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Indirect voltammetric determination of thiomersal in influenza vaccine using photo-degradation and graphene quantum dots modified glassy carbon electrode
摘要： Thiomersal is an organomercury derivative that degrades producing thiosalicylic acid, dithiobenzoic acid and ethylmercury. It is widely used in topical pharmaceutical preparations and as preservative in vaccines and cosmetics. In this work, an electro-analytical method for thiomersal was developed using graphene quantum dots (GQDs) as a surface modifier of a glassy carbon electrode. The method rely on using square-wave voltammetry and exploring the synergistic effect between GQDs, visible radiation and the applied potential in producing very intense Hg oxidation peak during the anodic scan. A linear voltammetric response was obtained for the analyte in the concentration range from 3.0 μmol L-1 (1.2 μg mL-1) to 32 μmol L-1 (12 μg mL-1), with a detection limit of 0.9 m mol L-1 (0.34 m g mL-1). The proposed method was successfully applied for thiomersal determination in influenza vaccine.
关键词： Voltammetry,Graphene quantum dots,Mercury,Thiomersal,Influenza vaccine,Modified glassy carbon
更新于2025-09-23 15:19:57
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Efficient “Ratiometric” fluorescence chemosensor for selective detection of Hg2+ ions based on phosphonates: its live cell imaging and molecular keypad lock applications
摘要： We report that the smart chemosensors (L1 and L2) can detect Hg2+ ion selectively over other metal ions was studied by various spectral techniques. Particularly, the proposed chemosensors exhibiting the notable color and spectra changes with the addition of mercury ions. Moreover, the colorimetric and fluorescence could be reversed with the addition of EDTA into the L1-Hg2+ and L2-Hg2+ solutions. Based on the admirable reversibility process, we displayed a molecular-scale sequential information processing circuit proposed the “Writing-Reading-Erasing-Reading” and “Multi-write” behaviors in the form of binary logic. Furthermore, L1 and L2 mimic as a molecular keypad lock and molecular logic gates with the successive addition of Hg2+ and EDTA. The binding ability of Hg2+ ion with L1 and L2 was further demonstrated by Density Functional Theory (DFT) studies. The biocompatibility of these chemosensors is successfully used for live cell imaging of Hg2+ in HeLa cells under the experimental conditions. Furthermore, the sensors L1 and L2 were also useful to determine the concentration of Hg2+ ion in real water samples to exhibit its practical applications.
关键词： Cell imaging,Molecular keypad lock,Chemosensors,Turn-off Fluorescence,Mercury (II),Logic gates
更新于2025-09-19 17:15:36
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<i>Ab initio</i> quantum-chemical computations of the absorption cross sections of HgX <sub/>2</sub> and HgXY (X, Y = Cl, Br, and I): molecules of interest in the Earth's atmosphere
摘要： The electronic-structure properties of the low-lying electronic states and the absorption cross sections (σ(E)) of mercury halides HgCl2, HgBr2, HgI2, HgBrCl, HgClI, and HgBrI have been determined within the UV-vis spectrum range (170 nm ≤ λphoton ≤ 600 nm) by means of the DKH3-MS-CASPT2/SO-RASSI quantum-chemical methodology (with the ANO-RCC basis set) and a semi-classical computational strategy based on nuclear sampling for simulating the band shapes. Computed band energies show a good agreement with the available experimental data for HgX2 with errors around 0.1–0.2 eV; theoretical and σ(E) are within the same order of magnitude. For the mixed HgXY compounds, the present computed data allow us to interpret previously proposed absorption bands estimated from the spectra of the parent molecules HgX2 and HgY2, measured in methanol solution. The analyses performed on the excited-state electronic structure and its changes around the Franck–Condon region provide a rationale on the singlet–triplet mixing of the absorption bands and the heavy-atom effect of the Hg compounds. Furthermore, the present benchmark of HgX2 and HgXY absorption σ values together with the previous benchmark of the electronic-structure properties of HgBr2 [see S. P. Sitkiewicz, et al., J. Chem. Phys., 2016, 145, 244304] has been helpful to set up a methodological and computational protocol which shall be used for predicting the atmospheric absorption and photolysis properties of several Hg compounds present in the atmospheric cycle of Hg.
