A sensitive optical element for mercury(II)

A transparent polymethacrylate matrix modified with copper dithizonate was used to determine mercury(II). Optimum conditions for modifying the polymethacrylate matrix with copper dithizonate were found, and its reaction with mercury(II) in model solutions was studied.     

Sorption-spectrophotometric determination of iron(II, III) with the use of organic reagents immobilized in a polymethacrylate matrix

The interaction of iron(II) with 2,2′-dipyridyl and 1,10-phenanthroline immobilized in a polymethacrylate matrix was studied. The optimum conditions of the complexation of iron(II) with the immobilized reagents and the chemical analytical properties of the complexes in the polymethacrylate matrix were determined. A sorption-spectrophotometric procedure was developed for the determination of iron(II) and the total of iron(II, III) after the reduction of iron(III) by ascorbic acid. The procedure with 2,2′-dipyridyl was used for the analysis of samples of tap, well, and mineral water and a solution of glucose.     

Flow-injection determination of copper(II) based on its catalysis on the redox reaction of cysteine with iron(III) in the presence of 1,10-phenanthroline

A redox reaction of cysteine with iron(III) proceeds slowly in the presence of 1,10-phenanthroline (phen). However, this reaction is accelerated in the presence of copper(II) as a catalyst, producing an iron(II)-phen complex (lambda(max)=510 nm). A sensitive spectrophotometric flow-injection method is proposed for the determination of copper(II) based on its catalytic action on this redox reaction. The dynamic range was 0.1-10 ng ml(-1) of copper(II) with a relative standard deviation of 1.0% (n=10) for 1.0 ng ml(-1) of copper(II) at a sampling rate of 30 h(-1). The detection limit (S/N=3) is 0.04 ng ml(-1). The proposed method was successfully applied to the determination of copper in river water as a certified reference material.     

Catalytic flow-injection determination of sub-ppb copper(II) using the redox reaction of cysteine with iron(III) in the presence of 2,4,6-tris(2-pyridyl)-1,3,5-triazine.

A kinetic-catalytic spectrophotometric flow-injection method was developed for the rapid and sensitive determination of trace amounts of copper(II). The method is based on the catalytic effect of copper(II) on the redox reaction of cysteine with iron(III). Iron(II) produced by the catalytic reaction reacts with 2,4,6-tris(2-pyridyl)-1,3,5-triazine (TPTZ) to form the iron(II)-TPTZ complex (lambda(max) = 593 nm). By measuring an absorbance of the complex, one could determine 0.05-8 ppb copper(II) with the relative standard deviations (n = 10) of 1.6%, 1.3%, and 0.8% for 0.5 ppb, 1 ppb, and 2 ppb copper(II), respectively. The limit of detection (S/N = 3) was 0.005 ppb. The sample throughput was 30 h(-1). The proposed method was successfully applied to the determination of copper in natural water and serum samples.     

Analytical reactions of 5-amino-orotic acid

The potential of 5-amino-orotic acid (AOA) for spectrophotometric determination of metal ions is explored. Only the reactions with copper(II), cobalt(II) and osmium(VIII) are sensitive and suitable for this purpose. Ternary complexes of copper(II) formed with AOA and ammonia or pyridine can also be used for photometric determination of the metal and given better sensitivity and selectivity than the binary complex. Optimum conditions for determination of all the three metal ions have been established.     

A comparison of some pyridyl-substituted pyrazines as analytical reagents

A comparative study of six 2-pyridyl and 2-(6-methyl-pyridyl) derivatives of pyrazine as chromogenic reagents of the ferroin and cuproin types has established 2,3,5,6-tetrakis(2'-pyridyl)pyrazine as a highly sensitive reagent for iron(II); 2,3-bis(2'-pyridyl)-5,6-dihydropyrazine and 2,3-bis[2'-(6'-methyl pyridyl)]-5,6-dihydropyazine both show high sensitivity and characteristic high selectivity in their reactions with iron(II) and copper(I) respectively-the reaction with copper(I) being almost as sensitive as that given by bathocuproine. The ease with which the highly coloured metal chelates can be extracted into immiscible solvents to give stable solutions makes these reagents useful for the determination of traces of iron and copper.     

