Sample records for dimethylglyoxime

  1. Sensitivity and specificity of the nickel spot (dimethylglyoxime) test

    Thyssen, Jacob P; Skare, Lizbet; Lundgren, Lennart;


    The accuracy of the dimethylglyoxime (DMG) nickel spot test has been questioned because of false negative and positive test reactions. The EN 1811, a European standard reference method developed by the European Committee for Standardization (CEN), is fine-tuned to estimate nickel release around...... the limit value of the EU Nickel Directive from products intended to come into direct and prolonged skin contact. Because assessments according to EN 1811 are expensive to perform, time consuming, and may destruct the test item, it should be of great value to know the accuracy of the DMG screening test....

  2. Dichlorido(dimethylglyoximato-κ2N,N′(dimethylglyoxime-κ2N,N′cobalt(III

    A. Dayalan


    Full Text Available In the title compound, [Co(C4H7N2O2Cl2(C4H8N2O2], the CoIII ion has a distorted octahedral coordination environment. The equatorial plane consists of four N atoms, two each from the dimethylglyoxime and dimethylglyoximate ligands, while the two axial positions are occupied by two chloride ions. Strong intramolecular O—H...O hydrogen bonds are observed between the dimethylglyoxime and dimethylglyoximate ligands. Molecules are linked into a chain running along the [101] direction by O—H...O and C—H...Cl hydrogen bonds. The chains are cross-linked through intermolecular C—H...Cl hydrogen bonds.

  3. Evaluation of the dimethylglyoxime stick test for the detection of nickel

    Menné, T; Andersen, Klaus Ejner; Kaaber, K


    The value of the dimethylglyoxime stick test for the detection of nickel was determined for 54 randomly purchased metal objects designed for prolonged skin contact, and for 15 metal alloys of known composition. Surface nickel content was determined by EDAX analysis (energy dispersive X-ray) and n......The value of the dimethylglyoxime stick test for the detection of nickel was determined for 54 randomly purchased metal objects designed for prolonged skin contact, and for 15 metal alloys of known composition. Surface nickel content was determined by EDAX analysis (energy dispersive X......-ray) and nickel release in synthetic sweat was measured by Zeemann atomic absorption spectrometry. The study confirmed that the dimethylglyoxime stick test will identify most nickel containing alloys. There are, however, important exceptions. In such cases provocative user tests or patch tests with the suspected...

  4. Cloud point extraction, preconcentration and spectrophotometric determination of nickel in water samples using dimethylglyoxime

    Morteza Bahram


    Full Text Available A new and simple method for the preconcentration and spectrophotometric determination of trace amounts of nickel was developed by cloud point extraction (CPE. In the proposed work, dimethylglyoxime (DMG was used as the chelating agent and Triton X-114 was selected as a non-ionic surfactant for CPE. The parameters affecting the cloud point extraction including the pH of sample solution, concentration of the chelating agent and surfactant, equilibration temperature and time were optimized. Under the optimum conditions, the calibration graph was linear in the range of 10-150 ng mL-1 with a detection limit of 4 ng mL-1. The relative standard deviation for 9 replicates of 100 ng mL-1 Ni(II was 1.04%. The interference effect of some anions and cations was studied. The method was applied to the determination of Ni(II in water samples with satisfactory results.

  5. The outcome of dimethylglyoxime testing in a sample of cell phones in Denmark

    Thyssen, J.P.; Johansen, J.D.; Zachariae, C.;


    Background: Nickel dermatitis may be caused by frequent and prolonged use of cell phones. Because little is known about the frequency of nickel release from cell phones, it is difficult to estimate the risk of nickel sensitization and dermatitis among their users. Objective: Inspired by a recent...... case of nickel dermatitis from prolonged cell phone use, the frequency of dimethylglyoxime (DMG)-positive cell phones on the Danish market was investigated. Methods: Five major cell phone companies were contacted. Two were visited, and the DMG test was performed on a sample of their products. Results......: 5 of 15 (33.3%) phones from company A and 3 of 26 (11.5%) phones from company B showed at least 1 positive reaction. 3 phones had more than 1 positive DMG spots. Conclusions: This study documents that excessive nickel release (i.e. a positive DMG test) is relatively frequent in a sample of cell...

  6. A method for the determination of ascorbic acid using the iron(II)-pyridine-dimethylglyoxime complex

    Arya, S. P.; Mahajan, M. [Haryana, Kurukshetra Univ. (India). Dept. of Chemistry


    A simple and rapid spectrophotometric method for the determination of ascorbic acid is proposed. Ascorbic acid reduces iron (III) to iron (II) which forms a red colored complex with dimethylglyoxime in the presence of pyridine. The absorbance of the resulting solution is measured at 514 nm and a linear relationship between absorbance and concentration of ascorbic acid is observed up to 14 {mu}g ml{sup -1}. Studies on the interference of substances usually associated with ascorbic acid have been carried out and the applicability of the method has been tested by analysing pharmaceutical preparations of vitamin C. [Italiano] Si propone un rapido e semplice metodo spettrofotometrico per la determinazione dell`acido ascorbico. L`acido ascorbico riduce il ferro(III) a ferro(II) che forma con la dimetilgliossima, in presenza di piridina, un complesso colorato in rosso. L`assorbanza della soluzione risultante e` misurata a 514 nm e si ottiene una relazione lineare tra assorbanza e concentrazione dell`acido ascorbico fino a 14 {mu}g ml{sup -1}. Si sono condotti studi sugli interferenti usualmente associati all`acido ascorbico ed e` stata valutata l`applicabilita` del metodo all`analisi di preparati farmaceutici di vitamina C.

  7. Effective removal of Ni(II) from aqueous solutions by modification of nano particles of clinoptilolite with dimethylglyoxime.

    Nezamzadeh-Ejhieh, Alireza; Kabiri-Samani, Mehdi


    In this work an Iranian natural clinoptilolite tuff was pre-treated and changed to the micro (MCP) and nano (NCP) particles by mechanical method. Modification of micro and nano particles and also their Ni-exchanged forms were done by dimethylglyoxime (DMG). The raw and modified samples were characterized by XRD, FT-IR, SEM, BET, TG-DTG and energy dispersive analysis X-ray spectroscopy (EDAX). Removal of Ni(II) by modified and unmodified samples was investigated in batch procedure. It was found that NCP-DMG has higher capacity for removal of Ni(II). The effects of analytical parameters such as pH, dose of DMG, concentration of nickel solution, contact time and selectivity were studied and the optimal operation parameters were found as follows: pHPZC: 7.6, CNi(II): 0.01 M, contact time: 360 min and DMG dosage: 5mM. The results of selectivity experiments showed that the modified zeolite has a good selectivity for nickel in the presence of different multivalent cations. Langmuir and Freundlich isotherm models were adopted to describe the adsorption isotherms. Adsorption isotherms of Ni(II) ions could be best modelled by Langmuir equation, that indicate the monolayer sorption of Ni(II). Comparison of two kinetic models indicates that the adsorption kinetic can be well described by the pseudo-second-order rate equation that indicates that the rate limiting step for the process involves chemical reaction. The negative ΔH and ΔG indicate an exothermic and spontaneously process. The negative ΔS indicates that the adsorption of nickel cations from solution occurs with lower amount ion replacement, thus chemisorptions due to complex formation are dominant process in nickel removal.

  8. Synthesis, spectroscopy, crystal structure and DFT studies of cobalt(III) complexes featuring dimethylglyoximate and aniline or p-bromoaniline ligands

    Berradj, O.; Adkhis, A.; Bougherra, H.; Bruno, G.; Michaud, F.


    Two new cobalt(III) compounds [Co(Hdmg)2(Ani)2]NO3·2H2O (I) and [Co(Hdmg)2(Ani-Br)2]NO3·H2O (II), where Hdmg is the dimethylglyoximate monoanion, Ani is aniline and Ani-Br is p-bromoaniline, were synthesized and characterized using spectroscopic techniques including IR, UV-Visible, and X-ray diffraction. In the octahedral Co(III) complexes, the two dimethylglyoximato ions are coordinated to a cobalt atom in a planar configuration and are connected by intramolecular Osbnd H⋯O hydrogen-bonding. The nitrogen atoms of the two aniline ligands occupy the apical sites. A Density Functional Theory approach has been successfully used for the investigation of the nature of solid state interactions and determination of the whole molecular packing. It was found that the computational data are in good agreement with the experimental results.

