Direct Determination Of Mercury Research Articles

Novel Platinum-Nickel Composite Trap for Simultaneous and Direct Determination of Mercury and Cadmium in Soil and Its Mechanism Study.

In this work, following a metal-ceramic heater (MCH) as an electrothermal vaporizer (ETV), a novel composite Pt/Ni trap based on platinizing the foamed nickel was first fabricated to trap Hg and Cd simultaneously. So, a solid sampling Hg-Cd analyzer was developed to simultaneously detect trace Hg and Cd in soil samples, mainly consisting of an MCH, a composite Pt/Ni trap, and an atomic fluorescence spectrometer (AFS). This small-size MCH-ETV system only consumes 100 W for the complete vaporization of Hg and Cd in soil matrices. The Pt/Ni trap fulfills the complete trapping of Hg and Cd following the solid sampling MCH-ETV system and then fast releases them by heating. It was proved that trapped and released Hg and Cd by the Pt/Ni trap are atomic species using X-ray photoelectron spectroscopy (XPS) and other approaches; specially, the effective cotrapping of Hg and Cd might be due to forming alloys of Hg + Pt and Cd + Ni on the Pt/Ni trap. Under the optimized conditions, the method detection limits (LODs) of Hg and Cd reached 0.4 μg/kg and 0.04 μg/kg for a 20 mg sample size, the relative standard deviations (RSDs) were within 12% and 8% for soil samples, respectively, and the recoveries ranged from 96% to 105%, indicating favorable analytical sensitivity, precision, and accuracy. The whole analysis time can be controlled within 5 min without the soil digestion process. The proposed Hg-Cd analyzer is thus suitable for rapid detection of Hg and Cd in soil samples with advantages such as simplicity, green, and safety. Further, the proposed solid sampling ETV-composite trap method has a promising application potential in the field and rapid detection for multielements.

A Liquid Membrane Mercury Selective Electrode Based on 2-(N-pipyridino Methyl)-1-Cyano Cyclohexanol as a Novel Neutral Carrier

2-(N-pipyridino methyl)-1-cyano cyclohexanol was synthesized, characterized and used as an ionophore in construction of polyvinyl chloride (PVC) potentiometric sensor for Hg2+ determination. The best result was obtained with membrane composition of PVC (29%), sodium tetraphenylborate as ionic additive (1%), 2-(N-pipyridino methyl)-1-cyano cyclohexanol (12%) and dibutylphthalate (58%). The designed electrode showed an acceptable Nernstian slope (29.1 mV/decade) for Hg2+ over a wide concentration range from 5 × 10–7 to 1 × 10–2 M with a detection limit of 2.5 × 10–7 M. The potential response was independent from pH in the range of 6.0–9.0 and the sensor response time was relatively short (~25 s). The sensor performance was invariable for at least 6 weeks. Electrode selectivity was evaluated by matched potential method. Finally, the proposed sensor was used as an indicator electrode in potentiometric titration of Hg2+ with ethylenediaminetetraacetic acid and in direct determination of mercury(II) in aqueous samples with admissible accuracy and high reproducibility.

DIRECT DETERMINATION OF THE CONTENT OF MERCURY AND LEAD IN THE BLOOD OF PREGNANT WOMEN AND THE INFLUENCE OF THEIR LEVEL ON THE TERMINATION OF PREGNANCY IN EARLY TERMS

A methodological approach for the direct determination of mercury in the blood using analyzer RA-915 with pyrolytic decomposition of the sample has been developed. The detection limit of the proposed technique is 0,5 µg/L with the relative standard deviation not exceeding 10%. To determine the lead content, the previously created method of direct lead determination in the blood has been used. In the second stage of the study, biomonitoring of pregnant women has been carried out in order to identify the relationship between the termination of pregnancy in early terms with the content of mercury and lead in women’s blood. The study involved 25 women with a diagnosis of non-developing pregnancy, and 47 women from the control group. As a result of the conducted studies, it has been found that the contents of mercury and lead in women with nondeveloping pregnancy were almost 25% higher.

