Voltammetric methods for determination of mercury in domestic waste and compost

A voltammetric method for the determination of mercury in domestic waste, compost produced from it and in water extracts of these samples is described. The solid samples have been digested with concentrated acids and the extracts by UV irradiation. Conditions for the voltammetric determination of mercury with a gold disc electrode in samples of very complicated composition have been worked out. To avoid the disturbing influence of copper a special potential — time program has been applied, whereas the disturbing effect of iron has been removed by complexation of Fe(III) with fluoride ions or by medium exchange. The procedure proposed suits very well for determination of mercury in the samples studied. A very low leachability of mercury from compost was found.     

Voltammetric method for the determination of Zn,Cd, Pb,Cu and Ni in interstitial water

To determine heavy metals in interstitial water from Baltic sea sediments a sampling method with subsequent voltammetric determination is described. Copper, lead, zinc and cadmium are determined in the UV-digested samples of interstitial water by differential pulse anodic stripping voltammetry while nickel is determined by adsorption voltammetry. The determination of five metals in one sample in a wide concentrations range is possible using a low cost apparatus. The profiles of the metal concentrations in interstitial water of subsequent layers of sediments, sampled from Puck Bay, Gdańsk Bay, the Bornholm area and the S?upsk area are presented.     

Simultaneous Determination of Seven Toxic Trace and/or Ultratrace Metals in Environmental Plants by Differential Pulse Voltammetry Without Change of Solution and Electrode

Abstract

A simple and reliable procedure simultaneously to determine seven trace and/or ultratrace toxic metals in a single sample of environmental plants has been presented. The procedure is based on the simultaneous determination of Cu, Pb and Cd by differential pulse anodic stripping voltammetry, of Zn and Mn by differential pulse voltammetry and of Ni and Co by differential pulse adsorption voltammetry at the hanging mercury drop electrode. The details of sampling, washing and drying of samples and the approach of digestion and preparation of samples for voltammetric determination have been investigated. The method has been applied to determination of the seven metals in grass and hucerne from different environments.     

Leaching Studies of Inorganic and Organic Compounds from Fly Ash

Fly ash is produced in massive quantities by fossil fuel based power plants and waste incinerators, and contains high levels of potentially toxic chemicals. Various leaching tests exist to determine the available fractions, but the outcome is strongly dependent on the experimental conditions, and these have not yet been harmonised at the international level. In order to test existing protocols for heavy metals, several intercomparisons were organised within the framework of an EU-INCO project "ANALEACH", in which seven institutes from five countries participated. Two existing reference materials were made available for the project and test batches of two new fly ash reference materials were produced. Availability tests, leaching tests and pH-stat tests were studied and critical steps in the procedures were identified. Fly ashes can also contain large amounts of inorganic sulphur and nitrogen compounds, and the determination and leaching behaviour of these compounds were also studied. In one intercomparison for metals, inorganic S and N-compounds were also included. A five-step leaching test was optimised for fly ash in order to link metal fractions to different types of binding. Column leaching experiments were carried out to investigate leaching from fly ash into soil, mimicking the effects of (acid) rain on fly ash deposited on topsoil after atmospheric transport. The major fraction of the leached metal ions was retained by the soil. Also large numbers of organic compounds (including many toxic ones) were identified in fly ash extracts, especially in city waste incinerator ash. Leaching procedures based on ultrasonic extraction were developed for organic compounds and an intercomparison exercise was organised. In a field study at the river Nitra(Slovakia) numerous organic pollutants were found at elevated levels downstream from a major fly ash dump site.     

Voltammetric method for the determination of Zn, Cd, Pb, Cu and Ni in interstitial water

To determine heavy metals in interstitial water from Baltic sea sediments a sampling method with subsequent voltammetric determination is described. Copper, lead, zinc and cadmium are determined in the UV-digested samples of interstitial water by differential pulse anodic stripping voltammetry while nickel is determined by adsorption voltammetry. The determination of five metals in one sample in a wide concentrations range is possible using a low cost apparatus. The profiles of the metal concentrations in interstitial water of subsequent layers of sediments, sampled from Puck Bay, Gdask Bay, the Bornholm area and the Supsk area are presented.     