  9. 丁二酮肟比色法测定包膜尿素释放养分速率%Determination of controlled release rate of membrane coated fertilizer by colorimetry with dimethylglyoxime

    戴小敏; 刘袖洞; 左秀锦; 马小军


    以改性淀粉包膜尿素为模型,探讨用丁二酮肟比色法测定包膜尿素释放养分速率,以达到快速评价包膜尿素控制释放性能的目的.结果表明,丁二酮肟比色法测定包膜尿素释放养分速率可行,自制改性淀粉包膜尿素具有一定的控制释放性能.%Membrane coated Uurea was prepared with modified starch, and colorimetry with dimethylglyoxime was used to investigate the controlled release rate of urea. The purpose was to provide a fast analytical method to evaluate the controlled release property of membrane coated urea. The results showed that colorimetry with dimethylglyoxime was feasible to analyze release rate of urea.

  10. 丁二酮肟重量法测定双乙腈二氯化钯中钯的含量%Determination of palladium Content in Bis (acetonitrile) Palladium (Ⅱ)Chloride by Dimethylglyoxime Gravimetry Method



    试样经盐酸-硝酸混合酸溶解,高氯酸冒烟,于盐酸体系中用丁二酮肟沉淀剂与溶液中的钯络合,形成沉淀,计算样品双乙腈二氯化钯中钯的质量分数。对样品的预处理和检测方法进行了研究和对比。试验证明,本方法准确、简便、有效,适用于双乙腈二氯化钯中钯含量的检测。%The analytic method of determining the content of palladium content by dimethylglyoxime gravimetry method in 5%(v/v) hydrochloric acid was used, with hydrochloric acid, nitric acid-perchloric acid melting, bis(acetonitrile)palladium(Ⅱ)chloride in the electric heating plate. The concentration of palladium content in solution was deposited by dimethylglyoxime gravimetry in order to calculate the sample mass fraction of palladium in bis(acetonitrile)palladium(Ⅱ)chloride. The methods for sample pretreatment and determination were studied and contrasted. The experiment proved that the accuracy of this method, this method is convenient and rapid, especially suitable for determining the content of palladium in bis(acetonitrile)palladium(Ⅱ)chloride.

  11. Preparation and Spectral Properties of Mixed-Ligand Complexes of VO(IV, Ni(II, Zn(II, Pd(II, Cd(II and Pb(II with Dimethylglyoxime and N-acetylglycine

    Shayma A. Shaker


    Full Text Available A number of mixed-ligand complexes of the general formula [M(D(G] where D=dimethylglyoximato monoanion, G=N-acetylglycinato and M=VO(IV, Ni(II, Zn(II, Pd(II, Cd(II and Pb(II were prepared. Each complex was characterized by elemental analysis, determination of metal, infrared spectra, electronic spectra, (1H and 13C NMR spectra, conductivity and magnetic moments. All these complexes were not soluble in some of the organic solvent but highly soluble in dimethylformamide. The conductivity data showed the non-electrolytic nature of the complexes. The electronic spectra exhibited absorption bands in the visible region caused by the d-d electronic transition such as VO(IV, Ni(II and Pd(II. The IR and (1H, 13C NMR spectra which have indicate that the dimethylglyoxime was coordinated with the metal ions through the N and O atoms of the oxime group and N-acetylglycine was coordinated with metal ions through the N atom and terminal carboxyl oxygen atom.

  12. Sensitivity and specificity of the nickel spot (dimethylglyoxime) test

    Thyssen, Jacob P; Skare, Lizbet; Lundgren, Lennart


    the limit value of the EU Nickel Directive from products intended to come into direct and prolonged skin contact. Because assessments according to EN 1811 are expensive to perform, time consuming, and may destruct the test item, it should be of great value to know the accuracy of the DMG screening test....

  13. Optimal synthesis of a Ni(II)-dimethylglyoxime ion-imprinted polymer ...

    2Department of Chemistry, Rhodes University, PO Box 94, Grahamstown 6140, South Africa ... soil and mine tailing samples showed that the uniform design experimental method is effective and efficient for .... DMG IIPs were prepared through the process described but ..... Analysis of BCR-142R certified reference material.

  14. Incorporation of Ni(II)-dimethylglyoxime ion-imprinted polymer into ...


    Feb 3, 2011 ... Scanning electron microscopy images were acquired by a. TS5136ML Digital ... Series inductively coupled plasma-optical emission spectrometer .... 50 mg of multi-wall carbon nanotubes (which are also nanoma- terials) as ...

  15. Synthesis, Physico-Chemical and Antimicrobial Properties of Co(II, Ni(II, and Cu(II Mixed-Ligand Complexes of Dimethylglyoxime

    A.A. Osunlaja


    Full Text Available The synthesis of non-electrolyte mixed-ligand complexes of the general formula [M(HdmgB], where M = Co(II, Ni(II or Cu(II Hdmg = dimethylglyoximato monoanion, B = 2- aminophenol(2-aph, diethylamine (dea or malonic acid (MOH are described. Metal analysis, melting points, solubility, conductivity, IR and UV/Visible electronic spectra were used in determining their physico-chemical properties. The antimicrobial activities of the complexes were tested against Esherichia coli, Staphylococcus aureus, Aspergillus niger and Aspergillus flavus. The complexes melted/decomposed at 120-306ºC and, most of them dissolved only in polar solvents. The colours of the complexes are mostly dark - brown or red. The spectral results suggest the binding of Hdmg, 2-amino phenol or malonic acid through the N atom and O atoms respectively to the metal ion In the electronic spectra of the complexes, the absorption bands observed in the UV/Visible region are presumed to be either due to charge transfer or intra-ligand transitions from the ligands or d-d transitions from the metal ions. The complexes showed marked antimicrobial activity against the tested microbes at 10 mg/mL. The possible use of the complexes as chemotherapeutic agents is hereby suggested.

  16. 丁二酮肟分离-EDTA络合返滴定法测定哈氏合金中的镍%Determination of nickel in hastelloy alloy by dimethylglyoxime separation-EDTA complex back titration

    许洁瑜; 麦丽碧; 陈晓东



  17. Chemical modifiers in electrothermal atomic absorption determination of Platinum and Palladium containing preparations in blood serum

    Аntonina Alemasova


    Full Text Available The biological liquids matrixes influence on the characteristic masses and repeatability of Pt and Pd electrothermal atomic absorption spectroscopy (ETAAS determination was studied. The chemical modifiers dimethylglyoxime and ascorbic acid for matrix interferences elimination and ETAAS results repeatability improvement were proposed while bioliquids ETAAS analysis, and their action mechanism was discussed.

  18. Periumbilical allergic contact dermatitis: blue jeans or belt buckles?

    Byer, Tara T; Morrell, Dean S


    Nickel is the most ubiquitous contact allergen among children and adolescents. Metal blue jeans buttons and belts have been noted to cause nickel dermatitis around the umbilicus. For these children, traditional teaching is strict avoidance of all pants with metal snaps/buttons, particularly blue jeans. In this study we tested 90 pairs of blue jeans and 47 belts for nickel using the dimethylglyoxime spot test. Only 10% of blue jeans tested positive, while 53% of belts tested positive. Furthermore, 10 pairs of nickel-negative blue jeans remained negative after 10 washings. Overall we found no resistance to testing in clothing stores. From these results, we recommend that patients with allergic contact dermatitis secondary to nickel need not strictly avoid blue jeans and metal belt buckles. Rather, families should be encouraged to use the dimethylglyoxime spot test to test these items for nickel prior to purchase.

  19. Evidences of Cold-Melting Mechanism and Cold-Dissolving-Melting Mechanism for Low-heating Solid-state Reaction%低热固相反应冷融熔机理和冷溶熔机理的证据

    唐新村; 黄伯云; 贺跃辉


    The cold-melting mechanism and the cold-dissolving-melting mechanism were further studied by TG/DTA and in situ micro-photographs techniques with the mixture of dimethylglyoxime and Ni(Ac)2·4H2O, and the mixture of dimethylglyoxime and anhydrous Ni(Ac)2 as the modeled reactive examples. The endothermic peaks on the DTA curves at about 38℃ revealed the formation process of the cold-melting layer and cold-dissolving-melting layer on the surface of reactant particles. Further, the cold-melting state and the cold-dissolving-melting state were observed by the micrographs. These results provided the direct evidences for the theories of cold-melting mechanism and the cold-dissolving-melting mechanism.