Application of TDA AAS to Direct Mercury Determination in Postmortem Material in Forensic Toxicology Examinations.

Mercury is a heavy metal with high toxicity, the level of which depends on the form of the metal. One of the newer techniques for determining trace amounts of total mercury in various materials, including biological samples, is thermal decomposition, amalgamation and atomic absorption spectrometry (TDA AAS). The TDA AAS method was optimized and validated using a mercury analyzer (DMA-80). The limits of detection for mercury were 0.10 and 0.20 μg/L (nickel and quartz boats, respectively). The working range of the calibration curve was at least from 0.6 to 200 ng Hg/mL; the intra-day precision in samples (RSD)-in the range of: 1.66-6.86% (blood), 0.82-1.47% (urine) and 2.01-3.44% (hair); the inter-day precision (over 8 days): 2.51%, and 2.5% (blood spiked with 2.5 and 10 ng Hg, respectively), 5.10% and 3.16% (urine spiked with 2.0 and 6.0 ng Hg, respectively). The accuracy (as relative error, mean value) determined on the basis of the study of reference materials of blood (Seronorm Trace Elements Whole Blood L-1, L-2, L-3), urine (Seronorm Trace Elements Urine, Urine L-2), and hair (Human Hair NIES CRM No. 13) was: 2.00% (blood), 0.50% (urine) and 0.86% (hair); recovery of 2.5 ng Hg (blood): 93-97%. The method was used for the determination of mercury in 76 samples of various biological matrices, including samples of whole blood, urine, hair, bile and vitreous humor. Mercury concentrations in postmortem blood (n = 24) were in the range: 0.61-12.4 μg/L (median 3.02 μg/L); urine (n = 12): 0.16-2.19 μg/L (median 0.81 μg/L); hair (n = 14): 0.08-0.53 μg/g (median 0.22 μg/g); bile (n = 12): 1.15-7.11 μg/L (median 2.41 μg/L and vitreous humor (n = 13): 0.22-1.01 μg/L (median 0.47 μg/L). The method is suitable for the purposes of forensic toxicology analysis.

Development of an electrothermal vaporizer for direct mercury determination in soil by inductively-coupled plasma mass spectrometry

The need to determine mercury in environmental samples is well known, along with its related difficulty. Most methods require samples to be decomposed, involving the use of concentrated acids; this requires considerable time and is liable to lead to analyte loss. The aim of this work is to develop a simple electrothermal vaporization (ETV) system coupled to inductively coupled plasma mass spectrometry (ICP-MS) for Hg determination by direct solid sample analysis (DSSA). The ETV system consists of a high-power lamp enclosed in glass chamber equipped with solenoid valves to control the flow of argon gas (Ar) during pyrolysis and vaporization steps. The system is controlled by a printed circuit board and software developed in the LabVIEW environment. In this system, the analyte vapour was extracted through a glass tube positioned just above the sample, avoiding the analyte deposition on the chamber wall and consequently reducing memory effect. The heating program was optimised and the pyrolysis step was not necessary since it was possible to vaporize the analyte at relatively low temperature (700 °C) without matrix interference. Soil mass between 0.500 and 5.000 mg can be analysed with the ETV system. Calibration was carried out by using a certified reference material (CRM) of soil (NIST2709) ranged from 0.1 to 1.0 ng of Hg. The relative standard deviation was lower than 20% (n = 3) and the limit of quantification (10σ) of Hg was 3.1 ng g−1. The accuracy was evaluated by comparison of results obtained for Hg in CRMs and no statistical differences were observed (paired t-test at a confidence level of 95%). To evaluate the performance of ETV system, soil samples with different concentration levels were analysed and the results were in good agreement (paired t-test at a confidence level of 95%) with those obtained by nebulization-ICP-MS (NEB-ICP-MS) after acid extraction. Therefore, the proposed method can be used for routine analysis, where the time of analysis of approximately 60 s per sample, risk of contamination, analyte losses and generation of residues are drastically reduced in comparison with techniques that require sample extraction for Hg determination by NEB-ICP-MS.

