole cell heavy metal biosensors and has developed the potential of their application.

The Application of Crude Ginger Protease as an Inhibitive Assay for Heavy Metals

In this work, a novel source of protease for the bioassay of heavy metals has been developed using proteases extracted from ginger. The result shows that the optimum protease activity was reached at 1 mg/mL protein concentration of the ginger protease. The optimum casein concentration toward crude ginger protease activity was 1.75 mg/mL. The most suitable pH for protease from crude ginger protease was within the range from pH 5.0 to 7.0. The proteases exhibited high protease activity in a broad range of temperature from 20 to 60 oC. The optimum incubation time for the enzyme occurred at minute 30. Among the six heavy metals tested, only three heavy metals inhibited proteolytic activity of ginger crude with an inhibition more than 30% at 1 mg/L. The calculated LC50 for mercury, copper and silver were, 0.182, (95%, confidence interval (C.I.) 0.134 to 0.283), 0.071, (95% C.I. of 0.056 to 0.096), 0.054, (95% C.I. of 0.039 to 0.085), respectively. Data on the sensitivity of various proteases to heavy metals shows that the crude ginger protease is comparable in sensitivity for mercury to the achromopeptidase, bromelain, papain assays. The crude ginger protease assay for copper is comparable in sensitivity to the papain assay and appears to be more sensitive than the rest of the assays. For silver, the ginger protease was the most sensitive while other assay methods are either unable or be able to detect higher concentration of silver. The crude proteases extracted from ginger showed a good potential for the development of a rapid, sensitive, and economic inhibitive assay for the biomonitoring of mercury, copper, and silver in the environment.

Triangular silver nanoplates as a spectrophotometric reagent for the determination of mercury(II)

The applicability of triangular silver nanoplates (TNPs) as a spectrophotometric reagent for the determination of mercury(II) in an aqueous solution was estimated. The method is based on the oxidation of TNPs with a mean edge length of 52 nm and thickness of 4 nm by mercury(II) ions, which is accompanied by a decrease in the surface plasmon resonance of nanoparticles. The effect of reaction time, pH of solution, and TNP concentration on the sensitivity of mercury(II) determination was studied. The limit of mercury(II) detection under the selected conditions was 0.022 μg/mL.

Simple synthesis of highly selective and fast Hg(II) removal polymer from aqueous solution

Among the toxic metals, mercury (Hg) is a highly toxic element, and hence, a suitable technology is required to remove it. An imprinted polymer exhibiting a high sensitivity for mercury (II) in aqueous solution is presented. Polymer particles imprinted with mercury (II) were synthesized by polymerizing aminothiophenol. The imprinted polymer was characterized by Fourier transform infrared spectroscopy, UV–vis spectroscopy, X-ray diffraction analysis, and scanning electron microscopy. Relative selective coefficients (k′) of the imprinted polymer evaluated from selective binding studies between Hg2+ and Cu2+ or Hg2+ and Cd2+ were 64 and 27, respectively. These values indicated highly favored Hg2+ extractions over the two competing ions. The polymer has high analytical potential for selective extraction and pre-concentration of mercury (II) ions in the presence of closely related ions. Here we report simple synthesis of polymer with high selectivity and fast adsorption capability of Hg (II) ion over similar charge cations such as Cd (II) and Cu (II). The study shows that the polymer has a potential intern of reusability and high stability.

New 'aggregation induced emission (AIE)' active cyclometalated iridium(III) based phosphorescent sensors: high sensitivity for mercury(II) ions.

Design and syntheses of 'aggregation induced emission (AIE)' active blue-emitting bis-cyclometalated iridium(III) complexes with appended diphosphine ligands [Ir(F2ppy)2(L1/L2)2(Cl)] (F2ppy = 2-(2',4'-difluoro) phenylpyridine; L1 = 1,2-bis(diphenylphosphino)ethane; L2 = bis(diphenylphosphino)propane) have been realized on a suitable route. The free phosphorous donor atom present on the appended diphosphine is shown to provide selective binding to the mercuric ion (Hg(2+)). The selective binding ability of the probe molecule towards mercuric ions results in a detectable signal due to complete quenching of their AIE properties. The quenching effect of the probe molecule has been explored and found to be the result of the degradation of the probe iridium(III) complex triggered by the presence of mercuric ions due to an interplay of a soft-soft interaction between the free phosphorous atom of the probe molecule and mercuric ions. These complexes were modelled to obtain deeper understanding of excited state properties and the results were tentatively correlated with the experimental data.

Highly Sensitive and Selective Spectroscopic Detection of Mercury(II) in Water by Using Pyridylporphyrin–DNA Conjugates

Single-labeled pyridylporphyrin-DNA conjugates are reported as highly sensitive and selective spectroscopic sensors for mercury(II) ions in water. The effects of chemical structure (thymine versus adenine), number of nucleotides (monomer versus octamer), and porphyrin metalation (Zn versus free base) on the sensitivity and selectivity of mercury(II) detection are explored. The results indicated that pyridylporphyrin rather than the nucleobase plays a crucial role in mercury(II) sensing, because porphyrin conjugates with both adenosine and thymidine exhibited excellent mercury(II) detection. Mercury(II) recognition was shown in emission quenching, as well as in a redshift of the porphyrin Soret band absorption. The limit of detection (LOD, 3σ/slope) of zinc(II) pyridylporphyrin-5'-oligodeoxythymidine (ZnPorT8) obtained by fluorescence quenching was calculated to be 21.14 nM. Other metal cations (Zn(2+), Cd(2+), Pb(2+), Mn(2+), Ca(2+), Ni(2+), Mg(2+), Fe(2+), Cu(2+), and Na(+)) did not interfere with the emission and absorption sensing of mercury(II). Free-base porphyrin-oligothymine conjugate 2HPorT8 displayed similar sensitivity to ZnPorT8 but different selectivity. The results also implied that the sensing properties of porphyrin-deoxythymidine conjugates could potentially be tuned by porphyrin metalation.