  20. Hydrometallurgical recovery of metal values from sulfuric acid leaching liquor of spent lithium-ion batteries.

    Chen, Xiangping; Chen, Yongbin; Zhou, Tao; Liu, Depei; Hu, Hang; Fan, Shaoyun


    Environmentally hazardous substances contained in spent Li-ion batteries, such as heavy metals and nocuous organics, will pose a threat to the environment and human health. On the other hand, the sustainable recycling of spent lithium-ion batteries may bring about environmental and economic benefits. In this study, a hydrometallurgical process was adopted for the comprehensive recovery of nickel, manganese, cobalt and lithium from sulfuric acid leaching liquor from waste cathode materials of spent lithium-ion batteries. First, nickel ions were selectively precipitated and recovered using dimethylglyoxime reagent. Recycled dimethylglyoxime could be re-used as precipitant for nickel and revealed similar precipitation performance compared with fresh dimethylglyoxime. Then the separation of manganese and cobalt was conducted by solvent extraction method using cobalt loaded D2EHPA. And McCabe-Thiele isotherm was employed for the prediction of the degree of separation and the number of extraction stages needed at specific experimental conditions. Finally, cobalt and lithium were sequentially precipitated and recovered as CoC2O4 ⋅ 2H2O and Li2CO3 using ammonium oxalate solution and saturated sodium carbonate solution, respectively. Recovery efficiencies could be attained as follows: 98.7% for Ni; 97.1% for Mn, 98.2% for Co and 81.0% for Li under optimized experimental conditions. This hydrometallurgical process may promise a candidate for the effective separation and recovery of metal values from the sulfuric acid leaching liquor.

  1. Determination of 63Ni and 59Ni in spent ion-exchange resin and activated charcoal from the IEA-R1 nuclear research reactor.

    Taddei, M H T; Macacini, J F; Vicente, R; Marumo, J T; Sakata, S K; Terremoto, L A A


    A radiochemical method has been adapted to determine (59)Ni and (63)Ni in samples of radioactive wastes from the water cleanup system of the IEA-R1 nuclear research reactor. The process includes extraction chromatographic resin with dimethylglyoxime (DMG) as a functional group. Activity concentrations of (59)Ni and (63)Ni were measured, respectively, by X-ray spectrometry and liquid scintillation counting, whereas the chemical yield was determined by ICP-OES. The average ratio of measured activity concentrations of (63)Ni and (59)Ni agree well with theory. Copyright © 2013 Elsevier Ltd. All rights reserved.


    Leandra de Oliveira Cruz da Silva


    Full Text Available The adsorptive stripping voltammetry with differential pulse cathodic through the use of a mixture of complexing agents dimethylglyoxime and oxine was used for an exploratory study simultaneously of ions cadmium, cobalt, copper, nickel, lead and zinc. Were obtained voltammograms of the 64 individual solutions used in planning and current data were submitted to principal component analysis (PCA, allowing to characterize the trends of the solutions of metal ions studied. The system can be described in eight principal components that explained 98.32% of variance. Since the first three principal components accumulated approximately 85.46% of the total variance.

  3. Highly selective micro-sequential injection lab-on-valve (μSI-LOV) method for determination of ultra trace concentrations of nickel in saline matrices using detection by electrothermal atomic absorption spectrometr

    Long, Xiangbao; Miró, Manuel; Jensen, Rikard


    A highly selective procedure is proposed for the determination of ultra trace level concentrations of nickel in saline aqueous matrices exploiting a micro sequential injection lab-on-salve (μSI-LOV) sample pretreatment protocol comprising bead injection separation/pre-concentration and detection...... by electrothermal atomic absorption spectrometry (ETAAS). Based on the dimethylglyoxime (DMG) gravimetric procedure used for nickel analysis, the sample, as contained in pH 9.0 buffer, is, after on-line merging with the chelating reagent, transported to a reaction coil attached to one of the external ports...

  4. Density Functional Theory and Car-Parrinello Molecular Dynamics Study of the Hydrogen-Producing Mechanism of the Co(dmgBF2)2 and Co(dmgH)2 Cobaloxime Complexes in Acetonitrile-Water Solvent.

    Chen, Jinfan; Sit, Patrick H-L


    The catalytic hydrogen-producing processes of two prototypical cobaloxime catalysts, Co(dmgBF2)2 (dmgBF2 = difluoroboryl-dimethylglyoxime) and Co(dmgH)2 (dmgH = dimethylglyoxime), were studied by density functional theory (DFT) and Car-Parrinello molecular dynamics (CPMD) simulations in the explicit acetonitrile-water solvent. Our study demonstrates the key role of water molecules as shuttles to deliver protons to the cobalt active centers of these catalysts. However, the transfer of protons to the cobalt centers also competes with the diffusion of the proton away from the complex via the hydrogen bond network of water. Protons were found to react with the oxygen of the side group of Co(dmgH)2, while a similar reaction was not observed for Co(dmgBF2)2. This explains the experimentally observed relative instability of Co(dmgH)2 in the acidic medium. The rate-limiting step of the hydrogen-producing process was found to be the first proton transfer to the cobalt center for both cobaloxime complexes. Structural and electron population analysis was carried out to provide insight into the origin of the difference of the proton transfer free-energy barriers of these two cobalt complexes. Our study has contributed to the key microscopic understanding of the hydrogen-producing process by this class of catalysts.

  5. Determination of Trace Nickel in Copper Alloy by Inductively Coupled Spectrophotometry%萃取分离-分光光度法测定铜合金中痕量镍



    用硝酸溶解试样,在pH 6.0~7.0范围内,用三氯甲烷萃取丁二酮肟镍与铜基体分离。以盐酸反萃取镍。在碱性介质中,氧化剂存在下,镍与丁二酮肟形成络合物,在波长480nm处测定吸光度。0.2~2μg·mL-1范围内符合朗伯-比尔定律,回收率达100.7%,所测镍量范围为0.001%~0.010%。%Using nitric acid to dissolve the sample, pH was 6.0~7.0, dimethylglyoxime-nickel was separated from copper matrix by chloroform extraction. Hydrochloric acid was used to extract nickel. In alkaline medium, at the presence of oxidizing agent, nickel and dimethylglyoxime formed complex, the absorbance was measured at the wavelength of 480nm. In range of 0.2μg/mL~2μg/mL, the absorbance was accorded with Lambert-Beer’s law, the recovery was 100.7%, the nickel content range was 0.001%~0.010%.

  6. 丁二酮肟光度法测定红土镍矿中的镍%Determination of Nickel Content in Laterite Nickel Ores by Dimetylglyoxime Spectrophotometry

    李波; 孙宝莲; 周恺; 褚宁; 蒋晓光; 杨平平; 禄妮


    提出了红土镍矿中镍量的酸溶-丁二酮肟分光光度测定法.试样经混酸(盐酸+硝酸+氢氟酸)溶解,高氯酸冒烟.在氢 氧化钠介质中,以过硫酸铵作氧化剂,使镍与丁二酮肟生成可溶性的酒红色络合物,于460 nm波长处进行镍的光度法测定.将该法应用于含镍量不同的9个红土镍矿样品中镍的测定,相对误差(RSD)为1.10%~3.78% (n=11),加标回收率在98.5%~101.5%之间,与其他3个实验室测定结果以及不同分析方法(过氧化钠碱熔-丁二酮肟光度法、AAS法和ICP-AES法)的测定结果一致.%Nickel content in laterite nickel ores was determined by acid digestion-dimethylglyoxime photometric method. Samples were dissolved with mixed acid of HCl-HNO3-HF, and then made through perchloric acid smoke. In sodium hydroxide medium, with ammonium persulfate as oxidant, a soluble wine-red complex was formed through the reaction of nickel and dimethylglyoxime. Nickel content was determined at 460 nm wavelength. The proposed method was applied to determine the nickel content in 9 samples of different laterite nickel ores. The relative deviation (RSD) was between 1.10%~3.78%, and the recovery was in the range of 98.5%~101.5%. Compared with that of other three laboratories and three different methods including sodium peroxide fusion-dimethylglyoxime spectrophotometry, AAS and ICP-AES, the results were consistent.

  7. Nickel and Cobalt Release From Children's Toys Purchased in Denmark and the United States

    Jensen, P.; Hamann, Dathan; Hamann, Carsten R.


    to identify new sources of nickel exposure in this age group is important. Recent case reports have described allergic nickel contact dermatitis in children following exposure to toys, but the magnitude of this problem is unknown. Objective : The aim of this study was to evaluate nickel and cobalt release...... from children's toys. Methods : We purchased 212 toys in 18 different retail and online stores in the United States and Denmark. Nickel and cobalt release was tested using the dimethylglyoxime and cobalt screening spot tests. Results : A total of 73 toys (34.4%) released nickel, and none released...... cobalt. Conclusions : Toys are a commonly overlooked source of nickel exposure and sensitization. Therefore, dermatologists, allergists, and pediatricians should consider the role of toys in their evaluation of children with dermatitis, and the parents of children with positive nickel patch test...

