Determination of copper, nickel, zinc, cobalt and manganese in seawater by chelation ion chromatography

Preconcentration and determination of trace elements in seawater by chelation ion chromatography (CIC) was studied. For the retention of metal ions (0.25–0.30 M), ammonium acetate (at pH 4.8–5.1) and macroporous iminodiacetate chelating resin were used. This system (CIC) permits trace and ultra-trace determination of metals in a variety of complex matrices, in particular those with a high content of alkali and alkaline earth metals. Detection limits range from 0.1 to 0.5 ng. Satisfactory results are obtained in the range 0.05–0.5 μg/1 when 60 ml of sample are preconcentrated. In this work the contents of zinc, copper, nickel, cobalt and manganese in seawater from the Venice lagoon are presented. The results obtained by chelation ion chromatography are compared with those obtained using preconcentration of metals with dithizone and ammonium pyrrolidinedithiocarbamate in chloroform and analysed by graphite furnace atomic absorption spectrometry.     

Extraction of organic acids by ion-pair formation with tri-n-octylamine : Part 4. Influence of organic phase composition

Synthetic food dyes are extracted by ion-pair formation with tri-n-octylamine. Mixed organic phases are used, consisting of mixtures of hexane with one of the following solvent modifiers: chloroform, dichloromethane, methyl isobutyl ketone, butyl acetate or pentanol. Logarithmic plots of the distribution ratio versus the volume fracton of the solvent modifier are linear for dichloromethane, chloroform and pentanol. The efficiency of the solvents is classified as follows: dichloromethane > pentanol > chloroform > methyl isobutyl ketone > butyl acetate > hexane. The addition of pentanol to chloroform provides nearly quantitative recovery for hydrophilic solutes.     

NEW LIPOPHILIC BISPOCKET-PORPHYRINS FOR CHEMOTHERAPY OF CANCER (PART I); PREPARATION AND PROPERTIES OF 5,10,15,20-TETRAKIS(3′,5′-DI-t-BUTYLPHENYL) PORPHYRIN METAL COMPLEXES1

Abstract

A series of highly lipophilic bis-pocket porphyrins, 5,10,15,20-tetrakis(3′, 5′-di-t-butylphenyl)porphyrin with five metals (copper(II), nickel(II), zinc(II), cobalt(II), and iron(III)), have been prepared and characterized on the basis of electronic, infrared and ¹H NMR spectra. Although electronic spectra of these porphyrins are substantially the same as their prototype tetraphenylporphyrin complexes of the respective metals, their solubility in common organic solvents such as chloroform, benzene, and hexane is dramatically enhanced.     

Influence of the solvent on the extraction of copper(II) from nitrate medium using salicylideneaniline

Different solvents including cyclohexane, dichloromethane, chloroform, toluene, 1-octanol, and methyl isobutyl ketone (MIBK) have been evaluated in extracting copper(II) from nitrate medium by salicylideneaniline. Extracted species differs from solvent to solvent: CuL₂ in cyclohexane, toluene, 1-octanol, and methyl isobutyl ketone. However, in dichloromethane or chloroform, there are two complexes of the type CuL₂ and CuL₂(HL). The extraction constants and percentage of extraction (%E) are calculated for different solvents. Solvent played an important role in recovering copper(II) from the aqueous solution, thus affecting the extraction equilibrium and extraction efficiency. The nonpolar solvent showed better performance than the polar solvent. The maximum extraction efficiency was 85.75% at pH?=?4.5, which was from cyclohexane.     

Stability and extraction features in the determination of Irganox-1330 in a polyalkene copolymer

The determination of Irganox-1330 in a polypropene/polyethylene copolymer is described. The unstable antioxidant can be extracted from the copolymer without degradation at refluxing temperature by using decalin, hexane, chloroform or tetrahydrofuran if adequate protection is provided. The time needed for quantitative extraction is 30 min if the particle size of the polymer is <1.0 mm for any of the solvents. The standard-addition procedure described provides accurate results even when the sample is extracted after being immersed directly in the extracting solvent. For practical purposes, hexane is the preferred extractant. A modified direct-phase high-performance liquid chromatographic system provided a fast, sensitive and stable means of completing the determination.     