Determination of Copper in Water by Ionic Liquid Based Microextraction and Chemiluminescence Detection

A versatile, sensitive, and green method based ultrasound-assisted, temperature-controlled, dispersive liquid–liquid microextraction with an ionic liquid and chemiluminescence detection was used for the determination of copper(II) at the ultra-trace level. After complexation by dithizone, copper(II) was extracted into the ionic liquid. Using high temperature and ultrasonic agitation, the copper complex easily migrated into the ionic liquid phase because of the larger contact area. After back extraction, the determination was performed by chemiluminescence based on the catalyzing effect of copper(II) on the decomposition of hydrogen peroxide with rhodamine B. Important parameters that affected the extraction efficiency and chemiluminescence intensity were optimized. Under the optimum conditions, a limit of detection for copper of 0.8 ng L^?1 was obtained with a linear calibration relationship. The method was applied to analyze environmental water samples for copper(II) with satisfactory results.     

Spectrophotometric determination of copper(II) at low mug l(-1) levels using cation-exchange microcolumn in flow-injection

A simple spectrophotometric flow-injection method is reported for the highly sensitive and fast determination of copper(II). The method is based on the formation of coloured Cu(II)-(4-methylpiperidinedithiocarbamate)(2) complex when the copper solutions are introduced into a tertiary reagent stream containing 4-methylpiperidinedithiocarbamate. The coloured complex is then selectively monitored at 435 nm. To increase interactions between copper(II) and colour forming reagent and preconcentrate of copper(II), a microcolumn containing strong cation exchange resins was placed between injection manifold and spectrophotometer. The system required no mixing chamber and allowed a sample throughput >60 sample h(-1). The calibration graph was linear in the range 5-100 mug l(-1). The detection limit was <0.5 mug l(-1) for 20 mul injection volume of copper(II) ion solution. The developed method was applied to environmental, copper processing water, and ore samples.     

meso-四(3-氟-4-磺酸基苯基)卟啉的合成及微分分光光度法同时测定痕量铜锌

本文报道一种新的高灵敏度水溶性卟啉显色剂meso-四(3-氟-4-磺酸基苯基)卟啉的合成方法. 研究了该试剂与Cu(II)、Zn(II)的反应条件. 在PH6.4的HOAc-NaOAc缓冲介质中, Hg(II)催化下, 室温反应30min即完成. 采用四阶微分分光光度法可同时测定痕量Cu(II)、Zn(II). 表观微分摩尔吸光系数分别达8.13×10^5和1.59×10^6. 本方法灵敏度高, 选择性好, 可不用分离直接测定茶叶、血液等样品中痕量Cu(II)、Zn(II), 操作简便.     

Diffusion-layer model for copper solid-state chalcocite membrane electrode; sensitivity to copper(II) ions

The diffusion-layer model for the chalcocite (Cu(2)S) membrane electrode is discussed. It is equivalent to a simpler model based on exchange reactions at the electrode surface. The chalcocite is sensitive to copper(I) and copper(II) ions and the theoretically predicted response is in good agreement with experimental data. The membrane is a conductor, but this does not significantly affect its function as an ion detector. The limitation of the electrode is the membrane solubility as shown when Cu(II) ions in contrast to copper(I) ions are strongly complexed.     

Extraction and spectrophotometric determination of copper with thiobenzoylacetone (3-mercapto-1-phenylbut-2-en-1-one)

The copper(II)-thiobenzoylacetone complex, extracted into benzene, is used for photometric determination of copper at 410 nm after excess of reagent has been removed by scrubbing with a buffer at pH12. The extraction is quantitative over a broad pH range (3.5-9.5). The method is highly sensitive for the determination of copper.     

