Preconcentration and Speciation of Mercury Compounds In Wastewater Using Dithizone Impregnated UHMWPE Membrane and Reverse Phase Liquid Chromatography

Mercury occurs in the environment in various forms such as elementary mercury, inorganic mercury and organic mercury. Recently,extensive damage has been caused to the environment by mercury used in a number of industrial products such as paints, preservatives, paper,pesticides and cosmetics.     

Comparative phytotoxicity of methylated and inorganic arsenic- and antimony species to Lemna minor, Wolffia arrhiza and Selenastrum capricornutum

The alkylation of metalloids through the transfer of methyl groups is an important factor in the biogeochemical cycling of elements like arsenic and antimony. In the environment, many different organic and inorganic forms of these elements can therefore be found in soils, sediments or organisms. Studies that compare the ecotoxicity of these different chemical species however are rare. Therefore, this study aimed to generate toxicity data on two scarcely studied organic compounds of arsenic and antimony, as well as to compare their toxicity to the inorganic species, which are studied so far to a higher extent, in order to improve the environmental effect assessment of these elements. To this purpose, bioassays were performed in which three different aquatic organisms (the floating water plants Lemna minor and Wolffia arrhiza and the green alga Selenastrum capricornutum) were exposed to a concentration series of 3 different arsenic species (sodium arsenite — As(III), sodium arsenate — As(V), and monomethylarsonous diiodide — MMAs(III)) and three different antimony species (antimony potassium tartrate hydrate — Sb(III), potassium hexahydroxoantimonate — Sb(V), trimethylantimony(V) bromide — TMSb(V). The observed effect concentrations demonstrated that the inorganic (III)- and (V)-valent species of arsenic were clearly more toxic than the corresponding antimony species. The highest overall toxicity has been shown by MMAs(III) followed by the inorganic As(III). The highest toxicity of the three tested antimony species has been observed for TMSb(V). The observed differences in effect levels stress the importance once more that speciation must not be ignored in toxicity studies.     

汞的环境生物化学*

汞是人类最早发现和利用的元素之一。汞在环境中以不同化学形态广泛存在,不同的形态具有不同的环境行为和生物效应。从环境中的存在形式,形态分析和对健康的影响等3个方面,对汞元素作了简单介绍。     

高效液相色谱-电感耦合等离子体质谱(ICP-MS)法测定中药材中无机汞、甲基汞、乙基汞

为准确测定中药材中不同形态的汞含量,通过选用人工胃液作为提取液,经水浴加热提取后,以甲醇-乙酸铵为流动相,采用C18反相色谱柱对样品溶液进行分离,最后经电感耦合等离子体质谱(ICP-MS)法测定3种汞形态化合物的含量。建立了中药材中无机汞、甲基汞、乙基汞的高效液相色谱-电感耦合等离子体质谱(HPLC-ICP-MS)法的测定方法,结果表明,3种汞形态化合物在0.5～5 ng/mL范围内均获得良好的线性关系,相关系数均大于0.999。通过加标回收的方法进行准确性评价,加标回收率为75.5%～118%,相对标准偏差RSD为2.4%～9.7%。测定的106批次中药材中,均未检出甲基汞、乙基汞。无机汞检出率为88.7%,合格率为100%。方法能够准确、高效地测定中药材中3种汞形态化合物的含量。106批次中药材中的汞存在形态主要是以无机汞为主。考察的106批次根及根茎类中药材中3种汞形态化合物的含量,积累了基础数据,为中药饮片的质量安全性监管提供技术支撑。     

Determination of Mercury Species in Human Urine by Gas Chromatography-Mass Spectrometry

Monitoring urine mercury levels is helpful to estimating the extent of occupational, environmental and everyday exposure to mercury. Furthermore,mercury speciation has received wide attention all over the world in the past decades because of the close dependence of the toxicity of mercury on its chemical species.     

