Measurement Of Methylmercury Research Articles

Total, Methyl, and Ethyl Mercury in the U.S. Population, NHANES 2011-2012

Background: Whole blood measurement of methyl mercury (MeHg), a toxic form of Hg in seafood, has not been technically feasible. Total Hg (THg) has been used as a surrogate, or (MeHg) has been estim...

Luminescent bacteria-based sensing method for methylmercury specific determination

A bacterial biosensor method for the selective determination of a bioavailable organomercurial compound, methylmercury, is presented. A recombinant luminescent whole-cell bacterial strain responding to total mercury content in samples was used. The bacterial cells were freeze-dried and used as robust, reagent-like compounds, without batch-to-batch variations. In this bacteria-based sensing method, luciferase is used as a reporter, which requires no substrate additions, therefore allowing homogenous, real-time monitoring of the reporter gene expression. A noninducible, constitutively light-producing control bacterial strain was included in parallel for determining the overall cytotoxicity of the samples. The specificity of the total mercury sensor Escherichia coli MC1061 (pmerRBlux) bacterial resistance system toward methylmercury is due to a coexpressed specific enzyme, organomercurial lyase. This enzyme mediates the cleavage of the carbon-mercury bond of methylmercury to yield mercury ions, which induce the reporter genes and produce a self-luminescent cell. The selective analysis of methylmercury with the total mercury strain is achieved by specifically chelating the inorganic mercury species from the sample using an optimized concentration of EDTA as a chelating agent. After the treatment with the chelating agent, a cross-reactivity of 0.2% with ionic mercury was observed at nonphysiological ionic mercury concentrations (100nM). The assay was optimized to be performed in 3h but results can already be read after 1h incubation. Total mercury strain E. coli MC1061 (pmerRBlux) has been shown to be highly sensitive and capable of determining methylmercury at a subnanomolar level in optimized assay conditions with a very high dynamic range of two decades. The limit of detection of 75ng/l (300 pM) allows measurement of methylmercury even from natural samples.

Measurement of methyl mercury (I) and mercury (II) in fish tissues and sediments by HPLC-ICPMS and HPLC-HGAAS

A procedure for the extraction and determination of methyl mercury and mercury (II) in fish muscle tissues and sediment samples is presented. The procedure involves extraction with 5% (v/v) 2-mercaptoethanol, separation and determination of mercury species by HPLC-ICPMS using a Perkin-Elmer 3μm C8 (33mm×3mm) column and a mobile phase 3 containing 0.5% (v/v) 2-mercaptoethanol and 5% (v/v) CH3OH (pH 5.5) at a flow rate 1.5mlmin−1 and a temperature of 25°C. Calibration curves for methyl mercury (I) and mercury (II) standards were linear in the range of 0–100μgl−1 (r2=0.9990 and r2=0.9995 respectively). The lowest measurable mercury was 0.4μgl−1 which corresponds to 0.01μgg−1 in fish tissues and sediments. Methyl mercury concentrations measured in biological certified reference materials, NRCC DORM – 2 Dogfish muscle (4.4±0.8μgg−1), NRCC Dolt – 3 Dogfish liver (1.55±0.09μgg−1), NIST RM 50 Albacore Tuna (0.89±0.08μgg−1) and IRMM IMEP-20 Tuna fish (3.6±0.6μgg−1) were in agreement with the certified value (4.47±0.32μgg−1, 1.59±0.12μgg−1, 0.87±0.03μgg−1, 4.24±0.27μgg−1 respectively). For the sediment reference material ERM CC 580, a methyl mercury concentration of 0.070±0.002μgg−1 was measured which corresponds to an extraction efficiency of 92±3% of certified values (0.076±0.04μgg−1) but within the range of published values (0.040–0.084μgg−1; mean±s.d.: 0.073±0.05μgg−1, n=40) for this material. The extraction procedure for the fish tissues was also compared against an enzymatic extraction using Protease type XIV that has been previously published and similar results were obtained. The use of HPLC-HGAAS with a Phenomenox 5μm Luna C18 (250mm×4.6mm) column and a mobile phase containing 0.06moll−1 ammonium acetate (Merck Pty Limited, Australia) in 5% (v/v) methanol and 0.1% (w/v) l-cysteine at 25°C was evaluated as a complementary alternative to HPLC-ICPMS for the measurement of mercury species in fish tissues. The lowest measurable mercury concentration was 2μgl−1 and this corresponds to 0.1μgg−1 in fish tissues. Analysis of enzymatic extracts analysed by HPLC-HGAAS and HPLC-ICPMS gave equivalent results.