Evaluation of an ultrasonic nebulizer-membrane separation interface (USN-MEMSEP) with ICP-AES for the determination of trace elements by solvent extraction

The introduction of volatile organic solvents and metal organic complexes into an inductively coupled plasma (ICP) is problematic due to overloading and pyrolysis effects. These include carbon built up in the torch and spectral interferences. As a consequence, solvent extraction as a method for preconcentrating trace metals for the determination by ICP has been limited. In this report a commercial ultrasonic nebulizer-membrane separation interface (USN-MEMSEP) for the direct introduction and separation of organic solvents using ICP atomic emission spectrometry (AES) and a sequential spectrometer has been evaluated for solvent extraction of chelated trace metals. The ability of the MEMSEP to separate volatile organic flows from metal aerosols has been demonstrated by determining the recoveries of several transition metals in an oil-based methyl-isobutyl ketone (MIBK) standard relative to an aqueous solution. However, low recoveries of several metal chelates have been found evidently due to the volatilization of the organic metal species at the boiling point of MIBK (160° C). Moreover, the multielement capability and limits of detection have been limited due to sequential atomic emission detection. Advantages of the technique include enhanced limits of detection (LODs) and reduced plasma and spectral interferences.     

Evaluation of an ultrasonic nebulizer-membrane separation interface (USN-MEMSEP) with ICP-AES for the determination of trace elements by solvent extraction

The introduction of volatile organic solvents and metal organic complexes into an inductively coupled plasma (ICP) is problematic due to overloading and pyrolysis effects. These include carbon built up in the torch and spectral interferences. As a consequence, solvent extraction as a method for preconcentrating trace metals for the determination by ICP has been limited. In this report a commercial ultrasonic nebulizer-membrane separation interface (USN-MEMSEP) for the direct introduction and separation of organic solvents using ICP atomic emission spectrometry (AES) and a sequential spectrometer has been evaluated for solvent extraction of chelated trace metals. The ability of the MEMSEP to separate volatile organic flows from metal aerosols has been demonstrated by determining the recoveries of several transition metals in an oil-based methyl-isobutyl ketone (MIBK) standard relative to an aqueous solution. However, low recoveries of several metal chelates have been found evidently due to the volatilization of the organic metal species at the boiling point of MIBK (160° C). Moreover, the multielement capability and limits of detection have been limited due to sequential atomic emission detection. Advantages of the technique include enhanced limits of detection (LODs) and reduced plasma and spectral interferences.     

Solvent extraction of N-Cyclohexyl-N-Nitrosohydroxylamine (cnha) into some organic solvents and of the Cu(II)-cnha complex into methyl isobutyl ketone

The distribution equilibria of N-cyclohexyl-N-nitrosohydroxylamine (cnha) in the water-chloroform, water-hexane, water-methyl isobutyl ketone (MIBK) and water-isopentyl alcohol systems, and of the Cu(II)-cnha complex in the water-MIBK system have been studied. From the distribution data the dissociation and distribution constants of the reagent have been calculated; their values are pK(a) = 5.55 +/- 0.10; log K(DR) = 2.46 +/- 0.05 (chloroform), 1.76 +/- 0.11 (MIBK), 1.06 +/- 0.07 (hexane) and 1.48 +/- 0.06 (isopentyl alcohol). In the same way the values of the distribution and stability constants of the Cu(II) complex have been obtained; log K(DC) = 3.51; log beta(1) = 7.23 +/- 0.10 and log beta(2) = 12.00 +/- 0.08. For the determination of cnha in the aqueous phase saturated with MIBK, a spectrophotometric method based on the coloured complex formed by the reagent with Fe(III) has been established. Finally, an analytical method for Cu(II) by atomic-absorption spectrometry after its extraction with cnha into MIBK, is proposed. Its detection limit is 4.6 mug l ., its precision +/- 2.1% and its accuracy 97.5%. This method has been applied to the determination of the copper content in the surface water of the Congest River of Catalonia (Spain).     

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.     

Determination of trace elements in fly ash samples by FAAS after applying different digestion procedure

The fly ash samples obtained from Kangal Power Plant were prepared for FAAS analysis by a new approach. The trace elements of the fly ash samples were leached with appropriate solvents under suitable conditions. The leaching method is known as an effective technique for substances dissolving very hard and refractory materials. The leaching effects of solvents and their mixtures were investigated on fly ash samples that are used largely in analysis of soil and sediment samples.The fly ashes mainly consist of glassy aluminosilicates. The major components of the samples are SiO₂, Al₂O₃, CaO and Fe₂O₃. Therefore, decomposition of the silicate lattice of the fly ash is required for liberation of trace elements. The dissolution process can be completed by using a mineral acid such as concentrated HCl. This technique has an advantage that the fly ash can be dissolved without any oxidation at room temperature.Maximum element recoveries were obtained by the procedure of 37% HCl leaching after the samples were treated with 2.0 ml of concentrated HF. It was also observed that maximum mass loss occurred in this procedure. The effect of the four leaching reagents, which are HCl, HNO₃, HClO₄ and HNO₃ + HClO_4, were investigated on fly ash samples that were treated with concentrated HF. An optimum leaching method was determined based on the confidence of analytical results and element recovery rates.     