  8. Pyrolyzed Photoresist Carbon Electrodes for Trace Electroanalysis of Nickel(II

    Ligia Maria Moretto


    Full Text Available Novel pyrolyzed photoresist carbon electrodes for electroanalytical applications have been produced by photolithographic technology followed by pyrolysis of the photoresist. A study of the determination of Ni(II dimethylglyoximate (Ni-DMG through adsorptive cathodic stripping voltammetry at an in situ bismuth-modified pyrolyzed photoresist electrode (Bi-PPCE is reported. The experimental conditions for the deposition of a bismuth film on the PPCE were optimized. The Bi-PPCE allowed the analysis of trace concentrations of Ni(II, even in the presence of Co(II, which is the main interference in this analysis, with cathodic stripping square wave voltammograms characterized by well-separated stripping peaks. The calculated limits of detection (LOD were 20 ng∙L−1 for Ni(II alone and 500 ng∙L−1 in the presence of Co(II. The optimized method was finally applied to the analysis of certified spring water (NIST1640a.

  9. Synthesis and Characterization of Mixed Iron-Manganese Oxide Nanoparticles and Their Application for Efficient Nickel Ion Removal from Aqueous Samples

    Serra, Antonio; Monteduro, Anna Grazia; Padmanabhan, Sanosh Kunjalukkal; Licciulli, Antonio; Bonfrate, Valentina; Salvatore, Luca; Calcagnile, Lucio


    Mixed iron-manganese oxide nanoparticles, synthesized by a simple procedure, were used to remove nickel ion from aqueous solutions. Nanostructures, prepared by using different weight percents of manganese, were characterized by transmission electron microscopy, selected area diffraction, X-ray diffraction, Raman spectroscopy, and vibrating sample magnetometry. Adsorption/desorption isotherm curves demonstrated that manganese inclusions enhance the specific surface area three times and the pores volume ten times. This feature was crucial to decontaminate both aqueous samples and food extracts from nickel ion. Efficient removal of Ni2+ was highlighted by the well-known dimethylglyoxime test and by ICP-MS analysis and the possibility of regenerating the nanostructure was obtained by a washing treatment in disodium ethylenediaminetetraacetate solution. PMID:28804670

  10. The potential use of indigenous nickel hyperaccumulators for small-scale mining in The Philippines

    E.S. Fernando


    Full Text Available Uptake of nickel and three other heavy metals (copper, cobalt, and chromium was examined in 33 species of the common and rare native vascular plants growing in an ultramafic area currently subjected to mining in Zambales Province, Luzon, Philippines. Leaf tissue samples were initially screened in the field using filter paper impregnated with dimethylglyoxime (1% solution in 70% ethyl alcohol and later analyzed by atomic absorption spectroscopy. One species was found to be a hypernickelophore (>10,000 µg/g, eight species were nickel hyperaccumulators (>1,000 µg/g, nineteen species were hemi-accumulators (>100-1,000 µg/g, and five species were non-accumulators (<100 µg/g. This paper significantly adds to the list of hyperaccumulator species first reported for the Philippines in 1992. The findings will be discussed in context of using indigenous species for post mining ecological restoration and nickel phytoextraction in small-scale mining in the Philippines


    Eduard Coropceanu


    Full Text Available It was elaborated the methodology of synthesizing a series of new dioximates of Co(III with the general formula [Co(DioxH2(L2]X⋅nH2O, where DioxH – the dioxime anione: dimethylglyoxime (DH2, 1,2-cyclohexanedionedioxime (NioxH2; L - thiocarbamide (Thio, pyridine (Py, aniline (An, sulphanilamide (Sam;X - [BF4]-, [ZrF6]2-, [TiF6]2-, whose structures have been studied with the help of contemporary physical methods: spectroscopy IR, UV-Vis, RMN 1H, 19F, X-ray analysis. There were elaborated optimal conditions of using cobalt dioximates with fluorine in order to intensify the biosynthesis of amylases and lipases by Aspergillus and Rhizopus strains, respectively. The tested compounds increase the lipolytic activity of Rhizopus arrhisus micromycetes.

  12. Nickel release from inexpensive jewelry and hair clasps purchased in an EU country - Are consumers sufficiently protected from nickel exposure?

    Thyssen, Jacob Pontoppidan; Menné, Torkil; Johansen, Jeanne Duus


    BACKGROUND: Nickel allergic subjects are at risk factor of acquiring hand eczema. In 1990 and 1994, respectively, Denmark and member states in the EU regulated nickel release from selected consumer products. The intention was that the nickel epidemic could be controlled and prevented if the general...... population was protected from high cutaneous nickel concentrations. Despite a decrease, the prevalence of nickel allergy remains high as nearly 10% of young women are nickel allergic. OBJECTIVE: This study aimed to perform dimethylglyoxime (DMG) testing of inexpensive jewelry and hair clasps purchased from...... random stores in Copenhagen, Denmark to detect the proportion of items that may result in nickel allergy. METHODS: Inexpensive jewelry and hair clasps were purchased from 36 stores and street vendors in Copenhagen and were later tested for nickel release using the DMG test. RESULTS: The study showed...

  13. Assessment of nickel and cobalt release from 200 unused hand-held work tools for sale in Denmark — Sources of occupational metal contact dermatitis?

    Thyssen, Jacob P.; Jensen, Peter; Lidén, Carola


    tools for sale in 2 retailers of home improvement and construction products were analyzed qualitatively for metal release using the colorimetric nickel and cobalt spot tests. ResultsNickel release was identified from 5% of 200 work tools using the dimethylglyoxime (DMG) test. In 8 of 10, positive......IntroductionNickel and cobalt allergy remain frequent in dermatitis patients. It is important to determine possible nickel and cobalt exposures at work as these may offer important information to regulators and physicians who perform patch testing. Clinical relevance of metal exposure is usually...... assessed by the treating physician via the medical history and by presentation of allergic contact dermatitis. ObjectivesTo screen unused non-powered hand-held work tools for nickel and cobalt release by using colorimetric spot tests. Materials & methodsA random selection of 200 non-powered hand-held work...

  14. Nickel allergy in patch-tested female hairdressers and assessment of nickel release from hairdressers' scissors and crochet hooks

    Thyssen, Jacob Pontoppidan; Milting, Kristina; Bregnhøj, Anne;


    BACKGROUND: Hand eczema as well as nickel contact allergy is prevalent among hairdressers. Recently, two female hairdressers were diagnosed with nickel contact allergy-related hand eczema following prolonged skin contact with scissors and crochet hooks used during work. OBJECTIVES: To determine...... the proportion of hairdressers' scissors and crochet hooks that released an excessive amount of nickel and to determine the prevalence of nickel allergy among patch-tested female hairdressers. MATERIALS: Random hairdressers' stores in Copenhagen were visited. The dimethylglyoxime (DMG) test was used to assess...... excessive nickel release. The prevalence of nickel allergy among female hairdressers from the database at Gentofte Hospital was compared with the prevalence of nickel allergy among other consecutively patch-tested dermatitis patients. RESULTS: DMG testing showed that 1 (0.5%; 95% CI = 0 - 2.0) of 200 pairs...