A conserved cysteine residue is involved in disulfide bond formation between plant plasma membrane aquaporin monomers

AQPs (aquaporins) are conserved in all kingdoms of life and facilitate the rapid diffusion of water and/or other small solutes across cell membranes. Among the different plant AQPs, PIPs (plasma membrane intrinsic proteins), which fall into two phylogenetic groups, PIP1 and PIP2, play key roles in plant water transport processes. PIPs form tetramers in which each monomer acts as a functional channel. The intermolecular interactions that stabilize PIP oligomer complexes and are responsible for the resistance of PIP dimers to denaturating conditions are not well characterized. In the present study, we identified a highly conserved cysteine residue in loop A of PIP1 and PIP2 proteins and demonstrated by mutagenesis that it is involved in the formation of a disulfide bond between two monomers. Although this cysteine seems not to be involved in regulation of trafficking to the plasma membrane, activity, substrate selectivity or oxidative gating of ZmPIP1s (Zm is Zea mays), ZmPIP2s and hetero-oligomers, it increases oligomer stability under denaturating conditions. In addition, when PIP1 and PIP2 are co-expressed, the loop A cysteine of ZmPIP1;2, but not that of ZmPIP2;5, is involved in the mercury sensitivity of the channels.

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.

Activation of TRPC Cationic Channels by Mercurial Compounds Confers the Cytotoxicity of Mercury Exposure

Mercury is an established worldwide environmental pollutant with well-known toxicity affecting neurodevelopment in humans, but the molecular basis of cytotoxicity and the detoxification procedure are still unclear. Here we examined the involvement of the canonical transient receptor potential (TRPC) channel in the mercury-induced cytotoxicity and the potential detoxification strategy. Whole-cell and excised patches, Ca(2+) imaging, and site-directed mutagenesis were used to determine the mechanism of action of mercurial compounds on TRPC channels overexpressed in HEK293 cells, and cytotoxicity and preventive effect were investigated in cell culture models using small interfering RNA and pharmacological blockers. Mercury potently activates TRPC4 and TRPC5 channels. The extracellular cysteine residues (C(553) and C(558)) near the channel pore region of TRPC5 are the molecular targets for channel activation by mercury. The sensitivity of mercury to TRPC5 is presumed to be specific because other divalent heavy metal pollutants, such as Cd(2+), Ni(2+), and Zn(2+), had no stimulating effect, and TRPC3, TRPC6, TRPV1, and TRPM2 were resistant to mercurial compounds. The channel activity of TRPC5, as well as TRPC4, induced by mercury, was prevented by 2-aminoethoxydiphenyl borate and modified by a reducing environment. The inhibition of TRPC5 channels by specific TRPC5 pore-blocking antibody or by SKF-96365 alleviated the cytotoxicity, whereas the mercury chelator, meso-2,3-dimercaptosuccinic acid, showed nonselective prevention of cell survival. Silencing of the TRPC5 gene reduced the mercury-induced neuronal damage. These results indicate that mercurial compounds are activators for TRPC5 and TRPC4 channels. Blockade of TRPC channels could be a novel strategy for preventing mercury-induced cytotoxicity and neurodevelopment impairment.

Changing delayed-type sensitizations to the baseline series allergens over a decade at the Zurich University Hospital

Patch testing detects delayed-type sensitizations and may show changes in prevalence over time. To compare sensitization prevalence to our baseline series allergens during the years 2000-2004 to results from 1990 to 1994. We analysed baseline patch test series allergens from 2000 through 2004. 4094 individuals were patch tested to the baseline series (mean age 45.4 years, males 41.7%). The highest sensitization rates were found for nickel sulfate (19.3%), fragrance mix (10.4%) and Myroxylon pereirae (7.8%). Compared to 1990-1994, methylchloroisothiazolinone (and) methylisothiazoline (MCI/MI) and neomycin sulfate sensitization decreased and lanolin alcohol, thiuram mix and ammoniated mercury sensitization increased. Current sensitization rates are similar to those across Europe. Reduced sensitizations to MCI/MI and neomycin sulfate and increased sensitizations to thiuram mix and ammoniated mercury chloride may well be because of changes in exposure. The current group comprises a higher proportion affected by leg dermatitis and may thus explain the higher sensitization to lanolin alcohol. Comparing patch results over time shows important changes in sensitization prevalence.

Laser ignition assisted spark-induced breakdown spectroscopy for the ultra-sensitive detection of trace mercury ions in aqueous solutions

The trace mercury ions in aqueous solutions were electrically deposited on the surface of a high purity copper plate and then quantitatively analyzed by laser ignition assisted spark-induced breakdown spectroscopy (LI-SIBS). Laser ignition is helpful to enhance discharge stability and reduce the required voltage level in SIBS. The analysis sensitivity of mercury in LI-SIBS was enhanced by a factor of 30 in comparison with that in laser-induced breakdown spectroscopy (LIBS). A 6% relative standard deviation has been achieved in multiple measurements and the limit of detection of mercury in aqueous solutions by LI-SIBS has reached to 2μgL−1 under present experimental conditions. LI-SIBS overcomes the low-sensitivity shortcoming of LIBS on the analysis of mercury. By combining with electrical deposition enrichment, LI-SIBS provides a simple and ultra-sensitive analysis method for mercury ions in water.