(Liquid + liquid) equilibria of the (water + propionic acid + Aliquat 336 + organic solvents) at T = 298.15 K

In this work, trioctyl methyl ammonium chloride (Aliquat 336) was studied for its ability to extract propionic acid at various amine concentrations. The extraction of propionic acid with Aliquat 336 dissolved in five single solvents (cyclohexane, hexane, toluene, methyl isobutyl ketone, and ethyl acetate ) and binary solvents (hexane + MIBK, hexane + toluene, and MIBK + toluene) was investigated under various experimental conditions. The loading factors Z, extraction efficiency E and overall particular distribution coefficients were determined. All measurements were carried out at T = 298.15 K. The obtained results and the observed phenomena were discussed by taking into consideration the mechanism of extraction and the concentration of the interaction product in the aqueous phase.     

Determination of Fe and Zn in biological samples by radiochemical neutron activation analysis

Radiochemical NAA methods have been developed for the simultaneous determination of Fe and Zn in biological samples. The method involves reactor irradiation, dissolution in 3M HCl and solvent extraction followed by counting on a scintillation gamma-ray spectrometer. Iron was separated with aqueous cupferron and extracted into chloroform while Zn was extracted with 2-thenoyl trifluoroacetone (TTA) into methyl isobutyl ketone (MIBK). Reaction conditions such as pH and the effect of solvents and various ions were studied using tracer activities. The methods have been employed for trace level determination of Fe and Zn in NBS, SRMs, Bowen's Kale, IAEA CRMs and other plant leaves.     

燃煤电厂异相凝并飞灰重金属淋滤特性

采集了燃煤电厂的异相凝并后飞灰，分析了其物理化学特性。并通过淋滤实验研究了飞灰中重金属As、Se、Pb的环境稳定性。结果表明，凝并飞灰的粒径峰值为138.04 μm，而粉煤灰为60.26 μm；凝并后细颗粒凝聚成了较大的颗粒；凝并飞灰中重金属As、Se、Pb含量均高于同工况下粉煤灰中的含量，且后序脱硫环节所产生石膏中重金属的含量有所下降；批淋滤实验研究结果表明，凝并飞灰中的重金属浸出能力受淋滤液的pH值影响较大，温和环境和碱性条件抑制了As的浸出，酸性和碱性条件抑制了Se的浸出，而碱性条件抑制了Pb的浸出。柱淋滤实验研究结果表明，在酸性溶液和水溶液中，凝并飞灰的重金属浸出能力均受到了抑制。     

N,N'-disalicylidene-1,3-diaminopropane as a selective chelating titrant for copper(II)

This study was carried out to develop a new complexometric titration method for determination of copper. For this purpose, the standard solutions of copper(II) (10(-3)-10(-5) M) were potentiometrically titrated using N,N'-disalicylidene-1,3-diaminopropane (Schiff base) as titrant and copper(II)-selective electrode for end-point indication in both ammonium acetate and ammonia/ammonium chloride buffer media. The stoichiometry of titration reaction and interference effects of some metal ions on titration of copper were discussed. There was a good agreement between the results obtained by the proposed titration method and ethylenediaminetetraacetic acid (EDTA) titration method. The accuracy and precision of Schiff base method were tested by five replicate determinations both on the standard solution of copper(II) and standard reference materials. The results have indicated that the percentage of copper in alloys can be safely determined by using the Schiff base method without interference from many other metals in alloys.     

室温离子液体催化正己烷异构化反应的研究

由无水三氯化铝与盐酸三乙胺按照不同摩尔比合成了具有不同酸度的室温离子液体,并考察了其酸性以及对正己烷异构化反应的催化性能。结果发现,随着离子液体合成时AlCl3比例的增大,离子液体的酸性增强,且离子液体2AlCl3/Et3NHCl对正己烷异构化显示出优良的催化性能。针对离子液体2AlCl3/Et3NHCl,考察了反应时间、反应温度和催化剂用量（剂油体积比）对正己烷异构化反应的影响。结果表明,反应条件对异构烷烃选择性的影响不大,但是对原料转化率、异构烷烃产率和液体收率有较大的影响。离子液体催化正己烷异构化的最佳反应条件,反应温度为50℃,反应时间为45min,剂油体积比为1∶1。     

Study of the absorption spectra and ionic equilibria of cationic-anionic polymethine dyes

The absorption spectra of a number of cationic-anionic polymethine dyes in polar, low-polarity, and nonpolar solvents were studied. It was established that in polar solvents the absorption spectra represent the sum of the absorption spectra of the cation and anion, whereas in nonpolar and low-polarity solvents, in many cases the appearance of a short-wave absorption band is observed, due to interaction of the chromophores of the cation and anion in ion pairs. In solvents of intermediate polarity (for example, in chloroform and ethyl acetate), a concentration dependence of the absorption spectra is observed, determined by the equilibria of ionic dissociation. The ionic dissociation constants of a number of cationic-anionic dyes in chloroform and ethyl acetate were determined by a conductometric method. The thermodynamic data obtained are compared with the spectral data.N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, 117977 Moscow. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 11, pp. 2524–2532, November, 1992.     