  15. Complexation-Based Detection of Nickel(II at a Graphene-Chelate Probe in the Presence of Cobalt and Zinc by Adsorptive Stripping Voltammetry

    Keagan Pokpas


    Full Text Available The adsorptive stripping voltammetric detection of nickel and cobalt in water samples at metal film electrodes has been extensively studied. In this work, a novel, environmentally friendly, metal-free electrochemical probe was constructed for the ultra-trace determination of Ni2+ in water samples by Adsorptive Cathodic Stripping Voltammetry (AdCSV. The electrochemical platform is based on the adsorptive accumulation of Ni2+ ions directly onto a glassy carbon electrode (GCE modified with dimethylglyoxime (DMG as chelating agent and a Nafion-graphene (NGr nanocomposite to enhance electrode sensitivity. The nafion-graphene dimethylglyoxime modified glassy carbon electrode (NGr-DMG-GCE shows superior detection capabilities as a result of the improved surface-area-to-volume ratio and enhanced electron transfer kinetics following the incorporation of single layer graphene, while limiting the toxic effects of the sensor by removal of the more common mercury, bismuth and lead films. Furthermore, for the first time the NGr-DMG-GCE, in the presence of common interfering metal ions of Co2+ and Zn2+ demonstrates good selectivity and preferential binding towards the detection of Ni2+ in water samples. Structural and morphological characterisation of the synthesised single layer graphene sheets was conducted by Raman spectrometry, HRTEM and HRSEM analysis. The instrumental parameters associated with the electrochemical response, including accumulation potential and accumulation time were investigated and optimised in addition to the influence of DMG and graphene concentrations. The NGr-DMG-GCE demonstrated well resolved, reproducible peaks, with RSD (% below 5% and a detection limit of 1.5 µg L−1 for Ni2+ reduction at an accumulation time of 120 s., the prepared electrochemical sensor exhibited good detection and quantitation towards Ni2+ detection in tap water samples, well below 0.1 mg L−1 set by the WHO and EPA standards. This comparable to the South

  16. Complexation-Based Detection of Nickel(II) at a Graphene-Chelate Probe in the Presence of Cobalt and Zinc by Adsorptive Stripping Voltammetry.

    Pokpas, Keagan; Jahed, Nazeem; Baker, Priscilla G; Iwuoha, Emmanuel I


    The adsorptive stripping voltammetric detection of nickel and cobalt in water samples at metal film electrodes has been extensively studied. In this work, a novel, environmentally friendly, metal-free electrochemical probe was constructed for the ultra-trace determination of Ni(2+) in water samples by Adsorptive Cathodic Stripping Voltammetry (AdCSV). The electrochemical platform is based on the adsorptive accumulation of Ni(2+) ions directly onto a glassy carbon electrode (GCE) modified with dimethylglyoxime (DMG) as chelating agent and a Nafion-graphene (NGr) nanocomposite to enhance electrode sensitivity. The nafion-graphene dimethylglyoxime modified glassy carbon electrode (NGr-DMG-GCE) shows superior detection capabilities as a result of the improved surface-area-to-volume ratio and enhanced electron transfer kinetics following the incorporation of single layer graphene, while limiting the toxic effects of the sensor by removal of the more common mercury, bismuth and lead films. Furthermore, for the first time the NGr-DMG-GCE, in the presence of common interfering metal ions of Co(2+) and Zn(2+) demonstrates good selectivity and preferential binding towards the detection of Ni(2+) in water samples. Structural and morphological characterisation of the synthesised single layer graphene sheets was conducted by Raman spectrometry, HRTEM and HRSEM analysis. The instrumental parameters associated with the electrochemical response, including accumulation potential and accumulation time were investigated and optimised in addition to the influence of DMG and graphene concentrations. The NGr-DMG-GCE demonstrated well resolved, reproducible peaks, with RSD (%) below 5% and a detection limit of 1.5 µg L(-1) for Ni(2+) reduction at an accumulation time of 120 s., the prepared electrochemical sensor exhibited good detection and quantitation towards Ni(2+) detection in tap water samples, well below 0.1 mg L(-1) set by the WHO and EPA standards. This comparable to the South

  17. Apparatus and technique for multiple tests by the confined-spot method of colorimetric analysis: Application to field estimation of nickel and copper

    McCarthy, J.H.; Stevens, R.E.


    The confined-spot method of colorimetric analysis is generally applicable to the semiquantitative estimation of traces of ions in solution that form colored precipitates or otherwise alter material on a confined area of reagent paper. For precise results, the rate of flow of test solutions through the reagent paper must be reproduced on successive runs, so that the same proportion of reaction products is collected each time on the confined spot. A simple apparatus gives a controlled rate of flow and makes possible the analysis of many samples at one time with good reproducibility. This apparatus utilizes the increasing pull, resulting from the gradual lowering of the water level in a tank, to draw a sample solution through a confined area of reagent paper at a reproducible rate. Application to the rapid determination of nickel with dimethylglyoxime and of copper with rubeanic acid provides a method for determination of as little as 0.06 ?? of nickel and 0.03 ?? of copper. The coefficients of variation are 14 and 22%, respectively. This method has wide applicability in more rapid and convenient determination of trace amounts of many metals.

  18. Nickel release from nickel-plated metals and stainless steels.

    Haudrechy, P; Foussereau, J; Mantout, B; Baroux, B


    Nickel release from nickel-plated metals often induces allergic contact dermatitis, but, for nickel-containing stainless steels, the effect is not well-known. In this paper, AISI 304, 316L, 303 and 430 type stainless steels, nickel and nickel-plated materials were investigated. 4 tests were performed: patch tests, leaching experiments, dimethylglyoxime (DMG) spot tests and electrochemical tests. Patch tests showed that 96% of the patients were intolerant to Ni-plated samples, and 14% to a high-sulfur stainless steel (303), while nickel-containing stainless steels with a low sulfur content elicited no reactions. Leaching experiments confirmed the patch tests: in acidic artificial sweat, Ni-plated samples released about 100 micrograms/cm2/week of nickel, while low-sulfur stainless steels released less than 0.03 microgram/cm2/week of nickel, and AISI 303 about 1.5 micrograms/cm2/week. Attention is drawn to the irrelevance of the DMG spot test, which reveals Ni present in the metal bulk but not its dissolution rate. Electrochemical experiments showed that 304 and 316 grades remain passive in the environments tested, while Ni-plated steels and AISI 303 can suffer significant cation dissolution. Thus, Ni-containing 304 and 316 steels should not induce contact dermatitis, while 303 should be avoided. A reliable nitric acid spot test is proposed to distinguish this grade from other stainless steels.

  19. Hydrometallurgical process for the recovery of metal values from spent lithium-ion batteries in citric acid media.

    Chen, Xiangping; Zhou, Tao


    In this paper, a hydrometallurgical process has been proposed to recover valuable metals from spent lithium-ion batteries in citric acid media. Leaching efficiencies as high as 97%, 95%, 94%, and 99% of Ni, Co, Mn, and Li were achieved under the optimal leaching experimental conditions of citric acid concentration of 2 mol L(-1), leaching temperature of 80 °C, leaching time of 90 min, liquid-solid ratio of 30 ml g(-1), and 2 vol. % H2O2. For the metals recovery process, nickel and cobalt were selectively precipitated by dimethylglyoxime reagent and ammonium oxalate sequentially. Then manganese was extracted by Na-D2EHPA and the manganese-loaded D2EHPA was stripped with sulfuric acid. The manganese was recovered as MnSO4 in aqueous phase and D2EHPA could be reused after saponification. Finally, lithium was precipitated by 0.5 mol L(-1) sodium phosphate. Under their optimal conditions, the recovery percentages of Ni, Co, Mn, and Li can reach 98%, 97%, 98%, and 89%, respectively. This is a relatively simple route in which all metal values could be effectively leached and recovered in citric acid media.

  20. Investigation of iron(III) reduction and trace metal interferences in the determination of dissolved iron in seawater using flow injection with luminol chemiluminescence detection

    Ussher, Simon J. [School of Earth, Ocean and Environmental Sciences (SEOES), University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom); Milne, Angela [School of Earth, Ocean and Environmental Sciences (SEOES), University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom); Department of Oceanography, Florida State University, Tallahassee, FL 32306-4320 (United States); Landing, William M. [Department of Oceanography, Florida State University, Tallahassee, FL 32306-4320 (United States); Attiq-ur-Rehman, Kakar [Department of Chemistry, University of Balochistan, Quetta (Pakistan); Seguret, Marie J.M.; Holland, Toby [School of Earth, Ocean and Environmental Sciences (SEOES), University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom); Achterberg, Eric P. [National Oceanography Centre, University of Southampton, European Way, Southampton SO14 3ZH (United Kingdom); Nabi, Abdul [Department of Chemistry, University of Balochistan, Quetta (Pakistan); Worsfold, Paul J., E-mail: [School of Earth, Ocean and Environmental Sciences (SEOES), University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom)


    A detailed investigation into the performance of two flow injection-chemiluminescence (FI-CL) manifolds (with and without a preconcentration column) for the determination of sub-nanomolar dissolved iron (Fe(II) + Fe(III)), following the reduction of Fe(III) by sulphite, in seawater is described. Kinetic experiments were conducted to examine the efficiency of reduction of inorganic Fe(III) with sulphite under different conditions and a rigorous study of the potential interference caused by other transition metals present in seawater was conducted. Using 100 {mu}M concentrations of sulphite a reduction time of 4 h was sufficient to quantitatively reduce Fe(III) in seawater. Under optimal conditions, cobalt(II) and vanadium(IV)/(III) were the major positive interferences and strategies for their removal are reported. Specifically, cobalt(II) was masked by the addition of dimethylglyoxime to the luminol solution and vanadium(IV) was removed by passing the sample through an 8-hydroxyquinoline column in a low pH carrier stream. Manganese(II) also interfered by suppression of the CL response but this was not significant at typical open ocean concentrations.

