Quantitative Spurenbestimmung von Quecksilber im Harn nach elektrolytischer Anreicherung

A flameless atomicabsorption method (Brandenberger and Bader [1]) was taken up to determine the amounts of mercury in urine. The procedure was extended to special problems of occupational medicine. The mercury is collected on a copper wire by electrolysis. The wire is heated electrically in the light path of an atomic absorption spectrophotometer, the evaporating mercury diminishing the beam of a hollow cathode lamp. The change of intensity is recorded in an analogous way. After 60 min of electrolysis (15 mA, 3 V) 97.4% of mercury have been recovered. The relative detection limit, referred to 1% absorption, is 1 µg of mercury/l. An accuracy of 10% is obtained when measuring in urine. An average of 4.31 ± 2.33 µg of mercury was found when the urines of 26 non-exposed men were analyzed.     

晋城煤中汞的热稳定性与赋存形态的研究

利用程序升温热解反应器─元素汞在线检测系统联用装置,研究了晋城煤中汞的热稳定性以及与热稳定性相关的晋城煤中汞的赋存形态。研究表明,煤中大部分汞与煤中无机矿物质伴/共生,少部分与煤中有机质伴/共生。其中,在200℃~300℃和900℃~1200℃释放的汞与煤中无机矿物质伴/共生,在300℃~600℃释放的汞部分与无机矿物质伴/共生,部分与煤中有机质伴/共生。     

用间接法测定硫化物的研究

前人已经报道用汞的冷原子吸收法测定硫化物,利用Hg~(2+)和S~(2-)形成很稳定的化合物,使汞的吸光度值降低,根据其降低的程度来测定硫化物的含量。这种方法简便、灵敏,但对加入的Hg~(2+)量有较大的限制。S_2O_3~(2-)、CN~-、I~-等也有严重干扰,这些离子常与S~(2-)共存于水样中,所以,实际测定时,常需分离这些离子。     

Possible interferences of mercury sulfur compounds with ethylated and methylated mercury species using HPLC-ICP-MS

The HPLC-ICP-MS coupling technique is able to separate and detect methyl, ethyl and inorganic mercury isotopes specifically. An identification of ethyl mercury(+) is not possible when the widely used sodium tetraethylborate derivatisation method in combination with GC-AFS/AAS or ICP-MS techniques is performed because it contains ethyl groups.An unidentified compound with the same retention time as ethyl mercury was found in the HPLC chromatograms of industrial sewage samples and humic-rich soils of microcosm experiments after applying water vapour distillation. We also observed such unidentified peaks in samples of heavily contaminated sites in Eastern Germany, separated by HPLC fractionation only. In the experiments described, different mercury sulfur adducts were synthesised and tested for their retention times in the HPLC-ICP-MS system. It was found that the compound CH₃–S–Hg⁺ showed the same retention time as the ethyl mercury standard. It is therefore possible that ethyl mercury detected in chromatography by comparison of the retention time could also be due to an adduct of a sulfur compound and a mercury species. CH₃–S–Hg⁺ should be tested in other chromatographic mercury speciation methods for this effect.This work can also be regarded as a contribution to the discussion of artificially occurring methyl mercury in sediments during sample preparation.     

荧光光度法测定大气、水和土壤中痕量汞

本文研究了汞离子与硫化荧光素汞反应定量地释放出荧光素汞的条件,提出了一种间接测定痕量汞的荧光光度法。应用于大气、水和土壤中痕量汞的测定,方法简便、快速。     

Anodic stripping determination of Pt(IV) based on the anodic oxidation of Hg and Cd from electrochemically deposited Hg–Pt and Hg–Cd alloy phases

An anodic stripping voltammetric determination of Pt(IV) is described which is based on depositing intermetallic mercury–platinum and cadmium–platinum alloy phase on the surface graphite electrode, and recording the oxidation peak of mercury and cadmium from these phases with the help of linear scan voltammetry. Three alloy phases are formed in the case of mercury–platinum, whereas only one phase appears in the case of cadmium–platinum.     

Visible near-infrared chemosensor for mercury ion

A visible near-infrared chemosensor (MCy-1) for mercury ions was successfully devised and characterized. A large red-shift (122 nm) of the absorption maximum of MCy-1 was observed. An important feature for the new chemosensor is its high selectivity towards mercury ions over the other competitive species, making the "naked-eye" detection of mercury ions possible.     

Improved instrument for mercury determination by atomic fluorescence spectrometry with a high-frequency electrodeless discharge lamp

An instrument for the determination of mercury at nanogram levels is described. With aeration, collection on gold wool and a mercury radiofrequency electrodeless discharge lamp, high sensitivity is obtained with a detection limit of 0.01 ng. The system is used for analysis of sea water.     