Indirect Determination of Trace Copper(II) by Adsorptive Stripping Voltammetry with Zincon at a Carbon Paste Electrode

Traces of copper(II) can be determined by adsorptive stripping voltammetry using 2‐carboxy‐2′‐hydroxy‐5′‐sulfoformazyl benzene (Zincon) as complex forming reagent. First in phosphate buffer pH 6.4, copper(II)‐Zincon complex was adsorbed on carbon paste electrode (CPE) with an accumulation potential of 0.6 V. Following this, adsorbed complex was oxidized and detected by differential pulse voltammetric (DPV) scan from 0.6 to 1.0 V. The effective parameters in sensor response were examined. The detection limit (DL) of copper(II) was 1.1 μg/L and relative standard deviations (RSDs) for 10 and 200 μg/L Cu(II) were 1.81 and 1.03%, respectively. The calibration curve was linear for 2–220 μg/L copper(II). The resulting CPE does not use mercury and therefore, has a positive environmental benefit. The method, which is reasonably sensitive and selective, has been successfully applied to the determination of trace amount of copper in water and human hair samples.     

Adsorptive stripping voltammetric determination of copper(II) ion using phenyl pyridyl ketoneoxime (PPKO)

A sensitive and selective procedure is presented for the voltammetric determination of copper(II) ion. The procedure involves an adsorptive accumulation of Cu2+-PPKO on a hanging mercury drop electrode, followed by a stripping voltammetric measurement of reduction current of adsorbed complex at about -0.30 V (vs. SCE). The optimum conditions for the analysis of copper(II) ion include pH (5.8-7.0), 60 microgM PPKO and an accumulation potential of -0.5 V (vs. SCE). The peak current is proportional to the concentration of copper over the range 0.3-76 ng mL(-1) with a detection limit of 0.01ng mL(-1) with an accumulation time of 60 s. The speciation of different forms of complex between copper(II) ion and PPKO, using the Best (Martell program), followed pH measurement were examined. The method was applied to the determination of copper(II) ion content in real samples successfully.     

Stripping voltammetric determination of copper(II) in natural waters and human hairs based on the adsorption of its complex with Kryptofix 22 on the carbon paste electrode

Traces of copper(II) can be determined by adsorptive stripping voltammetry using Kryptofix 22 as complex forming reagent. First, copper(II)-Kryptofix 22 complex was adsorbed on the carbon paste electrode in phosphate buffer pH 5.3 with an accumulation potential of −0.5 V. Following this, the adsorbed complex was oxidized and detected by anodic differential pulse voltammetric scan from −0.2 to 0.1 V. The effective parameters of sensor response were examined. The detection limit of copper(II) was 1.1 μg/L and relative standard deviations for 50 and 150 μg/L of Cu(II) were 1.2 and 0.96%, respectively. The calibration curve was linear for 2–150 μg/L of copper(II). This technique does not use mercury and therefore is environmentally beneficial. The method, which is reasonably sensitive and selective, has been successfully applied to the determination of trace amounts of copper(II) in water and human hair samples.     

Preconcentration and Determination of Copper(II) at a Chemically Modified Electrode Containing Salicylaldehyde Thiosemicarbazone

A chemically modified electrode (CME) containing salicylaldehyde thiosemicarbazone (TSCsal) was evaluated for the ability to preconcentrate copper(II) prior to quantification by voltammetry. The CME has been used for the very sensitive and selective analysis of trace amounts of copper(II). A detection limit of 0.1 ppb was obtained by applying anodic stripping voltammetry with a flow system. The parameters that affect the sensitivity and possible interference by other ions or chelating agents have been examined in detail. The CME exhibits high stability and the response could be reproduced for four preconcentration-determination-renewal cycles [10ppbCu(II)] with a 2.87% relative standard deviation. The proposed method has been applied to the determination of copper(II) in tap water, drinking water, and NASS-3 standard reference sea water samples. The results gave satisfactory recoveries.     

单扫示波极谱法同时测定土壤中有效态铜铅镉

在ｐＨ５．４的硝酸－乙酸钠介质中，Ｃｕ＾２＋（ｐｂ＾２＋，Ｃｄ＾２＋）－７－碘－８羟基喹啉－５－磺酸－氯化四苯胂络合物产生灵敏络合吸附法，比较了五种浸提剂对不同土壤中有效态铜，铅，镉的浸提能力。在ｐＨ４．７的乙酸－乙酸钠缓冲溶液中，用巯基棉富集分离铜，铅，镉，用本法测定土壤中有效态铜，铅，镉，结果满意。     