Direct mercury determination in blood and urine by means of high-resolution continuum source graphite furnace atomic absorption spectrometry using gold nanoparticles as a chemical modifier

The use of Au nanoparticles as a chemical modifier permits the direct Hg determination in urine and blood samples by HR CS GFAAS.

Fast and accurate methodology for direct mercury determination in hair and nails

AbstractA solvent-free, easy, fast and waste-free methodology was developed for the determination of total mercury levels in hair and nails. Samples were taken from several volunteers and directly analysed, with levels of mercury in the range between 0.5 and 8 ng/mg. The influence of quantity of hair, as well as the addition of small amount of solvent and the necessity of previous treatment were studied. Also, a history of mercury exposure was provided by the distance of the hair from the scalp of each volunteer, the results of which were correlated with fish consumption. Furthermore, a short study of mercury in nails was carried out and correlated to the results from hair mercury levels. A small quantity of 5 mg of hair with an addition of 50 μL of water to the sample without previous treatment was adequate to get a representative result in less than 10 minutes. The accuracy of the proposed method was confirmed by analysing certified reference materials including Coal Fly Ash-NIST SRM 1633b, Fucus-IAEA 140 and three unpolished Rice Flour NIES-10. The observed results were found to be in good agreement with the certified values.

Design and evaluation of sensory systems based on amphiphilic anthraquinones molecular receptors

A new paradigm is described that allows one to create different types of sensors: from highly sensitive ones to practical household devices. Our approach relies on modular molecular receptors incorporating an intensely-colored aminoanthraquinone signaling unit equipped with both hydrophilic and hydrophobic modules, the number and size of which being configured in accordance with the targeted analyte and the sought detection method. An important advantage is the compliance with some principles of green chemistry, avoiding the use of toxic organic solvents. The proper functionalization of the anthraquinone scaffold afforded water-soluble chromoinophores capable of quantifying selectively Hg2+ and/or Cu2+ in aqueous solutions down to the ppm level. The versatility of these ligands was exemplified by exploiting the self-assembling processes at the water–air interface of amphiphilic derivatives in order to produce metal-ion responsive films. The copper(II) and mercury(II) sensing properties of Langmuir monolayers floating on the water surface or transferred onto a quartz slice by the Langmuir–Blodgett technology have been investigated and are discussed. By adjusting the hydrophilic-lipophilic balance, ready-to-use dip tests could also be elaborated either by incorporating the colorimetric indicators in thick polymer films or by impregnating paper strips following a sol–gel process. These sensors possess the necessary sensitivity and selectivity for the direct determination of mercury and copper levels, as required for industrial-processes, waste disposal, environmental monitoring, clinical toxicology, or even for household applications.

Determination of Total Mercury in Fish Tissue Using a Low-Cost Cold Vapor Capacitively Coupled Plasma Microtorch Optical Emission Microspectrometer: Comparison with Direct Mercury Determination by Thermal Decomposition Atomic Absorption Spectrometry

A method for total Hg determination in fish tissue using cold vapor capacitively coupled plasma microtorch optical emission spectrometry was evaluated. The low-cost miniaturized analytical system includes a low power plasma microtorch (10 W) and low Ar consumption (150 ml min−1) and a QE65Pro microspectrometer as detector. Lyophilized fish tissues were microwave-assisted digested in HNO3–H2O2 mixture, brought in 5 % (v/v) HCl, then Hg vapor was chemically generated with 20 % SnCl2 solution stabilized in 15 % (v/v) HCl. The figures of merit of the proposed method were evaluated by analyzing certified reference materials and test samples and compared to those of the well-established thermal decomposition atomic absorption spectrometry method. The analytical characteristics (limits of detection and quantification, precision, and accuracy) comply with requirements for Hg determination in seafood set out in Decisions 2007/333/EC and 2002/657/EC. The limits of detection and quantification of the proposed method were 3 and 9 μg kg−1 Hg in dry mass, similar to those in thermal decomposition atomic absorption spectrometry. The precision was between 1.8 and 5.5 % for concentrations in the range 0.18–0.76 mg kg−1 Hg, while the accuracy was 99.7 ± 3.0 %. The significance tests revealed no difference between the results obtained by the two methods. The proposed miniaturized spectrometric equipment could be the subject of prototyping as low-cost instrumentation for designed applications in seafood control.