MD studies of electrolyte solution|liquid mercury interfaces

We report molecular dynamics (MD) computer simulations of a single lithium or iodide ion near a water|liquid mercury interface. The ion–mercury and the water–mercury potentials are derived from ab initio calculations of an ion or a water molecule and a mercury cluster consisting of seven, nine or 10 atoms. The flexible BJH water model and a mercury–mercury potential derived from pseudopotential theory are employed. The ion–water potentials are also based on ab initio calculations. The structural properties at the interfaces are described in terms of various density profiles and the ion–mercury radial distribution functions (RDF). An analysis of the induced rearrangements of the mercury atoms at and below the surface is also performed. Finally, the spectral densities of the hindered translational motions of the ions parallel and perpendicular to the mercury surface are reported. We conclude that, while the I⁻-ion is contact adsorbed on the mercury surface, the Li⁺-ion is not.     

Chemical speciation of mercury in natural waters

Improved sensitivity of the cold-vapour atomic absorption method for mercury can be obtained by equilibrating the reduced sample with a small volume of air at 90°C. An automated system has been developed that has a detection limit of 1 ng Hg l^-1. By changing the reducing conditions three species of mercury can be differentiated and determined, inorganic mercury, arylmercury compounds such as phenylmercury(II) chloride, and alkylmercury compounds such as methylmercury(II) chloride. Speciation of mercury in natural waters is possible.     

Instability of mercury in specimens of human urine for external quality assessment

An under-recovery of inorganic mercury added to urine and a wide range of results is observed in quality assessment schemes (EQAS) for trace elements. Furthermore, the under-recoveries are inconsistent suggesting features associated with the urine matrix may make the mercury unavailable for measurement. To investigate the instability of mercury in urine the following experiments were set up: (1) a sample of Hg²⁺ in water with various ‘stabilizers’ added was sent to UK external quality assessment scheme participants. (2) Urine was collected from volunteers who also completed a 3-day food diary. Hg, Ca, Mg, Se, uric acid, phosphate, creatinine, reducing substances and protein were measured. Inorganic mercury was spiked into the urine, stabilizers were added and the mercury determined following storage. The results confirmed under-recovery of mercury in association with the urine matrix. Further investigations of how urinary components affect the measurement of mercury are necessary.     

Uptake of mercury by caged crayfish

An in situ caged crayfish experiment was conducted in the Wabigoon River System, Ontario, Canada to determine the relative importance of food and water pathways for mercury accumulation in crayfish. Two groups of 160 crayfish were suspended in the water column; one at an ucontaminated site, the other at a location with highly elevated total mercury and methylmercury levels in water. Crayfish at each site were divided into two groups. Crayfish were fed either sucker flesh obtained from an uncontaminated lake (low mercury diet) or walleye flesh from contaminated Clay Lake, Ontario, Canada (high mercury diet). After 10 weeks crayfish at both sites fed the high mercury diet had over 20 times mercury accumulation compared to crayfish on the low mercury diet. There was no statistical effects due to sharply elevated water concentrations of total and methylmercury on mercury bodyburdens. This indicated that food was the dominant pathway for mercury accumulation in crayfish.     

Neues Quecksilber-Spektrometer zur Messung von Quecksilberdampf in Luft

Zusammenfassung Ein Atomabsorptions-Spektrometer wird beschrieben, das zur Bestimmung des Quecksilbergehaltes in Luft die Absorption der im vakuumultravioletten Spektralbereich gelegenen Hg-Resonanzlinie 184,9 nm benutzt. Die Kombination einer Hg-Niederdruckdampflampe mit einer Photozelle mit CsI-Kathode gestattet einen Spektrometer-Aufbau ohne Monochromator oder Filter. Zur Messung der HgKonzentration in Gasen wird das Quecksilber einer Probe zunächst auf einem Goldblech gesammelt, durch Ausheizen des Goldes wieder freigesetzt und die Absorption durch die Dampfwolke bestimmt. Das Eichverfahren und Meßbeispiele werden erläutert.

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New mercury spectrometer for the measurement of mercury vapour in air

Summary An atomic absorption spectrometer is described using the absorption of the vacuum ultraviolet resonance line 184.9 nm to determine the amount of mercury in air. The use of a mercury low-pressure discharge lamp combined with a CsI photocell makes it possible to omit monochromator or filter. For measuring the concentration of mercury in all sorts of gases the mercury of the sample is collected on sheet gold. By heating the sheet mercury is set free and the absorption of the mercury vapour can then be measured. The calibration procedure and some analytical results are described.