Ion-exchange resins containing s-bonded dithizone and dehydrodithizone as functional groups : Part 3. Determination of Gold,Platinum and Palladium in Geological Samples by means of a Dehydrodithizone Resin and Plasma Emission Spectrometry

A procedure is described for the determination of gold, platinum and palladium in sulphide ores, concentrates and mattes. The method is based on chromatographic separation and selective elution of precious metals on small resin beds (0.7 × 2.5 cm) of the sorbent P-TD. After roasting, the samples were digested with aqua regia, and the residues fused with sodium peroxide. The acid leaching solutions obtained from both procedures were separately passed through an ion-exchange column. The metals were quantitatively retained after one loading step and eluted by a sequence of 2 M perchloric acid and 5% (w/v) thiourea solution. Preconcentrated Au, Pt and Pd were finally quantified with a d.c. plasma emission spectrometer. The effect of roasting temperature on the recovery of precious metals as well as the efficiency of the aqua regia leaching from the different materials were investigated in detail. Repeated analyses of standard reference samples proved the proposed method to be reliable.     

碱融浸取–离子选择电极法测定固体废物中的总氟

采用氢氧化钠熔融浸取固体废物中的氟,用离子选择电极法测定其中的总氟含量。固体废物样品经氢氧化钠高温熔融后,以热纯水浸取并加入适量的盐酸使溶液呈弱碱性,去除主要干扰离子。测定氟的线性范围为5.00~500μg,线性相关系数r=0.999 6,检出限为12.5 mg/kg。6种类型固体废物样品的加标回收率在90.4%~110.0%之间,测定结果的相对标准偏差为2.3%~4.6%(n=6)。该方法样品预处理简单、重现性好、检出限低,适用于多种固体废物中总氟的测定。     

A new electrochemical method based on transfer at a liquid/liquid interface: Determination of barium and strontium

A new kind of polyoxyethylene ionophore is introduced to facilitate metal ion transfer across a liquid/liquid interface. The transfer of Ba(2+) and Sr(2+), facilitated by polyethylene glycol 400 across the interfaces of water/nitrobenzene and water/1,2-dichloroethane, has been studied in detail by cyclic voltammetry, and a new method for the determination of barium and strontium established. Both metals can be determined by cyclic voltammetry with good selectivity and reproducibility.     

Determination of mobile form contents of Zn, Cd, Pb and Cu in soil extracts by combined stripping voltammetry

The amount of mobile forms of Zn, Pb, Cd and Cu in extracts obtained by treating soil samples with ammonium nitrate were determined by an appropriate combination of anodic and cathodic stripping voltammetry with hanging mercury drop electrode. Every analysis required three mercury drops: on the first one, zinc was determined; on the second, cadmium and lead; on the third, copper was determined. Zinc, lead and cadmium were determined by conventional differential-pulse anodic stripping voltammetry. For copper determination, adsorptive differential-pulse cathodic stripping voltammetry with amalgamation using chloride ions as a complexing agent was applied. The standard deviation of the results was from 1 to 10% depending on the metal content in the sample. Voltammetric results were in good agreement with the AAS analysis. No microwave digestion of soil extracts was necessary.     

Arsenic and heavy metals in leachate from a real landfill and a laboratory landfill

A preliminary study, based particularly on Arsenic and some heavy metals determination (Cd, Cr, Hg and Pb) in three leachate tipologies produced from municipal waste landfill plant, lab-scale aerobic landfill, lab-scale anerobic landfill was undertaken. Leachate was collected and analysed monthly; samples were homogenized and then, all heavy metals were determined after mineralization, except for Hg, determined before mineralization, due to his high volatility. In all samples pH was measured. In general we can say that low concentrations of the elements analyzed were found in all kinds of landfills considered; in particular, in the lab-scale anaerobic reactors, where low pH values have been found, we have a more considerable mobilization of As and the others heavy metals, moreover due to the behaviour of these elements.     