  1. Porous bimetallic PdNi catalyst with high electrocatalytic activity for ethanol electrooxidation.

    Feng, Yue; Bin, Duan; Yan, Bo; Du, Yukou; Majima, Tetsuro; Zhou, Weiqiang


    Porous bimetallic PdNi catalysts were fabricated by a novel method, namely, reduction of Pd and Ni oxides prepared via calcining the complex chelate of PdNi-dimethylglyoxime (PdNi-dmg). The morphology and composition of the as-prepared PdNi were investigated by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). Furthermore, the electrochemical properties of PdNi catalysts towards ethanol electrooxidation were also studied by electrochemical impedance spectrometry (EIS), cyclic voltammetry (CV) and chronoamperometry (CA) measurement. In comparison with porous Pd and commercial Pd/C catalysts, porous structural PdNi catalysts showed higher electrocatalytic activity and durability for ethanol electrooxidation, which may be ascribed to Pd and Ni property, large electroactive surface area and high electron transfer property. The Ni exist in the catalyst in the form of the nickel hydroxides (Ni(OH)2 and NiOOH) which have a high electron and proton conductivity enhances the catalytic activity of the catalysts. All results highlight the great potential application of the calcination-reduction method for synthesizing high active porous PdNi catalysts in direct ethanol fuel cells.

  2. Fabrication of Nitrogen-Doped Mesoporous-Carbon-Coated Palladium Nanoparticles: An Intriguing Electrocatalyst for Methanol and Formic Acid Oxidation.

    Ray, Chaiti; Dutta, Soumen; Sahoo, Ramkrishna; Roy, Anindita; Negishi, Yuichi; Pal, Tarasankar


    Inspired by the attractive catalytic properties of palladium and the inert nature of carbon supports in catalysis, a concise and simple methodology for in situ nitrogen-doped mesoporous-carbon-supported palladium nanoparticles (Pd/N-C) has been developed by carbonizing a palladium dimethylglyoximate complex. The as-synthesized Pd/N-C has been exfoliated as a fuel cell catalyst by studying the electro-oxidation of methanol and formic acid. The material synthesized at 400 °C,namely, Pd/N-C-400,exhibitssuperior mass activity and stability among catalysts synthesized under different carbonization temperaturesbetween300 and 500 °C. The unique 1D porous structure in Pd/N-C-400 helps better electron transport at the electrode surface, which eventually leads to about five times better catalytic activity and about two times higher stability than that of commercial Pd/C. Thus, our designed sacrificial metal-organic templatedirected pathway becomes a promising technique for Pd/N-C synthesis with superior catalytic performances. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Geochemical field method for determination of nickel in plants

    Reichen, L.E.


    The use of biogeochemical data in prospecting for nickel emphasizes the need for a simple, moderately accurate field method for the determination of nickel in plants. In order to follow leads provided by plants of unusual nickel content without loss of time, the plants should be analyzed and the results given to the field geologist promptly. The method reported in this paper was developed to meet this need. Speed is acquired by elimination of the customary drying and controlled ashing; the fresh vegetation is ashed in an open dish over a gasoline stove. The ash is put into solution with hydrochloric acid and the solution buffered. A chromograph is used to make a confined spot with an aliquot of the ash solution on dimethylglyoxime reagent paper. As little as 0.025% nickel in plant ash can be determined. With a simple modification, 0.003% can be detected. Data are given comparing the results obtained by an accepted laboratory procedure. Results by the field method are within 30% of the laboratory values. The field method for nickel in plants meets the requirements of biogeochemical prospecting with respect to accuracy, simplicity, speed, and ease of performance in the field. With experience, an analyst can make 30 determinations in an 8-hour work day in the field.

  4. Epicutaneous exposure to nickel induces nickel allergy in mice via a MyD88-dependent and interleukin-1-dependent pathway.

    Vennegaard, Marie T; Dyring-Andersen, Beatrice; Skov, Lone; Nielsen, Morten M; Schmidt, Jonas D; Bzorek, Michael; Poulsen, Steen S; Thomsen, Allan R; Woetmann, Anders; Thyssen, Jacob P; Johansen, Jeanne D; Odum, Niels; Menné, Torkil; Geisler, Carsten; Bonefeld, Charlotte M


    Several attempts to establish a model in mice that reflects nickel allergy in humans have been made. Most models use intradermal injection of nickel in combination with adjuvant to induce nickel allergy. However, such models poorly reflect induction of nickel allergy following long-lasting epicutaneous exposure to nickel. To develop a mouse model reflecting nickel allergy in humans induced by epicutaneous exposure to nickel, and to investigate the mechanisms involved in such allergic responses. Mice were exposed to NiCl2 on the dorsal side of the ears. Inflammation was evaluated by the swelling and cell infiltration of the ears. T cell responses were determined as numbers of CD4+ and CD8+ T cells in the draining lymph nodes. Localization of nickel was examined by dimethylglyoxime staining. Epicutaneous exposure to nickel results in prolonged localization of nickel in the epidermis, and induces nickel allergy in mice. The allergic response to nickel following epicutaneous exposure is MyD88-dependent and interleukin (IL)-1 receptor-dependent, but independent of toll-like receptor (TLR)-4. This new model for nickel allergy that reflects epicutaneous exposure to nickel in humans shows that nickel allergy is dependent on MyD88 and IL-1 receptor signalling, but independent of TLR4. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  5. Synthesis and Characterization of Chloridobis(dimethylglyoximato4-(2-ferrocenylvinylpyridinecobalt(III: A New Heterobinuclear Cobaloxime

    Sebastián Pizarro


    Full Text Available The synthesis of a new heterobinuclear cobaloxime with 4-(2-ferrocenylvinylpyridine, fcvpy, is reported. The complex [CoCl(dmgH2(fcvpy], where dmgH2 is dimethylglyoxime and dmgH is dimethylglyoximato, has been characterized by 1H-NMR, UV-Vis, cyclic voltammetry, and elemental analysis. The cyclic voltammogram of this complex shows a fc/fc+ reversible wave at +0.58 V versus Ag/AgCl, one irreversible wave, Epc = −0.54 V versus Ag/AgCl, assigned to the reduction of Co(III to Co(II, and two quasireversible processes at −1.02 V and −1.10 V versus Ag/AgCl associated with the reduction of Co(II. The complex showed ferrocene-ligand charge transfer bands at 334 nm and 505 nm. TDDFT/B3LYP/6-31G(d calculations support this assignation.

  6. Cobaloxime-based artificial hydrogenases.

    Bacchi, Marine; Berggren, Gustav; Niklas, Jens; Veinberg, Elias; Mara, Michael W; Shelby, Megan L; Poluektov, Oleg G; Chen, Lin X; Tiede, David M; Cavazza, Christine; Field, Martin J; Fontecave, Marc; Artero, Vincent


    Cobaloximes are popular H2 evolution molecular catalysts but have so far mainly been studied in nonaqueous conditions. We show here that they are also valuable for the design of artificial hydrogenases for application in neutral aqueous solutions and report on the preparation of two well-defined biohybrid species via the binding of two cobaloxime moieties, {Co(dmgH)2} and {Co(dmgBF2)2} (dmgH2 = dimethylglyoxime), to apo Sperm-whale myoglobin (SwMb). All spectroscopic data confirm that the cobaloxime moieties are inserted within the binding pocket of the SwMb protein and are coordinated to a histidine residue in the axial position of the cobalt complex, resulting in thermodynamically stable complexes. Quantum chemical/molecular mechanical docking calculations indicated a coordination preference for His93 over the other histidine residue (His64) present in the vicinity. Interestingly, the redox activity of the cobalt centers is retained in both biohybrids, which provides them with the catalytic activity for H2 evolution in near-neutral aqueous conditions.

  7. Forced-flow chromatographic determination of calcium and magnesium with continuous spectrophotometric detection

    Arguello, M.D.