     

A simple operational relationship between drop-time and interfacial tension at a charged mercury/aqueous solution interface

This paper describes a simple operational relationship between the drop-time of a dropping mercury electrode and the interfacial tension at a charged mercury/aqueous solution interface. An apparatus and technique for measuring drop-times is reported, and examples are given of the fit of experimental drop-times to literature values of interfacial tensions. The operational relationship is independent of temperature in the range 293-313 K.     

Mercury exchange between diphenylmercury and bis(p-chlorophenyl)mercury

Experimental methods for investigating mercury exchange between diphenyl mercury and bis(p-chlorophenyl)mercury have been evaluated and kinetic parameters determined using a novel partition technique. An octahedral transition state has been proposed. The investigation was complicated by a relatively fast reaction rate, and the kinetic interference of impurities or hydrolysis products.     

An MSFIA system for mercury speciation based on an anion-exchange membrane

A new methodology for the in-line preconcentration, clean-up and speciation of mercury by use of an anion-exchange membrane is proposed. The speciation of mercury is based on retention of its tetrachloro complex onto the membrane while organic mercury flows freely through it. A multisyringe is used as a liquid driver and a cold vapour atomic fluorescence detector is employed to ensure a high sensitivity. Organic mercury is decomposed into to inorganic mercury by using a UV lamp. The carrier and reductant streams consist of 1.5% (m/v) hydrochloric acid and 2% (m/v) tin chloride, respectively. Certified reference material DORM-2 was digested with 37% hydrochloric acid and analysed directly without the need for extraction. The proposed system is more environmental friendly than the classical liquid-liquid extraction procedure. Mercury recoveries from spiked samples and the reference material were all close to 100%. An LOD of 14 and 16 ng/L was obtained for total and organic mercury, respectively, both with an RSD less than 1.3%.     

On-line preconcentration and determination of mercury in biological samples by flow injection vapour generation inductively coupled plasma atomic emission spectrometry

An FI-ICP-AES method for the determination of trace levels of mercury in biological samples has been described, which is based on the extraction of the mercury complex with 1,5-bis (di-2-pyridyl)methylene thiocarbonohydrazide (DPTH) on-line into isobuthyl-methyl ketone (IBMK). The organic phase (containing the complex) has been mixed on-line with SnCl₂ in N,N-dimethylformamide. Thus, mercury vapour can be generated directly from the organic phase and separated in a gas-liquid separation device. The detection limit for mercury is 4 ng/ml and the calibration curve is linear at least from 10 to 2500 ng/ml. The relative standard deviation for 10 replicate measurements is ±1% for 100 ng/ml of Hg(II). Results from the analysis of some certified biological reference materials are given.     

Electrodeposition of mercury film on electrodes modified with clay minerals

A new type of carbon paste electrode modified with clay mineral and covered with a mercury film is presented in this work. Electrodeposition of the mercury film was performed on the carbon paste electrode modified with montmorillonite. The mercury film was deposited by both electrodeposition in situ and a preliminary electrodeposition. The pre-deposited film of mercury showed to be suitable for anodic stripping voltammetry. An open-circuit sorption of Cd, Pb, and Cu with subsequent anodic stripping voltammetry exhibited higher current responses of metals. Besides the enhanced sensitivity superior separation of the current responses during a simultaneous stripping of metals is expected to be achieved by means of the newly prepared electrode. Presented at the 57th Congress of Chemical Societies, Tatranské Matliare, 4–8 September 2005.     

Determination of sub-nanogram amounts of mercury by cold-vapour atomic fluorescence spectrometry with an improved gas-sheathed atom cell

An improved gas sheathed cell for the cold-vapour determination of mercury by atomic fluorescence spectrometry is described. Mercury ions in aqueous solution are reduced by tin(II) chloride, and the mercury flushed from solution by argon is discharged from a tube situated adjacent to the spectrometer entrance slit and a mercury electrodeless discharge lamp. A second stream of argon is directed up small capillaries arranged around this outlet tube to provide a laminar sheath of argon around the atom cell. At optimised flow rates, the signal is about 10 times greater than when no laminar sheath is provided. Precision is also improved. The limit of detection (2σ) is 0.01 ng of mercury for a 0.5-ml aliquot of sample (i.e. 20 ng 1^-1). The accuracy of the system is demonstrated by the determination of mercury in NBS Orchard Leaves and in barley seeds. Typically relative standard deviations are in the range 0.6–3%.     

Further developments in the high-precision coulometric titration of uranium

An experimental study of the current efficiency in the coulometric generation of Ti(III), as a function of electrolyte composition, current density and electrode material, has been performed. The cathodes investigated include platinum, mercury and graphite. The first two are suitable for high-precision determination of uranium. The graphite surface is readily poisoned, rendering it useless for high-accuracy work. The use of mercury requires thorough removal of chloride from the system. The precision and error obtained are comparable for both the mercury and platinum cathodes, and are of the order of 50 ppm.