Renewable silver amalgam film electrodes in electrochemical stripping analysis—a review

The success of a voltammetric sensing procedure depends mainly on the proper choice of the working electrode. This is because its ability to accumulate the analyte determines the sensitivity of the method. The main criterion of the selection of the proper working electrode is the available potential window. A variety of conductive materials have been used for the preparation of working electrodes. Of these, two kinds of mercury electrodes—hanging mercury drop and film—were used because of their excellent voltammetric performance and, in particular, their high overpotential of hydrogen reduction. The significant drawbacks of mercury electrodes, however, are the toxicity of the material and the instability of liquid mercury films. To overcome these disadvantages, less toxic mercury-containing materials have been used, such as amalgams and amalgam film electrodes. This group includes renewable silver amalgam film electrodes used for electrochemical stripping sensing purposes. These electrodes have successfully been applied for anodic, adsorptive, cathodic, catalytic voltammetric, and potentiometric stripping determination of trace amounts of inorganic cations and organic compounds in various natural matrices. In this review, the electrode design, characteristics, and application of two kinds of renewable silver amalgam film electrodes are discussed in detail.     

Subnanogram Determination of Inorganic and Organic Mercury by Helium-Microwave Induced Plasma-Atomic Emission Spectrometry

Abstract

Inorganic and organic mercury were determined by helium-microwave induced plasma-atomic emission spectrometry following cold vapor generation. Whereas only inorganic mercury was reduced by stannous ion in an acidic medium, both inorganic and organic mercury (total mercury) were reduced by stannous ion in the presence of cupric ion in a basic medium. Organic mercury was determined as the difference between total and inorganic mercury. Detection limits for inorganic and organic mercury were 11 and 10 pg, respectively, The accuracy of the proposed method was verified through the determination of inorganic, total and organic mercury in two marine biological standard reference materials, DORM-1 and TORT-1.     

Application of chromatographic and electrophoretic methodology to the speciation of organomercury compounds in food analysis

Trace metals such as mercury, especially its organic compounds, are an important risk to the environment and to man due to their accumulation in the food chain. For this reason, the routine determination of the very toxic methylmercury, and of other organic and inorganic mercury compounds in marine and land animals, vegetables, fruits and fresh water is of increasing importance in health and environmental control programmes throughout the world. The majority of speciation methods for organomercurials involve a series of fundamental steps for the identification and quantification of samples of biological origin: extraction or isolation from the matrix; derivatisation and concentration; detection; separation of different species of interest and of interference. Each of these steps, as part of the chromatographic analysis of MeHg and of other organomercurials is revised in this study using food samples.     

Determination of Mercury in some TCMs (Traditional Chinese Medicines) by ICP-MS and Sepeciation of Mercury Species Using Ion-Exchange Chromatography

Cinnabar, composed mainly of HgS,is often used in Traditional Chinese Medicines as part of the active ingredients in formulated drugs to treat diseases such as epilepsy,sore throat. To gain understanding on the clinical efficacy, safety and toxicity of these TCMs, information regarding not only the total concentrations of the heavy metals, but also their different chemical species is necessary. Therefore, the development of sample treatment and analytical techniques for the accurate determination and speciation of heavy metals in TCM products are of critical importance. The dual objectives of this work are to:(1) develop a leaching procedure using simulated body fluids for bioavailability and toxicity studies, and (2) investigate the possibility of Cinnabar derived mercury to bind with other constitutes in Tian Wan Bu Xin Wan using a sequential extraction scheme.     

