Determination Of Trace Mercury Research Articles

Determination of Trace Mercury in Geological Samples by Atomic Fluorescence Spectrometry

An atomic fluorescence method was established for the determination of mercury in geological samples. After sample digestion, mercury reacts with potassium borohydride in a specific medium to produce volatile hydride. The fluorescence of characteristic wavelength is emitted under the irradiation of argon loaded quartz atomizer light source, and the fluorescence intensity is proportional to the content of elements.

Deep Eutectic Solvent Based Liquid-Liquid Microextraction of Mercury in Water, Hair and Fish with Spectrophotometric Determination: A Green Protocol

Mercury (Hg) is a toxic heavy metal discharged into the environment by many human and natural sources. Therefore, the precise and accurate determination of trace mercury in samples is of immense importance. In this regard, a spectrophotometric method has been developed for the quantification of Hg (II) in water, hair, and fish using deep eutectic (choline chloride, ChCl + decanol) solvent-based liquid-liquid microextraction (DES-LLME). All of the relevant parameters, including pH (9), volume of 1-(2-pyridylazo)-2-naphthol (PAN) (300 µL), ratio of choline chloride and decanol (1:1), volume of DES (400 µL), volume of tetrahydrofuran (THF) (400 µL), and sample volume (40 mL) were optimized. The low limits of detection (LOD) (0.09 µg L−1) and quantification (LOQ) (0.325 µg L−1) demonstrate that the developed approach is highly sensitive. High preconcentration (PF) and enhancement factors (EF) of 50 show that the developed protocol is highly efficient. The relative standard deviation (RSD) is 6.32%, indicating that the method is reproducible. The method was validated by the analysis of TMDA-53.3 water and NCSZC81002B hair certified reference materials with high recoveries of 97% and 93%, respectively. The method was also employed for the analysis of tap water, dam water, river water, hair, and tuna fish with satisfactory recoveries from 95% to 102%. The developed approach was compared with literature methods on the basis of the limit of detection.

Novel Paper-Based Fluorescent Sensor Based on N-Doped Carbon Quantum Dots (N-CQDs) and Cotton Fiber Paper (CFP) with High Selectivity and Sensitivity for the Visual Determination of Mercury (II) in Environmental Waters

A highly selective solid-state fluorescent sensor based on N-doped carbon quantum dots (N-CQDs) and cotton fiber paper (CFP) is reported for the determination of trace mercury (II)(Hg2+). The N-doped carbon quantum dots on cotton fiber paper (N-CQDs@CFP) was synthesized using a facile one-step microwave hydrothermal method. Multiple approaches were employed to fully investigate the morphology and chemical structure of the paper-based fluorescent sensor. The N-CQDs were chemically bonded onto the CFP, which offers good reproducibility and stability of the sensor. The N-CQDs@CFP showed high-intensity blue emission in dark-field imaging, and the fluorescence was quenched by Hg2+. The Hg2+ in aqueous samples was easily determined and visually monitored. There was good linearity from 0 to 250 μM, and the limit of detection was 34 nM. The paper-based fluorescent sensor provided accurate and rapid determination of Hg2+ upon comparison with flame atomic absorption spectrophotometry (FAAS). The simple preparation, rapid detection (< 5 min), low cost, and easy-handling illustrate that the reported sensor has a significant value in environmental monitoring.

Study of an adsorption method for trace mercury based on Bacillus subtilis

Abstract In order to decrease the difficulty in trace mercury determination, an adsorption method for trace mercury based on Bacillus subtilis cells was proposed in this article. The adsorption process was characterized by optical microscopy and SEM. The adsorption mechanism was analyzed by IR. The adsorption performance was studied by measuring the concentration of supernate and calculating the adsorption efficiency. When adsorbing Hg2+, Bacillus subtilis cells gathered and their structure turned coarse. The IR results illustrated that functional groups bound with Hg for complexation during adsorption. Bacillus subtilis completed adsorption for trace Hg2+ in 15 min. The adsorption efficiency was maintained above 80% under low Hg2+ concentrations (&lt;200 µg/L). The proposed study illustrates that Bacillus subtilis cells are highly efficient and easily obtained material for the adsorption of trace mercury, which shows potential to be further used in the pretreatment of trace Hg2+ detection.

Ivy extract-assisted photochemical vapor generation for sensitive determination of mercury by atomic fluorescence spectrometry

Making use of the natural plant extract as assistant matrix or photocatalyst provides an efficient strategy to break the limitation of traditional photochemical vapor generation atomic fluorescence spectrometry in efficiency, sensitivity, and biocompatibility. In this work, ivy extract-assisted photochemical vapor generation was proposed for the determination of trace mercury in natural water by atomic fluorescence spectrometry. The influencing factors such as irradiation time, irradiation wavelength and concentration of extract were systematically studied. Under the optimized experimental conditions, the limit of detection for total mercury was 0.03 ng mL−1 which is better than the ethanol- assisted photochemical vapor generation system. This method is green and sensitive, reduces the biological toxicity of photocatalytic materials and secondary pollution in the reduction process, and provides experimental basis for expanding the photochemical vapor generation system.