An electrochemical on-field sensor system for the detection of compost maturity

A maturity sensor system was developed, based on the combination of three electrically measured parameters, pH, NH₄⁺ concentration, and phosphatase activity in the water extracts of compost samples. One of these parameters, the apparent phosphatase activity in crude test solutions was determined using screen-printed carbon strips (SPCSs) coated with α-naphthyl phosphate (α-NP) in Nafion film. The phosphatase activity was monitored in connection with differential pulse voltammetry (DPV) with an aliquot (30 μL) of the test solution on SPCS. The phosphatase activity sensor was validated using alkaline phosphatase (ALP) in Tris-HCl buffer (pH 8.0) and acid phosphatase (ACP) in citric acid buffer (pH 5.0). The activity of the spiked enzymes in the water extract of the compost sample could be confirmed with the change of corresponding oxidation peak current signal of the product, α-naphthol. The water extracts of compost samples (n = 24) collected in various composting days were applied to our compost maturity sensor system, and the conventional germination tests. Using multiple regression analysis, the germination index (GI) was expressed by the multi-linear regression equation consisting of pH, NH₄⁺ concentration, and the phosphatase activity. The calculated GI from the regression equation had a good correlation with the measured GI of the corresponding composts (r = 0.873). As a result, we have determined an equation for the determination of the compost stability using our portable sensor system rapidly at the composting site.     

连续流动-分光光度法测定固体废物中氰化物浸出毒性的研究

建立了一种利用连续流动-分光光度法测定固废中氰化物的浸出毒性的方法,当氰化物浓度在0~200μg/L范围内,校准曲线的相关系数r为0.9998;方法的检出限可以达到0.33μg/L;不同浓度样品测定的相对标准偏差低于2.6%,实际固体废物样品加标回收率为96%~103%,方法精密度良好并且准确度较高;通过实际样品测定结果比对,证明方法与传统国家标准方法测定结果有着较高的吻合度,具有良好的应用前景。     

Electrochemical Sample Preparation for the Voltammetric Determination of Heavy-Metal Ions in Wine

An original, simple, and rapid method consuming little labor and eliminating the contamination of a sample and the loss of analytes is proposed for the electrochemical preparation of wine samples. The time of electrochemical sample preparation (ECSP) is no longer than 10 min. A four-electrode single-compartment electrolyzer allows all stages of voltammetric analysis (electrochemical sample preparation, electrochemical preconcentration and determination) to be carried out continuously. The processes occurring at electrodes at different stages of analysis are described. The concentrations of heavy metals determined in wines by stripping voltammetry (SVA) and atomic absorption spectroscopy (AAS) are compared.     

Validation of bismuth film electrode for determination of cobalt and cadmium in soil extracts using ICP-MS

A study is presented on the use of the bismuth film electrode (BiFE) operated in the anodic stripping and the cathodic adsorptive stripping voltammetry (ASV, CAdSV) modes, for the determination of two trace heavy metals (Cd and Co, respectively), in soil extract samples. Two types of BiFE were examined in this study: the in situ prepared BiFE, which was employed in ASV determination of Cd, and the ex situ prepared BiFE, which was used in CAdSV of Co with dimethylglyoxime (DMG) as complexing agent. A series of unpretreated soil extracts with varying Cd and Co concentrations were analyzed, and the results obtained compared to those determined using inductively coupled plasma-mass spectrometry (ICP-MS). The results revealed the suitability of stripping analysis at the BiFE for determination of μg l⁻¹ levels of heavy metals in soil extracts. The promising results obtained here, coupled with the non-toxic nature of bismuth (in comparison to commonly used mercury electrodes employed in stripping analysis), offer great promise in centralized and decentralized analysis of trace heavy metals in complex environmental matrices.     

Simultaneous determination of oxygen, nitrogen and hydrogen in metals by pulse heating and time of flight mass spectrometric method

The inert gas fusion and infrared absorption and thermal conductivity methods are widely used for quantitative determination of oxygen(O), nitrogen(N) and hydrogen(H) in metals. However, O, N and H cannot be determined simultaneously with this method in most cases and the sensitivity cannot meet the requirement of some new metal materials. Furthermore, there is no equipment or method reported for determination of Argon(Ar) or Helium(He) in metals till now. In this paper, a new method for simultaneous quantitative determination of O, N, H and Ar(or He) in metals has been described in detail, which combined the pulse heating inert gas fusion with time of flight mass spectrometric detection. The whole analyzing process was introduced, including sample retreatment, inert gas fusion, mass spectral line selection, signal acquisition, data processing and calibration. The detection limit, lower quantitative limit and linear range of each element were determined. The accuracy and precision of the new method have also been verified by measurements of several kinds of samples. The results were consistent with that obtained by the traditional method. It has shown that the new method is more sensitive and efficient than the existing method.     