    Modifications to the forced-flow chromatograph include a flow-through pH monitor to continuously monitor the pH of the final effluent and an active low-pass filter to eliminate noise in the spectrophotometric detector. All separations are performed using partially sulfonated XAD-2 as the ion exchanger. Elution of calcium and magnesium is accomplished using ammonium chloride and ethylenediammonium chloride solutions. Calcium and magnesium are detected by means of Arsenazo I and PAR-ZnEDTA color-forming reagents. Other metal ions are detected by means of PAR and Chromazurol S color-forming reagents. Calcium and magnesium distribution coefficients on partially sulfonated XAD-2 as functions of ammonium chloride and ethylenediammonium chloride concentration are given together with distribution coefficients of other metal ions. Methods for the selective elution of interfering metal ions prior to the elution of calcium and magnesium are described. Beryllium and aluminum are selectively eluted with sulfosalicylic acid. Those elements forming anionic chloride complexes are selectively eluted with HCl-acetone. Nickel is selectively eluted with HCl-acetone-dimethylglyoxime. Synthetic samples containing calcium and magnesium, both alone and in combination with alkali metals, strontium, barium, beryllium, aluminum, transition metals, and rare earths, are analyzed. Hard water samples are analyzed for calcium and magnesium and the results compared to those obtained by EDTA titration, atomic absorption spectroscopy, and plasma emission spectroscopy. Several clinical serum samples are analyzed for calcium and magnesium and the results compared to those obtained by atomic absorption spectroscopy.

  8. The electron-transfer based interaction between transition metal ions and photoluminescent graphene quantum dots (GQDs): a platform for metal ion sensing.

    Huang, Hongduan; Liao, Lei; Xu, Xiao; Zou, Mingjian; Liu, Feng; Li, Na


    The electron-transfer based quenching effect of commonly encountered transition metal ions on the photoluminescence of grapheme quantum dots (GQDs) was for the first time investigated, and was found to be associated with electron configuration of the individual metal ion. Ethylene diamine tetraacetic acid (EDTA), the metal ion chelator, can competitively interact with metal ions to recover the quenched photoluminescence of GQDs. Basically, metal ions with empty or completely filled d orbits could not quench the photoluminescence of GQDs, but this quenching effect was observed for the metal ions with partly filled d orbits. Based on the quenching-recovering strategy, a simple optical metal sensing platform was established by taking Ni(2+) as an example. Using the nickel ion-specific chelating reagent, dimethylglyoxime (DMG), to replace EDTA, a detection limit of 4.1 μM was obtained in standard solution. This proposed strategy does not need further functionalization of GQDs, facilitating the application for simple, fast and cost-effective screening of metal ions.

  9. Aplicação da análise de componentes principais no estudo da voltametria adsortiva de íons metálicos

    Leandra de Oliveira Cruz da Silva


    Full Text Available A voltametria adsortiva de redissolução catódica com pulso diferencial foi utilizada para um estudo exploratório de formasimultânea de íons cádmio, cobalto, cobre, níquel, chumbo e zinco em meio aquoso contendo uma mistura dos agentes complexantesdimetilglioxima e oxina. Voltamogramas individuais foram obtidos para as 64 soluções que compõem o planejamento experimentalutilizado e os dados de corrente foram submetidos à análise das componentes principais (PCA, permitindo caracterizar as tendênciasdas soluções dos íons metálicos estudados. O sistema pode ser descrito em oito componentes principais que explicaram 98,32% davariância. Sendo que as três primeiras componentes principais acumularam cerca de 85.46% da variância total.Abstract The adsorptive stripping voltammetry withdifferential pulse cathodic through the use of a mixture ofcomplexing agents dimethylglyoxime and oxine was used for anexploratory study simultaneously of ions cadmium, cobalt,copper, nickel, lead and zinc. Were obtained voltammograms ofthe 64 individual solutions used in planning and current datawere submitted to principal component analysis (PCA, allowingto characterize the trends of the solutions of metal ions studied.The system can be described in eight principal components thatexplained 98.32% of variance. Since the first three principalcomponents accumulated approximately 85.46% of the totalvariance.

  10. Quantitative colorimetric-imaging analysis of nickel in iron meteorites.

    Zamora, L Lahuerta; López, P Alemán; Fos, G M Antón; Algarra, R Martín; Romero, A M Mellado; Calatayud, J Martínez


    A quantitative analytical imaging approach for determining the nickel content of metallic meteorites is proposed. The approach uses a digital image of a series of standard solutions of the nickel-dimethylglyoxime coloured chelate and a meteorite sample solution subjected to the same treatment as the nickel standards for quantitation. The image is processed with suitable software to assign a colour-dependent numerical value (analytical signal) to each standard. Such a value is directly proportional to the analyte concentration, which facilitates construction of a calibration graph where the value for the unknown sample can be interpolated to calculate the nickel content of the meteorite. The results thus obtained were validated by comparison with the official, ISO-endorsed spectrophotometric method for nickel. The proposed method is fairly simple and inexpensive; in fact, it uses a commercially available digital camera as measuring instrument and the images it provides are processed with highly user-friendly public domain software (specifically, ImageJ, developed by the National Institutes of Health and freely available for download on the Internet). In a scenario dominated by increasingly sophisticated and expensive equipment, the proposed method provides a cost-effective alternative based on simple, robust hardware that is affordable and can be readily accessed worldwide. This can be especially advantageous for countries were available resources for analytical equipment investments are scant. The proposed method is essentially an adaptation of classical chemical analysis to current, straightforward, robust, cost-effective instrumentation. Copyright © 2010 Elsevier B.V. All rights reserved.

  11. Synthesis and structure of new mononuclear octahedral cobalt(III) dioximates derived from isonicotinic hydrazide

    Cocu, Maria; Bulhac, Ion; Coropceanu, Eduard; Melnic, Elena; Shova, Sergiu; Ciobanica, Olga; Gutium, Victoria; Bourosh, Paulina


    New organic ligand L (1) resulting from isonicotinic hydrazide and 2,4-pentanedione has been prepared and investigated by physicochemical methods, including elemental analysis, 1H and 13C NMR, IR spectroscopy and X-ray studies. The X-ray investigation revealed that the condensation of 2,4-pentanedione with isonicotinic hydrazide is accompanied by the formation of a five-membered ring including three carbon atoms of 2,4-pentanedione and two nitrogen atoms of the isonicotinic hydrazide fragment. The reaction between [Co(DfgH)2Br(H2O)] (DfgH2 = diphenylglyoxime) and L resulted in the formation of the mononuclear octahedral complex [Co(DfgH)2BrL] (2) with the substitution of the water molecule in the apical position by the ligand L. The reaction starting from [Co(DmgH)2Cl(H2O)] (DmgH = dimethylglyoxime) and L resulted in the mononuclear octahedral Co(III) complex with the composition [Co(DmgH)2ClL‧] (3), where L‧ unexpectedly represents a dehydrated derivative of L. The two coordination compounds are characterized by X-ray diffraction method. The IR, 1H NMR spectral studies of new compounds are also reported.

  12. Determination of trace cobalt concentrations in human serum by adsorptive stripping voltammetry.

    Kajic, Petra; Milosev, Ingrid; Pihlar, Boris; Pisot, Venceslav


    The goal of our study was to develop an accurate and reliable method for determining trace cobalt concentrations in human serum. The method was used to determine cobalt in the sera of healthy persons and patients with orthopaedic implants containing cobalt - a possible source of systemic release of cobalt into the human body. This goal is of vital interest since cobalt and its compounds are classified by IARC as potentially carcinogenic to humans. We used an electrochemical method, adsorptive stripping voltammetry (AdSV), which made possible the low detection limit and high sensitivity needed for measurements in human serum. The serum was acid digested by a combination of H2SO4, HNO3 and H2O2 in a 10 mL Kjeldhal flask. The digested sample was then dissolved in 0.1 mol/L ammonia buffer, pH 9.0 +/- 0.2. The determination is based on the adsorptive collection of the complex of cobalt (II) with dimethylglyoxime on a hanging mercury drop electrode (HMDE). The optimum values of adsorption potential and time were determined to be -0.8 V and 60 s. The optimisation of the sample digestion protocol and measurement procedures ensured the reliable assessment of low cobalt concentrations, down to 0.03 microg/L. The mean concentration of serum cobalt in four healthy persons was 0.11 +/- 0.06 microg/L, and in four patients with total hip replacements 0.34 +/- 0.07 microg/L. This method will be used routinely for measuring serum cobalt levels in patients with total hip replacements.