Thiol-grafted magnetic polymer for preconcentration of Cd, Hg, Pb from environmental water followed by inductively coupled plasma mass spectrometry detection

A novel thiol-grafted magnetic polymer (MPPs-SH) was synthesized by “click reaction” between 1,2-ethanedithiol and Fe3O4@SiO2@poly (ethylene glycol dimethacrylate -co- glycidyl methacrylate). The resultant MPPs-SH had high S content (5.4 wt%) and exhibited large specific surface area (156.8 m2 g−1) as well as high adsorption capacity of 254, 64.2, 56.6 mg g−1 for mercury, cadmium and lead ions, respectively. With the prepared MPPs-SH as sorbent, a method of magnetic solid phase extraction combined with inductively coupled plasma mass spectrometry was developed for the quantification of trace mercury, cadmium and lead in environmental water samples. The extraction conditions including sample pH, sample volume, sorbent amount, adsorption/desorption time and elution volume were optimized. Under the optimal conditions, three heavy metal ions were extracted from 150 mL aqueous solution in 10 min and eluted by 0.2 mol L−1 HNO3 containing 2% thiourea in 5 min. The method presented low limits of detection (0.21, 0.82 and 2.9 ng L−1) for target ions. The accuracy of the method was validated by using Certified Reference Materials of Environmental Water including GSB 07–1185–2000 (201435), GSB 07–1183–2000 (201239) and GSB 07–3173–2014 (202046). The application potential was further validated by the determination of trace mercury, cadmium and lead in Yangtze river and East lake water samples. The content of target heavy metal ions in tested water sample was found to be in the range of 6.40–195 ng L−1, and the recoveries of 86.4–109% were obtained at three spiking concentration levels for mercury, cadmium and lead ions.

Morphology-maintaining synthesis of copper hydroxy phosphate@metal–organic framework composite for extraction and determination of trace mercury in rice

A novel copper hydroxy phosphate@MOF composite DMP-Cu decorated by 2, 5-dimercapto-1, 3, 4-thiadiazol was facilely prepared and characterized. A dispersive SPE strategy using DMP-Cu as adsorbent combined with atomic fluorescence spectroscopy was developed for the selective capture of trace total mercury in rice sample. The adsorption mechanism showed that the Hg2+ removal process was fitted with pseudo second-order kinetics and the Langmuir adsorption model. The adsorbent was easy to be regenerated and the maximum adsorption capacity for the removal of Hg2+ was 249.5 mg g−1 at the optimal pH of 4. X-ray photoelectron spectroscopy and Raman spectra verified the selective and strong interaction between Hg2+ and thiol/nitrogen-containing functional groups of DMTZ on DMP-Cu. The trace total mercury in rice samples was determined with detection limit of 0.0125 ng mL−1 and relative standard deviation below 6%. The high recoveries were obtained in range of 98.8–109% for the spiked rice samples.

Reusable, facile, and rapid aptasensor capable of online determination of trace mercury

Herein, we reported a homemade waveguide-based evanescent wave aptasensor for the facile online monitoring of mercury pollution. The aptasensor exploited the high selectivity of hairpin structure-based thymidine–Hg2+–thymidine coordination chemistry (T–T mismatch) for Hg2+ recognition and the stably regenerable capability of DNA-functionalized waveguide surfaces. The presence of Hg2+ caused the T–T mismatch of Cy5.5-labeled T-rich single-stranded DNA sequences. The formed hairpin structures blocked the further hybridization of T-rich single-stranded DNA sequences with the complementary DNA strands that are modified on the waveguide surface; this phenomenon was accompanied by the decrease in the fluorescent signals excited by the evanescent wave. The limit of detection in real water samples was determined to be 0.2 μg/L, which was comparable with that of 0.4 μg/L in an ultrapure water under controlled conditions. And the linear range was observed from 1.4 µg/L to 240.7 µg/L. The negligible environmental matrix effect on the performance ensured the reliability of the proposed aptasensor. Moreover, the cross reactivity of this method toward other investigated metal ions was negligible. Through the delicate surface modification with DNA molecules covalently, the chip was reused at least 31 times with a relative standard deviation (RSD) of less than 19%. A Hg2+ pollution accident was successfully detected within 30 min, shedding new light in pollution monitoring, environment restoration, and emergency treatment.