高效液相色谱-原子荧光光谱法应用于不同营养级鱼肌中汞的形态分析

汞是环境中最具威胁的元素之一,各形态汞的毒性不同,并且会随食物链的传递积累. 因此,同时检测鱼肌中不同形态的汞含量,并分析其在不同生境及营养级的差异性具有相当重要的研究价值. 通过高效液相色谱-原子荧光光谱联用法改变流动相中甲醇的浓度、光电倍增管负高压、空心阴极灯电流、还原剂及载流的浓度等条件,优化了不同汞形态组分的分离程度和响应值. 在优化的试验条件下,将鱼肌样品经离心、过柱、洗脱等步骤处理后,由液相色谱分离,最终通过原子荧光法检测提取溶液中3种汞形态. 结果表明,二价汞、甲基汞、乙基汞在0.2~10.0 μg/L质量浓度范围内线性关系良好,相关系数均大于0.999 9,方法检出限在0.39~0.82 μg/kg之间,平行样品相对标准偏差(RSD)均小于4.0%. 方法前处理简单,准确度高,适用于鱼肉中汞的形态分析. 方法应用于不同生境、不同营养级的鱼肌样品检测,可观察到不同营养级样品结果明显的差异性及同类样品间的相关性.     

The role of element speciation in environmental and occupational medicine

In order to evaluate the interaction with the environment or to assess absorption, binding mechanisms, reactivity and excretion of elements in humans, element speciation can provide more information than the analysis of element as a whole. Some examples that confirm the importance of speciation depend on the choice of the most appropriate indicator or representative matrix. The determination of As(III), As(V), monomethylarsonic and dimethylarsinic acids can be used to evaluate occupational exposure to As. Exposure to inorganic Hg should be measured by its content in urine, whereas in the case of exposure to alkyl Hg, blood and hair should be considered. Speciation may also be useful in studying element toxicokinetics, since it is well known that hexavalent Cr is taken up more than the trivalent form, and that species of the same metal are differently partitioned in blood. Pentavalent forms of As are absorbed more than trivalent forms, and the organic species of elements are excreted faster than inorganic species. In addition, speciation can play an important role in assessing element toxicodynamics. The toxicity of the three oxidation states of Hg differs considerably; for As a decreasing toxicity from arsenite to dimethylarsinic acid is proposed; for organotin compounds, higher toxicity for ethyl groups than for phenyl groups is reported. However, speciation in biological media is difficult when applied to other elements because of the lack of information on the existence and significance of species whose determination could be valuable. Furthermore, there may be no analytical methods that allow an accurate measurement of the species. The feasibility of speciation in occupational and environmental medicine depends mainly on our capability to solve some problems related to the identification and determination of species and on the demonstration that species measurement represents a clear improvement compared to total element determination.     

Review: Reactive selenium metabolites as targets of toxic metals/metalloids in mammals: a molecular toxicological perspective

Human activities have been contaminating the environment with toxic heavy metal and metalloid compounds. Since the toxicity of one metal or metalloid can be dramatically modulated by the simultaneous ingestion of another, studies addressing the molecular basis of chemical interactions between toxic and essential elements are increasingly important. The intravenous injection of rabbits with selenite and arsenite or with selenite and mercuric mercury resulted in the in vivo formation of the seleno‐bis (S‐glutathionyl) arsinium ion, [(GS)₂AsSe]^?, or a glutathione‐coated mercuric selenide, (GS)₅(HgSe)_core, in blood. The formation of these species (and the formation of a cadmium–selenium species in blood after the exposure of rats to selenite and cadmium) critically involves reactive selenite metabolites, such as GS–Se^? and/or HSe^?, which indicates that these physiologically important metabolites are molecular targets of ingested toxic metals and metalloids. The fate and stability of [(GS)₂AsSe]^? and (GS)₅(HgSe)_core in vivo imply that the chronic exposure of mammals to inorganic arsenic and mercury will cumulatively affect the bioavailability of selenium, which could lead to selenium deficiency. Since selenium deficiency is significantly associated with the etiology of cancer in humans, the GSH‐driven in vivo formation of selenium‐containing metal and metalloid species provides a likely molecular mechanism for the chronic toxicity of environmentally persistent inorganic arsenic, mercury and cadmium. Copyright © 2002 John Wiley & Sons, Ltd.     

