Search results for "Mercury"

Anodic stripping voltammetric determination of heavy metals in solutions containing humic acids

1994

Various simultaneous effects of humic acids on the current and potential of differential pulse anodic stripping peaks of copper, lead, cadmium and zinc in weakly alkaline and acidic (pH 2) solutions have been investigated and interpreted with regard to metal complexation and the adsorption of humic acid on the mercury electrode. The applicability of the standard additions method for metal quantitation and the experimental conditions for UV-photolysis with a high-pressure mercury lamp have been examined in model as well as real water samples.

<title>Iodine and mercury resonance lamps and their spectrum in far UV</title>

2001

Electrodeless iodine, mercury iodide, and mercury radio- frequency discharge lamps have been made to provide effective sources of atomic spectra for analytical spectroscopy providing powerful resonance radiation of iodine and mercury in the 120-253 nm region. The lamps are required and can be used for spectral calibration, resonance absorption, and fluorescence detection techniques, for investigation of atomic characteristics (e.g., branching ratios) and other purposes where intense monochromatic spectra are needed. Production technology, development, and investigation of the UV and VUV emission are described.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downlo…

Iodine and mercury resonance lamps for kinetics experiments and their spectra in the far ultraviolet

2000

Electrodeless iodine and mercury iodide radio-frequency discharge lamps have been made to provide intense sources of resonance radiation of iodine and mercury in the 183-253 nm region. Production technology and emission spectra in the ultraviolet and vacuum ultraviolet regions are described. Both lamps (iodine and mercury iodide) are designed and used for monitoring the iodine 2P1/2 (206.163 nm) and 2P3/2 (183.038 nm) level population kinetics after flash photolysis of I2 or other precursor molecules in laboratory experiments. The technique is suitable for the investigation of the gas phase reaction kinetics following the photolysis of I2 in the presence of O3.

Coamplexation of mercury(II) compounds by crown ethers in organic media

1991

Complexes between crown ethers having ring sizes of 15–24 atoms and 5 to 8 oxygens with HgX2 species (X = Cl, I, CN, SCN) have been prepared and studied. Interactions of the substituents X bound to mercury with groups or fragments in the crown compound are essential in determining the characteristics and stability of the complexes formed. Complexes with crowns of 18C6 ring sizes are the most favourable except for HgX2 compounds for which the size of X is larger than the macrocycle ring, as is the case for X = CF3.

How Humic Substances Dominate Mercury Geochemistry in Contaminated Floodplain Soils and Sediments

1998

The interaction of mercury (Hg) and humic substances (hs) was studied in floodplain topsoils and surface sediments of the contaminated German river Elbe. An intimate coupling exists between the geochemical cycles of Hg and organic carbon (OC) in this ecosystem. Humic substances exert a dominant influence on several important parallel geochemical pathways of Hg, including binding, transformation, and transport processes. Significant differences exist between the Hg-hs associations in floodplains and sediments. Both humic acids (ha) and fulvic acids (fa) contribute to Hg binding in the sediments. In contrast, ultrafiltration experiments proved that Hg in the floodplain soils is almost exclusi…

Organic derivatives of mercury and tin as promoters of membrane lipid peroxidation.

2008

The toxicity mechanisms of mercury and tin organic derivatives are still under debate. Generally the presence of organic moieties in their molecules makes these compounds lipophilic and membrane active species. The recent results suggest that Hg and Sn compounds deplete HS-groups in proteins, glutathione and glutathione-dependent enzymatic systems; this process also results in the production of reactive oxygen species (ROS), the enhancement of membrane lipids peroxidation and damage of the antioxidative defence system. The goal of this review is to present recent results in the studies oriented towards the role of organomercury and organotin compounds in the xenobiotic-mediated enhancement …

Mercury Speciation in Floodplain Soils and Sediments along a Contaminated River Transect

1998

A novel mercury-specific sequential extraction procedure (SEP) for the assessment of mercury (Hg) speciation in soils and sediments, with emphasis on studying the interaction between Hg and organic matter (OM), was developed and tested. It was applied to determine Hg speciation in floodplain topsoils and surface sediments along the Hg-contaminated part of the river Elbe, and to simultaneously derive some information on the (re)mobilization potentials for Hg from these matrices. The majority of the total Hg in the ecosystem today is bound in the floodplains, which also still geographically reflect the historic emission record. Most of the Hg in both matrices is bound strongly to OM, suggesti…

Evaluation of methylmercury cytotoxicity at intestinal level

2006

Phosphororganische Verbindungen. 611. Polarographische Untersuchung quartärer Phosphonium- und Arsoniumsalze

1969

Summary The half-wave potentials of a number of quaternary phosphonium and arsonium salts are determined under standard conditions, and their dependence on the concentration of the substrate, the temperature, the drop rate, the height of the mercury head, and the concentration of the capillary-active substance (Triton X-100) is established. It is not possible to deduce from the half-wave potentials which ligands, and in what proportion these ligands, are reductively cleaved. The results suggest that ligands are split off as radicals (transfer, of one electron) and as anions (transfer of two electrons).

Validation of Methylmercury Determinations in Aquatic Systems by Alkyl Derivatization Methods for GC Analysis Using ICP-IDMS

2001

Isotope dilution mass spectrometry (IDMS), using an inductively coupled plasma quadrupole mass spectrometer (ICPMS) and a species-specific methylmercury spike was applied to validate the commonly used GC method for methylmercury (MeHg+) determination, which is based on the formation of volatile methylethylmercury by derivatization with NaBEt4. The spike compound, Me201Hg+, was synthesized by reaction of 201Hg-enriched mercury chloride with methylcobalamin. By analyzing different environmental aquatic samples, it was found that in most cases, transformation of MeHg+ into elemental mercury (Hg0) took place. From investigations of synthetic solutions, it could be followed that halide ions are …