Determination of cadmium by differentialn pulse anodic-stripping voltammetry after salting-out extraction into acetonitrile

A selective and specific method is presented for anodic-stripping voltammetric determination of cadmium after extraction with 0.1Mtetrabutylammonium iodide solution in acetonitrile from aqueous ammonium sulphate solutions. The detection limit of this method is 0.2 ng ml (in the acetonitrile extract). Interference from matrices or large amounts of elements reduced at more positive potentials can be eliminated by prior extraction. The method has been applied to trace analysis for cadmium in zinc, lead and indium metals, and some inorganic salts.     

<Emphasis Type="Italic">N,N</Emphasis>-dibutylhydrazide of octanoic acid as an extragent for the extraction of copper(II) from ammonium media

The solubility and the coefficient of copper(II) distribution between hexane and aqueous phase of N,N-dibutylhydrazide of octanoic acid were studied. The effects of ammonium, Co(II), Ni(II), and Zn(II) salts on the copper(II) extraction was studied. The extraction isotherm was constructed and the constant of copper extraction from ammonium solutions was calculated. The capacity of the organic phase with respect to copper and the conditions of its reextraction were determined.     

Chemical Characterization of Silage Effluents and their Influence on Soil Bound Heavy Metals

Abstract

Silage effluents, generated during silaging of various crops, are produced in high amounts in cattle breeding farms. Due to their acidity and high content of dissolved organic matter, they are causing disposal problems. On the other hand, their ability to mobilise soil bound trace elements (i.e. heavy metals) might be useful for the decontamination of polluted soils.

With an aim to perform metal leaching studies, silage effluents from various ensiled crops (maize, rape, grass, clover, sugar-beet leaves) were collected from Bavarian farms and analysed for their main inorganic and organic constituents. Important TOC sources (TOC concentrations from 13.9 to 53.6 gl^?1) are short chain aliphatic acids (concentrations between 235 and 638 mM·D1^?1; predominant compound: lactic acid), amino acids (ranging from 22.8 to 151 mM·D1^?1) and polypeptides (concentrations from 3.8 to 20.0 g·D1^?1).

The release of heavy metals from two adsorbents (bentonite and peat) and from a polluted soil under the influence of silage effluents was studied in batch tests. The leaching efficiencies for the soil bound metals increase following the order: sugar-beet leaves < clover < maize < rape < grass. The extraction rates obtained with grass silage juice are: Cd 74.7%, Zn 55.7%, Cu 53.5%, Ni 38.9%, Cr 12.7% and Pb 8.9%. After neutralisation the leaching rates dropped, with the exception of copper.     

Nanostructure Restoration of Thermally Reduced Graphene Oxide Electrode upon Incorporation of Nafion for Detection of Trace Heavy Metals in Aqueous Solution

High performance reduced graphene oxide (RGO)‐Nafion (N) thin film electrodes coated on silicon (Si) substrates (RGO‐N/Si) were successfully developed through thermal reduction of GO‐N without delamination from the substrates. The restoration of the RGO‐N nanostructure upon the addition of Nafion was proven by Raman spectroscopy (RS) and field emission scanning electron microscopy, and the restoration mechanism of the RGO‐N nanostructure was proposed. Through the investigation using x‐ray photoelectron spectroscopy (XPS), the polyfluorocarbon from Nafion possessed a function that could prevent the delamination of the RGO sheets from the substrates during the thermal reduction. The RGO‐N/Si samples were later used for the determination of trace heavy metals, such as divalent lead, cadmium and copper ions (Pb²⁺, Cd²⁺ and Cu²⁺, respectively) using square wave anodic stripping voltammetry in a 0.1 M acetate buffer solution (pH 5). Based on the electroanalytical measurements, the RGO‐N/Si samples exhibited a highly linear behavior in the detection of Cd²⁺, Pb²⁺ and Cu²⁺ over the concentration range of 50 nM to 300 nM with detection limits at nM levels. In addition, the RGO‐N/Si samples presented good recoveries of target metals in tap water samples.