Facile Trace Mercury (II) Sensor Using Statistically Optimized Electrochemical Co-deposited Gold Nanofilm Modified Screen-Printed Carbon Electrodes

Rapid detection of trace mercury (II) in water is very challenging. A novel sensor for the facile detection of mercury (II) was developed using electrochemically co-deposited gold nanofilm modified screen-printed carbon electrodes (EcoD-AuNF/SPCE). Because a monolayer of gold nanofilm is freshly co-deposited during the mercury (II) preconcentration period, no additional modification on an electrode is required prior to a test. Central composite design (CCD) and response surface methodology (RSM) were used to evaluate the effects of the critical testing parameters simultaneously (i.e., the co-deposited gold concentration of $350\,\,\mu \text{g}\,\,\text{L}^{-1}$ , deposition potential of −0.75 V, and testing pH of 3.50). The response of square-wave anodic stripping voltammetry (SWASV) showed a linear relationship with the mercury (II) concentration over a range of 1 to $40~\mu \text{g}$ /L (ppb), with an LoD of $0.29~\mu \text{g}$ /L and sensitivity of $0.37~\mu \text{A}$ /ppb. Significant influences on the mercury (II) stripping peak potential, peak height, and peak shape were observed in the presence of chloride. Therefore, an optimized amount of chloride (i.e., 600 mg/L) was preemptively added to minimize the potential effect of naturally occurring chloride and to improve further the detection sensitivity (i.e., LoD of $0.16~\mu \text{g}$ /L and sensitivity of $0.55~\mu \text{A}$ /ppb). Validation testing using real-world water samples indicated reliable prediction of mercury (II) concentration could be obtained in complex media. In summary, this newly developed voltammetric approach has excellent detection performance and practical significance for potential on-site voltammetric determination of trace mercury (II) in water.

Determination of Trace Mercury in Water by On-line Solid Phase Extraction and Ultraviolet Vapor Generation–ICP-MS

Determination of Trace Mercury in Water by On-line Solid Phase Extraction and Ultraviolet Vapor Generation–ICP-MS

Green preparation of CuI particles in dielectric barrier discharge for colorimetric determination of trace mercury in comparison with atomic fluorescence spectrometric determination

The present work describes a solution-free method for preparation of copper(I) iodide (CuI) particles on copper wire by dielectric barrier discharge (DBD). The prepared material was applied to develop a colorimetric semi-quantitative analysis for fast screening analysis of trace mercury (Hg) by combing mercury vapor generation with Hg/CuI chromogenic reaction. Under the optimized conditions, the proposed method was successfully explored for visual determination of trace Hg in natural water and certified reference samples, and the results were in good agreement with cold vapor generation-atomic fluorescence spectrometry (CVG-AFS). It was proved to be a green, fast, visual and portable method for the determination of trace Hg in these real samples. It is a potential field analytical method for fast screening analysis.

Insights into the anodic stripping voltammetric behaviour of copper film electrodes for determination of trace mercury

New insights into the attractive stripping voltammetric performance as well as scope and limitations of the in-situ formed copper film electrode (CuFE) for measuring low concentrations of mercury are presented. Several main operational parameters were investigated and optimised. These include the composition of measurement solution, the concentration of Cu(II), accumulation potential and time. The CuFE showed excellent sensitivity accompanied with well-defined and reproducible signals for Hg(II), and very low background contribution in the presence of dissolved oxygen. It displayed wide linear response in the examined concentration range of 5–120 μg L−1 along with a remarkably low limit of detection, i.e. 0.3 μg L−1 after 300 s accumulation, and excellent repeatability with RSDs of 1.8%. CuFE was tested for measuring trace mercury in real sea water sample using standard addition method with 98% recovery and was compared with a standard ICP-MS method. CuFE was compared with other most frequently used metal film electrodes and several solid carbon substrate materials were evaluated for its preparation. Measurements were also performed in the presence of various potential inorganic and organic interferences. The CuFE revealed very promising electroanalytical characteristics.

Electrochemical determination of trace mercury in water sample using EDTA-CPE modified electrode

The analytical performance of the EDTA-CPE sensor that is designed for the detection of metals was studied. EDTA plays an important role in the complexation of metal ions because of their good and high response to these ions. The modified electrode EDTA-CPE was used for the voltammetric determination of mercury ions (square wave voltammetry). Sodium chloride solution 0.3mol−1 was used as the support electrolyte. Using optimal parameters, calibration graph is linear (varying from 5 to 35∗10−4mol/l) for 5min of pre-concentration time with the detection limit of 16, 6×10−9molL−1. These results indicate that the developed method is simple, with high stability and sensitivity for the determination of low concentration of Hg (II).