关键词： semi-classical approach,quantum-chemical computations,Earth's atmosphere,UV-vis spectrum,spin-orbit coupling,mercury halides,absorption cross sections
更新于2025-09-19 17:15:36
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Rapid determination of mercury in dust emission using Cold Vapour Inductively Coupled Plasma Optical Emission Spectrometer (CV ICP OES)
摘要： Mercury emissions generated by the human activities were ranged between 60% and 90% from total mercury content determined in some industrialised regions. It is well known that urban dust has adverse health effects, being related to respiratory diseases. In this study, Cold Vapour Inductively Coupled Plasma Optical Emission Spectrometer (CV ICP OES) was optimised, validated, and applied in routine analysis for the determination of vapour mercury in dust emission samples collected from different Egyptian cement plants. The estimated detection limit, practical quantification limit, linearity (linear dynamic ranges and method linearity), accuracy (trueness and precision), and measurement uncertainty parameters were studied under optimised (CV ICP OES) conditions. The method showed that the estimated detection limit was found to be equal to 0.12 μg/L, and the quantification limit was found to be equal to 0.5 μg/L. The mean recoveries ± standard deviations at different levels were varied between 88.60 ± 8.18 and 110.20 ± 5.93% with a coefficient of variation expressed as relative standard deviation ranged from 0.64 and 7.25%. The method trueness was confirmed by using four different certified references materials purchased from Food Analysis Performance Assessment Scheme (FAPAS) and all obtained results were within satisfactory ranges and had acceptable recovery and Z-score values. The method precision, in terms of relative standard deviation (RSD), was being below 7.74%. The method uncertainty expressed as expanded uncertainty was found to be ≤ 16.11%. The results obtained make the method suitable for accurate determination of vapour mercury in dust emission samples at low concentration. The validated method was used for the determination of mercury in fifty-eight dust emissions samples and the results were compared with the maximum limit stated by European standard on the incineration of waste.
关键词： CV ICP OES,cement plants,mercury,Method validation,Egypt
更新于2025-09-19 17:13:59
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A phenobarbital containing polymer/ silica coated quantum dot composite for the selective recognition of mercury species in fish samples using a room temperature phosphorescence quenching assay
摘要： An analytical procedure using low-cost instrumentation (fluorescence/phosphorescence spectrophotometer) has been developed to assess total mercury in fishery products. Determinations were based on the room temperature phosphorescence (RTP) quenching of a composite Ph-QDs consisting of phenobarbital-containing polymer/silica coated Mn-doped ZnS quantum dots. Under optimum conditions (fish extract pH of 8.0, Ph-QDs concentration of 20 mg L?1, and an interaction time of 12 min), the material offers high selectivity for inorganic mercury and methyl-mercury over other common ions present in the fish matrix. Moreover, good linearity was obtained for mercury concentrations within the 0–100 μg L?1 range, and the obtained limit of detection (68.2 μg kg?1) is low enough for a reliable assessment of total mercury in fish and seafood samples. The developed method was found to be free of matrix effects, and offers the advantage that the fish extracts can be directly analysed even at a 1:10 dilution. The method was found to be accurate after analysing a fish certified reference material, and after comparing total mercury levels in a set of fish samples analysed by the proposed chemosensor probe and by inductively coupled plasma mass spectrometry after an acid decomposition sample pre-treatment.
关键词： Room temperature phosphorescence,Phenobarbital,Fish,Mercury,Quantum dots
更新于2025-09-19 17:13:59
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Long-Term Comparison of Attraction of Flying Insects to Streetlights after the Transition from Traditional Light Sources to Light-Emitting Diodes in Urban and Peri-Urban Settings
摘要： Among the different light sources used for street lighting, light-emitting diodes (LEDs) are likely to dominate the world market in the coming years. At the same time, the spectral composition of nocturnal illumination is changing. Europe and many other areas worldwide have implemented bans on energy-inefficient lamps, such as the still very common mercury vapor lamps. However, the impact of artificial light on insects is mostly tested with light-traps or flight-intercept traps that are used for short periods only. By comparing the numbers of insects attracted by street lamps before and after replacing mercury vapor light sources (MV) with light emitting diodes, we assessed the impact in more typical (urban and peri-urban) settings over several years. We found that LED attracted approximately half of the number of insects compared to MV lights. Furthermore, most insect groups are less drawn by LED than by MV, while Hymenoptera are less attracted by MV than by LED. Thus, the composition of the attracted communities differed between the light sources, which may impact ecosystem processes and functions. In green peri-urban settings more insects are attracted than in an urban setting, but the relative difference between the light sources is the same.
关键词： artificial light,LED,moths,mercury vapor,Hymenoptera,Lepidoptera,phototaxis
更新于2025-09-16 10:30:52
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A New Plant Indicator ( <i>Artemisia lavandulaefolia</i> DC.) of Mercury in Soil Developed by Fourier-Transform Near-Infrared Spectroscopy Coupled with Least Squares Support Vector Machine
摘要： A rapid indicator of mercury in soil using a plant (Artemisia lavandulaefolia DC., ALDC) commonly distributed in mercury mining area was established by fusion of Fourier-transform near-infrared (FT-NIR) spectroscopy coupled with least squares support vector machine (LS-SVM). The representative samples of ALDC (stem and leaf ) were gathered from the surrounding and distant areas of the mercury mines. As a reference method, the total mercury contents in soil and ALDC samples were determined by a direct mercury analyzer incorporating high-temperature decomposition, catalytic adsorption for impurity removal, amalgamation capture, and atomic absorption spectrometry (AAS). Based on the FT-NIR data of ALDC samples, LS-SVM models were established to distinguish mercury-contaminated and ordinary soil. The results of reference analysis showed that the mercury level of the areas surrounding mercury mines (0–3 kilometers, 7.52–88.59 mg/kg) was significantly higher than that of the areas distant from mercury mines (>5 kilometers, 0–0.75 mg/kg). The LS-SVM classification model of ALDC samples was established based on the original spectra, smoothed spectra, second-derivative (D2) spectra, and standard normal transformation (SNV) spectra, respectively. The prediction accuracy of D2-LS-SVM was the highest (0.950). FT-NIR combined with LS-SVM modeling can quickly and accurately identify the contaminated ALDC. Compared with traditional methods which rely on naked eye observation of plants, this method is objective and more sensitive and applicable.