Matrix-Assisted Photochemical Vapor Generation for the Direct Determination of Mercury in Domestic Wastewater by Atomic Fluorescence Spectrometry

ABSTRACT In this article, matrix-assisted photochemical vapor generation is proposed for the direct determination of mercury in domestic wastewater by atomic fluorescence spectrometry. With the ultraviolet light irradiation, the matrix (low-molecular-weight organic compounds) in domestic wastewater samples can produce reducing species. These reducing species could reduce mercury from mercury (II) to elemental mercury, subsequently swept by argon to atomic fluorescence spectrometry for detection. The effects of several factors, such as material of the photoreaction coil, ultraviolet light wavelength, ultraviolet light irradiation time, and flow rate of carrier gas, were investigated. Under the optimized condition, a limit of detection of 0.1 µg L−1 was obtained. The standard addition method was used for the spiked mercury domestic wastewater sample analysis, with a relative standard deviation (n = 11, at 20 µg L−1) of 4.8%, and recovery test results ranged from 81% to 110%. The proposed method was applied to analyze two certified reference materials and four domestic wastewater samples, with analytical results in good agreement with certified values or those obtained by ICP-MS. Interferences from common transition metals and alkaline metals as well as alkaline earth metals were also investigated. This is a simple, reagent-free, cost-effective, green method for mercury determination in domestic wastewater.

Direct determination of mercury in cosmetic samples by isotope dilution inductively coupled plasma mass spectrometry after dissolution with formic acid

A new method was proposed for the accurate determination of mercury in cosmetic samples based on isotopic dilution (ID)-photochemical vapor generation (PVG)-inductively coupled plasma mass spectrometry (ICP MS) measurement. Cosmetic samples were directly dissolved in formic acid solution and subsequently subjected to PVG for the reduction of mercury into vapor species following by ICP MS detection. Therefore, the risks of analyte contamination and loss were avoided. Highly enriched 201Hg isotopic spike is added to cosmetics and the isotope ratios of 201Hg/202Hg were measured for the quantitation of mercury. With ID calibration, the influences originating from sample matrixes for the determination of mercury in cosmetic samples have been efficiently eliminated. The effects of several experimental parameters, such as the concentration of the formic acid, and the flow rates of carrier gas and sample were investigated. The method provided good reproducibility and the detection limits were found to be 0.6pgmL−1. Finally, the developed method was successfully applied for the determination of mercury in six cosmetic samples and a spike test was performed to verify the accuracy of the method.

Direct Determination of Mercury in Solid Samples by Low Temperate Plasma Coupled with Atomic Fluorescence Spectrometry

Direct Determination of Mercury in Solid Samples by Low Temperate Plasma Coupled with Atomic Fluorescence Spectrometry

Direct Determination of Inorganic Mercury in Ethanol Fuel by Cold Vapor Atomic Absorption Spectrometry

A simple method for the direct determination of mercury in ethanol fuel samples diluted with water by cold vapor atomic absorption spectrometry (CV-AAS) is proposed. The chemical parameters (concentrations of NaBH4 and HCl) used for the Hg vapor generation for its measurement by CV-AAS were optimized. The calibration curve showed a linear response over the studied range (1–25 μg L–1), with a correlation coefficient of 0.9999 and limits of detection and quantification of 0.05 and 0.17 μg L–1, respectively. The relative standard deviations were lower than 3.5%. The accuracy of the method was estimated by applying the recovery test, and recovery values obtained were 84 and 106%. A sample throughput of 45 h–1 was achieved. Simplicity and sensitivity are among the advantages offered by the proposed method.