Direct determination of trace mercury and cadmium in food by sequential electrothermal vaporization atomic fluorescence spectrometry using tungsten and gold coil traps

On the basis of vaporization temperature difference, a novel solid sampling AFS was developed for the sequential determination of trace Hg and Cd in food samples.

Reducing Vaporization - Catalytic Determination of Trace Mercury in Fresh-water Samples

Reducing Vaporization - Catalytic Determination of Trace Mercury in Fresh-water Samples

Tetrathiafulvalene aids in the atomic spectroscopic determination of total mercury

The determination of mercury simultaneously with other elements via inductively coupled plasma-mass spectrometry (ICP-MS) in airborne particulate matter (PM2.5) is still challenging due to the lack of accuracy for the low level mercury concentrations as a result of its volatility and tendency to adhere to the walls of the sample introduction system. This study investigated the effect of existing (gold and methionine) and new (lithium tetrathiafulvalene carboxylate (LiCTTF)) preservation agents in order to improve the determination of trace mercury in PM2.5 samples. Statistical analysis revealed that a concentration of 10 μg mL−1 of LiCTTF was sufficient to obtain highly accurate results with t values of 0.1044–1.1239 which are considerably less than the critical t value of 1.8 and apparent recoveries of 85–100%. An evaluation of the method revealed a spiked mercury recovery of 91% and a detection limit of 0.05 ng mL−1. The method was tested for the determination of trace metals in PM2.5 from atmospheric samples and led to the detection of low elemental concentrations in Singapore's atmosphere. The mechanism for the interaction of mercury with LiCTTF and tetrathiafulvalene (TTF) was studied by conducting in situ electrochemical studies. Cyclic voltammetry and square-wave voltammetry analyses of mercury, and mercury in presence of LiCTTF and TTF revealed complexation between the metal and sulfur-containing compounds.

A novel voltammetric sensor for mercury(II) based on mercaptocarboxylic acid intercalated layered double hydroxide nanoparticles modified electrode

A sensitive and selective electrochemical sensor based on thioglycolic acid intercalated Mg–Al LDH (Mg–Al–TGA LDH) modified electrode was described for the determination of trace mercury using square wave anodic stripping voltammetry (SWASV). The morphology and structure of the synthesized LDHs were characterized using transmission electron microscopy, Fourier transform IR and X–ray diffraction. Several variables affecting the stripping peak current such as the supporting electrolytes, pH value, deposition potential and deposition time, were carefully optimized. Under optimal conditions, the proposed sensor exhibited a wider linearity range from 2.0 to 800nM Hg(II) with a detection limit of 0.8nM (S/N=3), which was below the guideline values in drinking water given by the World Health Organization. The effect of some potentially interfering ions were also investigated and results indicated that the presence of major cations and anions has no obvious influence on the determination of Hg(II). This newly prepared sensor was successfully applied to determination of Hg(II) in water samples with good recovery, ranging from 97 to 104%.

An Electrochemical Method for the Determination of Trace Mercury (II) by Formation of Complexes With Indigo Carmine Food Dye and Its Analytical Application

An Electrochemical Method for the Determination of Trace Mercury (II) by Formation of Complexes With Indigo Carmine Food Dye and Its Analytical Application

Conductometric studies and application of new Schiff base ligand as carbon paste electrode modifier for mercury and cadmium determination

ABSTRACTA new chemically modified carbon paste electrode by 2,2ʹ-((pyridine-2,6-diylbis(azanylylidene))bis(methanylylidene))diphenol (L) ligand has been made and used as a sensor for determination of trace mercury and cadmium ions with cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods. Complexation studies of the ligand with Cu2+, Zn2+, Hg2+, Ni2+ and Cd2+ ions by conductometric method in acetonitrile–ethanol mixture at 25°C show that the ML complexes have formed. The formation constants of complexes were calculated from the computer fitting of the molar conductance–mole ratio data, and the stability of the resulting complexes varied in order of Cd2+ > Hg2+ > Cu2+ > Zn2+ > Ni2+. Then a simple and effective chemically modified carbon paste electrode with L was prepared, and the electrochemical properties and applications of the modified electrode were investigated. Under the optimal conditions, the detection limit was 0.0494 μg L−1 and 0.0782 μg L−1 for cadmium and mercury ions, respectively, and the linear range for both metal ions were from 1 to 100 μg L−1. The electrode shows high sensitivity, reproducibility and low cost, and was successfully applied to determination of Cd2+ and Hg2+ ions in water samples with recovery in the range of 97–101%.

Determination of trace mercury(ii) in wastewater using on-line flow injection spectrophotometry coupled with supported liquid membrane enrichment

An on-line flow-injection spectrophotometric method coupled with supported liquid membrane enrichment was developed to determine trace Hg(ii) in water.