Modelling the matrix interference of iron in the multivariate determination of copper by stripping voltammetry Instrument standardization

Two different standardization procedures have been applied in order to minimize the experimental effort necessary to determine copper in presence of iron by differential pulse anodic stripping voltammetry. The significant matrix interference caused by iron in the voltammetric determination of copper has been successfully solved by using partial least squares (PLS) regression. The use of this multivariate regression implies a large number of training set samples, so a standardization method was required. In fact, the standardization methods used have reduced the calibration samples needed in future determinations by up to 75%. Moreover, PLS regression allowed both metals to be determined simultaneously by using an adequate experimental design, without any limitation to their respective concentrations and without the need to know the level of interference.     

水中微量氰化物的测定方法：———异烟酸—巴比妥酸主次波长光度法

根据异烟酸－吡唑啉酮和吡啶－巴比妥酸光度法测定水中氰化物的基本原理，将二者重新组合成异烟酸－巴比妥酸体系，采用主次波长光度法测定。该法具有室温显色，显色所需时间较短，有色溶液稳定，对环境污染小，灵敏度高等优点，其最低检测限为０００１ｍｇ／Ｌ。特别适合于饮用水、生活污水、工业废水中微量氰化物的测定。通过对实际样品分析，与原方法进行比较，结果令人满意。     

Optimization and validation of an automated voltammetric stripping technique for ultratrace metal analysis

A new automated batch method for the determination of ultratrace metals (nanogram per liter level) was developed and validated. Instrumental and chemical parameters affecting the performance of the method were carefully assessed and optimized. A wide range of voltammetric methods under different chemical conditions were tested. Cadmium, lead and copper were determined by anodic stripping voltammetry (ASV), while nickel, cobalt, rhodium and uranium by adsorptive cathodic stripping voltammetry (AdCSV). The figures of merit of all of these methods were determined: very good precision and accuracy were achieved, e.g. relative percentage standard deviation in the 4-13% for ASV and 2-5% for AdCSV.The stripping methods were applied to the determination of cadmium, lead, copper, nickel, cobalt, rhodium and uranium in lake water samples and the results were found to be comparable with ICP-MS data.     

A study of the chemical forms or species of manganese found in coal fly ash and soil

The chemical speciation of manganese of environmental and toxicological interest was undertaken in coal fly ash and soil. Hard coal used in combustion creates considerable quantities of waste ash. The greatest quantities of industrial ashes are stored in the form of waste-heaps, which create a serious problem as the source of inorganic pollution. It is necessary to identify physical and chemical properties of ash, especially when analyzing the pollution of soil by trace metals, which are potentially mobile in environment. In this work, a new analytical method has been developed and used successfully for identification and determination of chemical forms of manganese in coal fly ash and soil. The basic chemical forms of metals contained in the environmental samples (fly ash and soil) can be described by using sequential extraction method. To identify Mn ions, the UV-VIS spectrophotometric method was used by means of comparative analysis of spectrophotometric spectra of appropriate Mn ions in the standard solutions and solutions obtained after extraction. The concentration of manganese in all solutions was determined by the Flame Atomic Absorption method. The experimental approach and analytical method developed in this study appear adequate for this purpose and can therefore be used for similar research.     

Atomic-absorption spectrometric determination of cadmium,lead and zinc in salts or salt solutions by hanging mercury drop electrodeposition and atomization in a graphite furnace

Atomic absorption spectrometric methods are described for the determination of trace amounts of cadmium, lead and zinc in salts or salt solutions. The metals are separated from the salt matrix by electrolysis on a hanging mercury drop electrode, the mercury is transferred to a graphite boat and removed by evaporation, and the metals are determined by atomization. The feasibility of the technique was tested by analysis of sea water and of reagent-grade potassium chloride. For comparison the three metals were also determined in the sea water by stripping voltammetry, good agreement being found.