Study of an organically modified clay: selective adsorption of heavy metal ions and voltammetric determination of mercury(II)

In this work, a hydrophilic clay, Na-montmorillonite from Wyoming, USA, was rendered organophilic by exchanging the inorganic interlayer cations for hexadecyltrimethylammonium ions (HDTA), with the formulae of [(CH₃)₃N(C₁₆H₃₃)]⁺ ion. Based on fact that organo-clay has high affinities for non-ionic organic molecules, 1,3,4-thiadiazole-2,5-dithiol was loaded on the HDTA-montmorillonite surface, resulting in the 1,3,4-thiadiazole-2,5-dithiol-HDTA-montmorillonite complex (TDD-organo-clay).The following properties of TDD-organo-clay are discussed: selective adsorption of heavy metal ions measured by batch and chromatographic column techniques, and utilization as preconcentration agent in a chemically modified carbon paste electrode (CMCPE) for determination of mercury(II).The main point of this paper is the construction of a selective sensor, a carbon paste electrode modified with TDD-organo-clay, its properties and its application to the determination of mercury(II) ions, as this element belongs to the most toxic metals. The chemical selectivity of this functional group and the selectivity of voltammetry were combined for preconcentration and determination.     

Elemental characterization of coal ash and its leachates using sequential extraction techniques

Over 50 million tons of coal ash are produced annually in North America. Technological improvements in air pollution control have decreased stack emissions but have also increased contaminant concentrations in the ash of coal-fired boiler applications. The leaching of heavy metals and other elements during regulatory tests may cause coal ash ro be classified as hazardous waste, complicating land disposal. The hazardous nature of coal ash remains unclear because current toxicity tests fail to effectively characterize the elemental distribution and chemical solubility of trace metals in the landfill environment. Leaching characteristics of ash samples can be investigated with various laboratory extraction procedures in association with multi-elemental analytical techniques (e.g., neutron activation analysis and inductively coupled plasma-atomic emission spectroscopy). Such methods provide more thorough analyses of coal ash leaching dynamics than the regulatory assessments can demonstrate. Regulatory elements including Ag, As, Ba, Cd, Cr, Hg, Pb, and Se were shown to remain in largely insoluble forms while elements such as B and S leached at higher levels. Experimental results may assist operators of coal-fired boiler industries in selecting coal types and disposal options to curtail the leaching of potentially toxic inorganic contaminants.     

Mercury transformations in chemical agent simulant as characterized by X-ray absorption fine spectroscopy

Chemical analyses of U.S. stockpiled mustard chemical warfare agent show some agent destined for destruction contains mercury [L. Ember, Chem. Eng. News 82 (2004) 8]. Because of its toxicity, mercury must be removed from agent prior to incineration or be scrubbed from incineration exhaust to prevent release into the atmosphere. Understanding mercury/agent interactions is critical if either atmospheric or aqueous treatment processes are used. We investigate and compare the state of mercury in water to that in thiodiglycol, a mustard simulant, as co-contaminants are introduced. The effects of sodium hypochlorite and sodium hydroxide, common neutralization chemicals, on mercury in water and simulant with and without co-contaminants present are examined using X-ray absorption fine spectroscopy (XAFS).     

Speciation of mercury in soil and sediment by selective solvent and acid extraction

In order to characterize the mercury hazard in soil, a sequential extraction scheme has been developed to classify mercury species based on their environmental mobility and/or toxicity for either routine lab analysis or on-site screening purposes. The alkyl mercury species and soluble inorganic species that contribute to the major portion of potential mercury toxicity in the soil are extracted by an acidic ethanol solution (2% HCl+10% ethanol solution) from soil matrices as "mobile and toxic" species. A High-Performance Liquid Chromatography (HPLC) system coupled with Inductively Coupled Plasma Mass Spectrometry (ICP-MS) detection has been developed to further resolve the species information into soluble inorganic species (Hg(2+)), methylmercury(II) (MeHg(+)) and ethylmercury(II) (EtHg(+)) species. Alternatively, these species can be separated into "soluble inorganic mercury" and "alkyl mercury" sub-categories by Solid-Phase Extraction (SPE). A custom Sulfydryl Cotton Fiber (SCF) material is used as the solid phase medium. Optimization of the SCF SPE technique is discussed. Combined with a direct mercury analyzer (DMA-80), the SCF SPE technique is a promising candidate for on-site screening purposes. Following the ethanol extraction, the inorganic mercury species remaining in soil are further divided into "semi-mobile" and "non-mobile" sub-categories by sequential acid extractions. The "semi-mobile" mercury species include mainly elemental mercury (Hg) and mercury-metal amalgams. The non-mobile mercury species mainly include mercuric sulfide (HgS) and mercurous chloride (Hg(2)Cl(2)).     