Formation of Nanocolloidal Metacinnabar in Mercury-DOM-Sulfide Systems

Direct determination of mercury (Hg) speciation in sulfide-containing environments is confounded by low mercury concentrations and poor analytical sensitivity. Here we report the results of experiments designed to assess mercury speciation at environmentally relevant ratios of mercury to dissolved organic matter (DOM) (i.e., <4 nmol Hg (mg DOM)(-1)) by combining solid phase extraction using C(18) resin with extended X-ray absorption fine structure (EXAFS) spectroscopy. Aqueous Hg(II) and a DOM isolate were equilibrated in the presence and absence of 100 μM total sulfide. In the absence of sulfide, mercury adsorption to the resin increased as the Hg:DOM ratio decreased and as the strength of Hg-DOM binding increased. EXAFS analysis indicated that in the absence of sulfide, mercury bonds with an average of 2.4 ± 0.2 sulfur atoms with a bond length typical of mercury-organic thiol ligands (2.35 Å). In the presence of sulfide, mercury showed greater affinity for the C(18) resin, and its chromatographic behavior was independent of Hg:DOM ratio. EXAFS analysis showed mercury-sulfur bonds with a longer interatomic distance (2.51-2.53 Å) similar to the mercury-sulfur bond distance in metacinnabar (2.53 Å) regardless of the Hg:DOM ratio. For all samples containing sulfide, the sulfur coordination number was below the ideal four-coordinate structure of metacinnabar. At a low Hg:DOM ratio where strong binding DOM sites may control mercury speciation (1.9 nmol mg(-1)) mercury was coordinated by 2.3 ± 0.2 sulfur atoms, and the coordination number rose with increasing Hg:DOM ratio. The less-than-ideal coordination numbers indicate metacinnabar-like species on the nanometer scale, and the positive correlation between Hg:DOM ratio and sulfur coordination number suggests progressively increasing particle size or crystalline order with increasing abundance of mercury with respect to DOM. In DOM-containing sulfidic systems nanocolloidal metacinnabar-like species may form, and these species need to be considered when addressing mercury biogeochemistry.

Ultra trace mercury(II) detection by a highly selective new optical sensor

This paper presents the development and construction of a sensitive new optical sensor that is highly selective to Hg 2+ ion in aqueous solution. The sensing element, the newly synthesized (1Z,2Z)-N′ 1,N′ 2-dihydroxy-N 1,N 2-dipyridin-2-ylethanediimidamide, incorporated into a plasticized poly(vinyl chloride) membrane, is capable of determining mercury(II) with a high selectivity over a wide dynamic range from 5.78 × 10 −9 to 1.05 × 10 −3 M at pH 4.0 with a lower detection limit of 1.71 × 10 −9 M. The optode membrane's response to Hg 2+ is fully reversible and reveals a very good selectivity towards Hg 2+ ion over a wide variety of other metal ions in solution. Performance characteristics of the sensor evaluated as good reversibility, wide dynamic range, long life span, long-term response stability, and high reproducibility. The proposed optical sensor gives good results for applications in direct determination of mercury(II) in environmental real samples that are satisfactorily comparable with corresponding data from cold-vapor atomic absorption spectrometry.

Evaluation of Direct Determination of Mercury in Whole Human Blood Using a Mercury Analyzer

Evaluation of Direct Determination of Mercury in Whole Human Blood Using a Mercury Analyzer

Imaging Time-Resolved Electrothermal Atomization Laser-Excited Atomic Fluorescence Spectrometry for Determination of Mercury in Seawater

In this study, direct determination of mercury at the nanogram per liter level in the complex seawater matrix by imaging time-resolved electrothermal atomization laser-excited atomic fluorescence spectrometry (ITR-ETA-LEAFS) is described. In the case of mercury, the use of a nonresonant line for fluorescence detection with only one laser excitation is not possible. For measurements at the 253.652 nm resonant line, scattering phenomena have been minimized by eliminating the simultaneous vaporization of salts and by using temporal resolution and the imaging mode of the camera. Electrothermal conditions (0.1 M oxalic acid as matrix modifier, low atomization temperature) have been optimized in order to suppress chemical interferences and to obtain a good separation of specific signal and seawater background signal. For ETA-LEAFS, a specific response has been obtained for Hg with the use of time resolution. Moreover, an important improvement of the detection limit has been obtained by selecting, from the furnace image, pixels collecting the lowest number of scattered photons. Using optimal experimental conditions, a detection limit of 10 ng L(-1) for 10 μL of sample, close to the lowest concentration level of total Hg in the open ocean, has been obtained.