关键词： soil,LS-SVM,FT-NIR spectroscopy,Artemisia lavandulaefolia DC.,mercury
更新于2025-09-16 10:30:52
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Sulfur and nitrogen coa??doped graphene quantum dota??assisted chemiluminescence for sensitive detection of tryptophan and mercury (II)
摘要： A simple one-step thermal treatment to prepare strong fluorescent sulfur and nitrogen co-doped graphene quantum dots (SN-GQD) using citric acid and L-cysteine as precursors was developed. The ultra-weak chemiluminescence (CL) from the reaction of hydrogen peroxide (H2O2) and periodate (IO4?) was significantly enhanced by SN-GQD in acidic medium. The enhanced CL was induced by excited-state SN-GQD (SN-GQD*), which was produced from the transfer energy of (O2)2* and 1O2 to SN-GQD and recombination of oxidant-injected holes and electrons in SN-GQD. In the presence of tryptophan (Trp), the CL intensity of the SN-GQD–H2O2–KIO4 system was greatly diminished. This finding was used to design a novel method for determination of Trp in the linear range 0.6–20.0 μM, with a limit of detection (LOD) of 58.0 nM. Furthermore, Hg2+ was detectable in the range 0.1–9.0 μM with a LOD of 64.0 nM, based on its marked enhancement of the SN-GQD–H2O2–KIO4 CL system. The proposed method was successfully applied to detect Trp in milk and human plasma samples and Hg2+ in drinking water samples, with recoveries in the range 95.7–107.0%.
关键词： tryptophan,S,N co-doped graphene quantum dots,chemiluminescence,mercury (II)
更新于2025-09-16 10:30:52
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Electrochemical sensing of mercury ions in electrolyte solutions by nitrogen-doped graphene quantum dot electrodes at ultralow concentrations
摘要： Electrochemical detection of mercury ions in aqueous solution was investigated at indium tin oxide (ITO) conducting glass electrode modified by nitrogen-doped graphene quantum dots (N-doped GQDs). The N-doped GQDs with an average particle size of 4.5 nm were synthesized through an infrared-assisted pyrolysis of citric acid and urea at 250°C. The GQD sample contains high oxidation and amidation level, i.e., O/C and N/C atomic ratios: 37.6% and 30.7%, respectively. The electrochemical sensing toward Hg2+ ions was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Based on the CV and EIS analyses, both the reductive and oxidative peak currents as well as the equivalent series resistance demonstrate a decreasing trend with increased Hg2+ concentration. The detection limit of N-doped GQD/ITO electrodes toward Hg2+ ions reached 10 ppb with the accumulation time of 32 s. The GQD/ITO electrodes also exhibit superior selectivity toward the target contaminant (i.e. Hg2+ ion). Accordingly, the functionalized GQDs pave the way for engineering the electrochemical sensors capable of detecting toxic Hg2+ ions with superb sensitivity and selectivity.
关键词： Nitrogen doping,Electrolyte solution,Infrared-assisted synthesis,Graphene quantum dots,Mercury ions
更新于2025-09-16 10:30:52
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Genetically encoded FRET-based optical sensor for Hg2+ detection and intracellular imaging in living cells
摘要： Due to the potential toxicity of mercury, there is an immediate need to understand its uptake, transport and flux within living cells. Conventional techniques used to analyze Hg2+ are invasive, involve high cost and are less sensitive. In the present study, a highly efficient genetically encoded mercury FRET sensor (MerFS) was developed to measure the cellular dynamics of Hg2+ at trace level in real time. To construct MerFS, the periplasmic mercury-binding protein MerP was sandwiched between enhanced cyan fluorescent protein (ECFP) and venus. MerFS is pH stable, offers a measurable fluorescent signal and binds to Hg2+ with high sensitivity and selectivity. Mutant MerFS-51 binds with an apparent affinity (Kd) of 5.09 × 10?7 M, thus providing a detection range for Hg2+ quantification between 0.210?μM and 1.196?μM. Furthermore, MerFS-51 was targeted to Escherichia coli (E. coli), yeast and human embryonic kidney (HEK)-293T cells that allowed dynamic measurement of intra- cellular Hg2+ concentration with a highly responsive saturation curve, proving its potential application in cellular systems.
关键词： Genetically encoded,FRET,Fluorescent proteins,Mercury,Nanosensors
更新于2025-09-11 14:15:04