On the uniforming of the atomization process for inorganic and organic mercury in graphite furnace atomic absorption spectrometry

The analytical performance of Pd, Au, Rh, Ir and their mixtures used as chemical modifiers has been investigated for mercury determination by graphite furnace atomic absorption spectrometry. The aim of this work was to evaluate whether chemical modification assures uniform atomization of analyte independent of its chemical form; mercury was used for this study. The investigations were performed for mercury introduced in the form of inorganic Hg(II) or organic PhHg(I). The best conditions, i.e. maximum pyrolysis temperature (450 °C), lowest temperature for atomization (1100 °C), provided almost the same sensitivity for both forms of mercury when a thermally reduced mixed modifier composed of Pd/Rh was used. The accuracy of the selected conditions was evaluated by a recovery test for various natural waters.     

Combustion of Waste Waters Containing Organic Alkaline Salts

Abstract

The biological treatment of waste waters from chemical industry containing organic and inorganic salts causes problems because these materials inhibit the metabolic activity of the bacteria. One possible and economically feasible way to convert the organic materials into less toxic forms is a thermal oxidation process, which can take place either in a fluidized bed combustor or in a vertical combustion chamber.

The process is described and parameters of the process are discussed. Results from particle measurements on a vertical combustion chamber for the combustion of various artificial waste waters are presented. The chemical analysis of the particulate matter from different stages of the process allows a detailed characterization of the decomposition of the organic material. Conclusions are drawn both with respect to the process and the environment.     

大气颗粒物中砷及其形态的研究进展

大气颗粒物中毒性准金属元素砷及其形态含量变化引起的环境健康问题受到了广泛关注。由于工业生产和煤燃烧等人类活动,砷普遍存在于多种环境介质中。排放到大气中的砷能够随气流进行长距离迁移,致使一些偏远区域大气中的砷含量明显超出欧盟的限制标准(6 ng/m3)。砷的毒性表达很大程度依赖其存在种态,无机砷毒性大于有机砷,且砷(Ⅲ)的毒性明显强于砷(Ⅴ)。本文概述了大气中砷的来源,并选取自2000年来的代表性成果比较了不同国家及不同功能区大气砷的含量变化,同时对1975年来多数关于大气颗粒物中砷形态变化特征的研究进行了评述。     

Detoxification of mercury in the environment

In this study, a green chemistry approach was developed as an option for remediation of toxic mercury in the environment. Twenty mercury compounds were treated with an environmentally friendly agent cyclodextrin to produce stable non-toxic mercury in soil and water. The binding efficiency was determined using high performance liquid chromatography with diode-array detection. The stability of the cyclodextrin mercury complexes toward environmental microorganisms in water was estimated under OECD guidelines using gas chromatography–mass spectrometry. The toxicity of the cyclodextrin mercury compounds to terrestrial organisms was investigated by use of internationally recognized toxicity methods using mercuric acetate as a model contaminant. Key process conditions, for example pH, temperature, and amount of detoxifying agent were investigated and found to have significant effects on the toxicity of mercury. It was found that organic and inorganic mercury pollutants could be mineralized in the environment with cyclodextrins. The bound mercury compounds resisted biodegradation and were found to be non-toxic to environmental microorganisms under laboratory conditions.