A novel lariat crown compound as ionophore for construction of a mercury(II)-selective electrode

The construction, performance, and application of a new PVC membrane electrode for determination of the mercury(II) ion, based on 8,17-bis(pyren-1-ylmethyl)-6,7,8,9,15,16,17,18-octahydrodibenzo[f,m][1,8,4,11]dithiadiazacyclotetradecine as an ionophore, is described. The effects of factors such as membrane composition, the nature and amount of the plasticizers and additives, and pH for the improved sensitivity of the electrode were studied. The electrode had a Nernstian response for mercury(II) ions over the concentration range 1.0 × 10−2–1.0 × 10−6 mol dm−3 with a slope of 27.6 ± 0.6 mV/pHg. The detection limit for mercury(II) was 7.9 × 10−7 mol dm−3. The response time of the electrode was between 5 and 15 s, depending on the concentration of mercury, and it can be used in a pH range 4.0–4.5 for approximately 4 months without any substantial divergence of the response characteristics. It showed higher selectivity for mercury(II) ions than for several common alkali, alkaline earth, and transition metal ions except silver(I). The proposed electrode was successfully applied to direct determination of mercury in a dental filling amalgam alloy as a real sample with a complex matrix and as an indicator electrode in complexation titrations. .

Direct determination of mercury in white vinegar by matrix assisted photochemical vapor generation atomic fluorescence spectrometry detection

This paper proposes the use of photochemical vapor generation with acetic acid as sample introduction for the direct determination of ultra-trace mercury in white vinegars by atomic fluorescence spectrometry. Under ultraviolet irradiation, the sample matrix (acetic acid) can reduce mercury ion to atomic mercury Hg 0, which is swept by argon gas into an atomic fluorescence spectrometer for subsequent analytical measurements. The effects of several factors such as the concentration of acetic acid, irradiation time, the flow rate of the carrier gas and matrix effects were discussed and optimized to give detection limits of 0.08 ng mL − 1 for mercury. Using the experimental conditions established during the optimization (3% v/v acetic acid, 30 s irradiation time and 20 W mercury lamp), the precision levels, expressed as relative standard deviation, were 4.6% (one day) and 7.8% (inter-day) for mercury ( n = 9). Addition/recovery tests for evaluation of the accuracy were in the range of 92–98% for mercury. The method was also validated by analysis of vinegar samples without detectable amount of Hg spiked with aqueous standard reference materials (GBW(E) 080392 and GBW(E) 080393). The results were also compared with those obtained by acid digestion procedure and determination of mercury by ICP-MS. There was no significant difference between the results obtained by the two methods based on a t-test (at 95% confidence level).

Sol–gel derived highly selective optical sensor for sensitive determination of the mercury(II) ion in solution

We report a versatile optical sensor by incorporating the indicator dye 4-phenyl-2,6-bis(2,3,5,6-tetrahydrobenzo[b][1,4,7]trioxononin-9-yl)pyrylium perchlorate into a sol–gel layer. The proposed optical sensor that is stable, fast and highly selective to Hg 2+ ions shows a significant absorbance signal change on exposure to an aqueous solution containing mercury(II) ion. The sensing film is able to determine mercury(II) ion in aqueous solution with a high selectivity over a wide dynamic range between 1.52 × 10 −9 and 1.70 × 10 −2 M, at pH 5, and a lower detection limit of 1.11 × 10 −9 M. Validation of the assay method revealed excellent performance characteristics for Hg 2+ ions over a wide variety of other metal ions, including good selectivity, long-term response stability and high reproducibility. Applications, for the direct determination of mercury(II) in real samples, gave the results with good correlation with the data obtained by using cold vapor atomic absorption spectrometry.