Measurements of methylmercury, ethylmercury, and inorganic mercury species in a whole blood standard reference material: SRM 955c—Toxic Elements in Caprine Blood

Trace elemental speciation analysis is assuming more critical importance in nutritional and toxicological assessments, and despite the necessity to quantitatively differentiate elemental species in environmental and clinical samples, there are a limited number of reference materials suitable for this purpose. A whole blood certified reference material, SRM 955c Toxic Elements in Caprine Blood was developed for the determination of toxic metals in whole blood including mercury. The certification of methylmercury, ethylmercury, and inorganic mercury was carried out by triple spike speciated isotope dilution inductively coupled plasma mass spectrometry (TS-SID-GC/ICP-MS) and represents the first whole blood material certified for three mercury species. The certified values (±expanded uncertainty) of methylmercury, ethylmercury, inorganic mercury and total mercury in SRM 955c are 4.5 ± 1.0 µg L−1, 5.1 ± 0.5 µg L−1, 9.0 ± 1.3 µg L−1, and 17.8 ± 1.6 µg L−1 respectively.

Construction and Evaluation of a Low Cost Interface for the Determination of Elemental Speciation by Gas Chromatography Coupled to Inductively Coupled Plasma Mass Spectrometry (GC‐ICP‐MS)

The construction and evaluation of a low cost, easily demountable interface to couple capillary gas chromatography to inductively coupled plasma mass spectrometry detection is described. Using this interface, the capillary column can be maintained at a high temperature through to the tip of the torch injector using a transfer line heated by a combination of hot argon and electrical resistance. The interface is suitable for analytes with boiling points up to 230°C, allowing for the analysis of low and high boiling analytes in a single injection. The system was evaluated by the determination of the butyltin species in a marine sediment CRM using conventional calibration with tripropyltin dichloride as the internal standard and the measurement of methylmercury in a tuna fish CRM via species‐specific isotope dilution analysis. Detailed information on the design and construction of the interface are included to facilitate its construction and use by other workers.

Measurement of methylmercury and mercury in run-off, lake and rain waters

During one year, samples from eight drainage lakes, seven run-off stations and three deposition sites from various geographical areas in Sweden were collected and analyzed for methyl Hg (MeHg) and total Hg (Hg-tot). The MeHg concentrations ranged from 0.04 to 0.64 ng L−1, 0.04 to 0.8 ng L−1, and <0.05 to 0.6 ng L−1 in run-off, lake water and rain water, respectively. The corresponding Hg-tot concentrations were found in the range 2 to 12 ng L−1, 1.35 to 15 ng L−1, and 7 to 90 ng L−1, respectively. A Hg-tot level of about 60 ng Hg L−1 was found in throughfall water. The MeHg and Hg-tot concentrations are positively correlated in both run-off and lake water, but not in rain and throughfall water. A strong positive correlation between the MeHg, as well as the Hg-tot concentration, and the water color is observed in both run-off and lake waters, which suggests that the transport of MeHg and other Hg fractions from soil via run-off water to the lake is closely related to the transport of organic substances; and is a consequence of the biogeochemical processes and the water flow pathway. The ratio between the mean values of MeHg and Hg-tot seems to be an important parameter, with an indicated negative coupling to the mean value of pH for run-off water, but a strong positive correlation to Hg-content in fish, the ratio between the area of the catchment and the lake, as well as to the retention time of lake.

Adsorption and Desorption of Mercury Compounds on Head Hair in Aqueous Solutions

Adsorption of HgCl2 and CH3HgCl in aqueous solutions by the hair was measured at 20°C and 30 °C. The concentration of adsorbed Hg was higher at 30°C than 20°C; both isotherms adapted well to Freundrich equation.An increased mercury concentration on the hair was clear even in extremely dilute mercury solutions.Desorption of HgCl2 adsorbed by the hair was poor when hair was washed with HCl solutions. But the CH3HgCl on the hair was eluted very well with 1N HCl solution. A washing with 1mM of L-cysteine did not elute the mercury on the hair much.Thus, desorption of only the outer-adsorbed mercury on head hair is considered impossible. Measurement of methylmercury is recomended as a sign of internal organic mercury absorption.