Facile Synthesis and Characterization of 5-[(3-Methylthiophene-2-yl-methyleneamino)]-2-mercaptobenzimidazole and Its Potentiometric Sensor Application in a Polyvinyl Chloride Membrane for the Determination of Copper(II)

A novel Schiff base designated as 5-[(3-methylthiophene-2-yl-methyleneamino)]-2-mercaptobenzimidazole was synthesized and characterized. A polyvinyl chloride-membrane potentiometric copper(II)-selective sensor was prepared by using the synthesized 5-[(3-methylthiophene-2-yl-methyleneamino)]-2-mercaptobenzimidazole compound. The prepared polyvinyl chloride-membrane copper(II)-selective sensor exhibited very good selectivity and sensitive potentiometric response towards copper(II) ions compared to a wide variety of other cations. The sensor had a fast response time of <5?s, and showed a linear Nerstian behavior to copper(II) ions over a wide concentration range from 1.0?×?10^?5 to 1.0?×?10^?1 mol L^?1 with a slope of 29.2?±?0.7 and correlation coefficient of 0.9998. The prepared polyvinyl chloride-membrane copper(II)-selective sensor was used for 14 weeks without any significant change in its potentiometric response. The potentiometric response of the developed sensor was highly repeatable. Additionally, the developed sensor was used as an indicator electrode for the potentiometric titration of copper(II) ion with ethylenediaminetetraacetic acid. The sensor was also successfully applied to the direct determination of copper(II) ions in tap water, river water, and dam water samples.     

Magnetic separation of heavy metal ions and evaluation based on surface‐enhanced Raman spectroscopy: Copper(II) ions as a case study

A new approach was developed for the magnetic separation of copper(II) ions with easy operation and high efficiency. p‐Mercaptobenzoic acid served as the modified tag of Fe₂O₃@Au nanoparticles both for the chelation ligand and Raman reporter. Through the chelation between the copper(II) ions and carboxyl groups on the gold shell, the Fe₂O₃@Au nanoparticles aggregated to form networks that were enriched and separated from the solution by a magnet. A significant decrease in the concentration of copper(II) ions in the supernatant solution was observed. An extremely sensitive method based on surface‐enhanced Raman spectroscopy was employed to detect free copper(II) ions that remained after the magnetic separation, and thus to evaluate the separation efficiency. The results indicated the intensities of the surface‐enhanced Raman spectroscopy bands from p‐mercaptobenzoic acid were dependent on the concentration of copper(II) ions, and the concentration was decreased by several orders of magnitude after the magnetic separation. The present protocol effectively decreased the total amount of heavy metal ions in the solution. This approach opens a potential application in the magnetic separation and highly sensitive detection of heavy metal ions.     

Determination of copper(II) based on its catalytic effect on thiosemicarbazide-H(2)O(2)-CTMAB chemiluminescence reaction

A novel chemiluminescence (CL) reaction, thiosemicarbazide (TSC)–H₂O₂, for the determination of copper at nanogram per milliliter level in batch type is described. The method is based on the catalytic effect of copper(II) on the oxidation of TSC with hydrogen peroxide to produce light emission. The emitted light was observed by using a conventional fluorescence detector. In the optimum conditions, calibration graph was linear in the range of 0.1–1.3 ppm. The limit of detection was 10 ppb. The relative standard deviation for five determinations of 0.5 ppm copper(II) was 1.93%. The proposed method permitted the selective and sensitive determination of Cu(II) in human hair and wheat flour with sufficient precision. The possible mechanism for the new chemiluminescence reaction was also discussed.     

Gas chromatographic determination of nitric oxide at sub-ppm levels

The highly sensitive procedure involves the reaction of nitric oxide with various aromatic amines in the presence of copper (II) halide at room temperature and the gas chromatographic measurement of the aryl halide formed with an electron capture detector. The conversion yield of nitric oxide and the sensitivity of the detector to each product were studied. The system containing 3,4-dichloroaniline and copper(II) bromide is the most sensitive; the detection limit is 0.01 ppm, which indicates the possibility of determining nitric oxide in air samples without preconcentration. Gases commonly encountered in polluted air do not interfere, except for nitrogen dioxide, which can be removed by the Saltzman method.