  13. 容量法测定钴镍试样中锌%Determination of Zinc in Specimen of Cobalt and Nickel by Volumetric Analysis Methods

    李蓉; 李啸寅; 郭春阳


    By precipitating cobalt and nickel in the media of ammonia-ammonia chloride with l-(2-pyridylazo) -2-naphthol (PAN) and dimethylglyoxime, the determination method of zinc by the EDTA titrimetry was put forward. The experimental research on the dosage, the precipitation conditions, and the separating situation for cobalt and nickel and their separation amount of two precipitators were carried out. The effects of seal and interference from cobalt ions and nickel ions on xylenol orange have been eliminated. The recovery of zinc was 99. 90% ~ 100. 10%. This method has been successfully applied to the determination of zinc in specimen of cobalt and nickel by the EDTA titrimetry due to its simplicity, convenience and accurate result.%提出了在氨-氯化铵介质中用1-(2-吡啶偶氮)-2-萘酚(简称PAN)及丁二酮肟沉淀分离钴、镍,EDTA容量法测定锌的方法.分别对两种沉淀剂的用量、沉淀条件、钴、镍分离情况及分离量进行了试验研究,消除了钴、镍离子对二甲酚橙的封闭干扰作用,锌的回收率:99.90%~100.10%.已成功地应用于含钴、镍试样中EDTA滴定法测定锌含量.

  14. Electron transfer reactions of macrocyclic compounds of cobalt

    Heckman, R.A.


    The kinetics and mechanisms of reduction of H/sub 2/O/sub 2/, Br/sub 2/, and I/sub 2/ by various macrocyclic tetraaza complexes of cobalt(II), including Vitamin B/sub 12r/, were studied. The synthetic macrocycles studied were all 14-membered rings which varied in the degree of unsaturation,substitution of methyl groups on the periphery of the ring, and substitution within the ring itself. Scavenging experiments demonstrated that the reductions of H/sub 2/O/sub 2/ produce free hydroxyl radicals only in the case of Co((14)ane)/sup 2 +/ but with none of the others. In the latter instances apparently H/sub 2/O/sub 2/ simultaneously oxidizes the metal center and the ligand. The reductions of Br/sub 2/ and I/sub 2/ produce an aquohalocobalt(III) product for all reductants (except B/sub 12r/ + Br/sub 2/, which was complicated by bromination of the corrin ring). The mechanism of halogen reduction was found to involve rate-limiting inner-sphere electron transfer from cobalt to halogen to produce a dihalide anion coordinated to the cobalt center. This intermediate subsequently decomposes in rapid reactions to halocobalt(III) and halogen atom species or reacts with another cobalt(II) center to give two molecules of halocobalt(III). The reductions of halomethylcobaloximes and related compounds and diamminecobaloxime by Cr/sup 2 +/ were also studied. The reaction was found to be biphasic in all cases with the reaction products being halomethane (for the halomethylcobaloximes), Co/sup 2 +/ (in less than 100 percent yield), a Cr(III)-dimethylglyoxime species, a small amount of free dmgH/sub 2/, and a highly-charged species containing both cobalt and chromium. The first-stage reaction occurs with a stoichiometry of 1:1 producing an intermediate with an absorption maximum at 460 nm for all starting reagents. The results were interpreted in terms of inner-sphere coordination of the cobaloxime to the Cr(II) and electron transfer through the oxime N-O bond.

  15. The renewable bismuth bulk annular band working electrode: fabrication and application in the adsorptive stripping voltammetric determination of nickel(II) and cobalt(II).

    Baś, Bogusław; Węgiel, Krystian; Jedlińska, Katarzyna


    The paper presents the first report on fabrication and application of a user friendly and mercury free electrochemical sensor, with the renewable bismuth bulk annular band working electrode (RBiABE), in stripping voltammetry (SV). The sensor body is partly filled with the internal electrolyte solution, in which the RBiABE is cleaned and activated before each measurement. Time of the RBiABE contact with the sample solution is precisely controlled. The usefulness of this sensor was tested by Ni(II) and Co(II) traces determination by means of differential pulse adsorptive stripping voltammetry (DP AdSV), after complexation with dimethylglyoxime (DMG) in ammonia buffer (pH 8.2). The experimental variables (composition of the supporting electrolyte, pre-concentration potential and time, potential of the RBiABE activation, and DP parameters), as well as possible interferences, were investigated. The linear calibration graphs for Ni(II) and Co(II), determined individually and together, in the range from 1×10(-8) to 70×10(-8)molL(-1) and from 1×10(-9) to 70×10(-9)molL(-1) respectively, were obtained. The calculated limit of detection (LOD), for 30s of the accumulation time, was 3×10(-9)molL(-1) for Ni(II) in case of a single element's analysis, whereas the LOD was 5×10(-9)molL(-1) for Ni(II) and 3×10(-10)molL(-1) for Co(II), when both metal ions were measured together. The repeatability of the Ni(II) and Co(II) adsorptive stripping voltammetric signals obtained at the RBiABE were equal to 5.4% and 2.5%, respectively (n=5). Finally, the proposed method was validated by determining Ni(II) and Co(II) in the certified reference waters (SPS-SW1 and SPS-SW2) with satisfactory results.

  16. 镍(Ⅱ)离子全自动在线分析仪的研发与应用%Design and application of on-line nickel analyzer

    许彦卿; 王艳; 洪陵成; 刘超


    A new kind of flow injection on-line nickel analyzer for fast and accurate determination of nickel ion in industrial wastewater was developed .The device was based on a soluble red wine color com-plex formation between nickel ion and dimethylglyoxime (C4 H8 N2 O2 ) in sodium hydroxide (NaOH) solu-tion medium with ammonium persulfate (C4 H8 N2 O2 ) as the oxidant .The absorbance at 465 nm was pro-portional to the concentration of nickel ion in aqueous solution in the range of 0.05-8 mg/L .The detection limit was 0.002mg/L (3σ) .The concentralion of Ni2+ for 0 .5 ,3 .0 and 6 .0mg/L were determined ,and the relative standard deviations (n=11) were 0 .11% ,0 .12% and 0 .15% 0 .5 ,3 .0 and 6 .0 mg/L respec-tively .%设计了水中镍(Ⅱ)自动在线分析仪,优化了仪器的最佳测试条件,并用该仪器用于环境水样中Ni(Ⅱ)的测定。在NaOH(pH=12)介质中,以过硫酸铵为氧化剂,镍与丁二酮肟作用形成酒红色可溶性络合物,于波长465 nm处进行测定。方法在0.1~8.0 mg/L范围内呈良好线性关系,对浓度为0.5 mg/L、3 mg/L、6 mg/L的镍离子溶液进行测定,相对标准偏差分别为0.11%、0.12%、0.15%。方法的检出限为0.002 m g/L (3σ)。仪器操作简便、消耗试剂量少、测定快速、灵敏、适于现场即时监测。

  17. LiCoxNiyMn1-x-yO2中镍、钴、锰的快速测定%Rapid determination of nickel, cobalt and manganese content in LiCoxNiyMn1- x- yO2

    谭静进; 吴开洪; 张敏; 谢明宏


    研究了丁二酮肟沉淀分离-乙二胺四乙酸二钠滴定法测定LiCoxNiyMn1-x-yO2(0<x,0<y,x+y<1)中镍含量,得到准确快速测定镍含量的最佳操作条件为:加入30 ml 15%酒石酸溶液、20 ml 50%乙酸铵溶液,沉淀时的pH=6.5、陈化时间为0 min;采用电位滴定法准确快速测定锰;提出以二甲酚橙为指示剂,在pH值为6.0~6.2的六次甲基四胺缓冲介质中、100℃下,以EDTA滴定法测定镍、锰和钴的总量,利用差减法推算出钴含量.本方法的相对标准偏差小于0.71%,回收率为97.40% ~ 101.60%,耗时不到60 min,实现了LiCoxNiyMn1-x-yO2中镍、钴、锰的准确快速测定.%The determination method of nickel content in LiCoxNiyMn-x-yO2(0 < x ,0 < y, x + y < l)by using dimethylgly-oxime precipitate separation-disodium ethylenediaminetetraacetate dihydrate titration was studied, the optimum operating conditions for precise and rapid determination of nickel content were: adding 30 ml 15% tartaric acid solution and 20 ml 50% ammonium acetate solution,the pH value was 6.5 when nickel was precipitating and the aging time was 0 min.The potentiometric method was used for determining manganese content precisely and rapidly. The EDTA titration method was also put forward to determine the total content of nickel,cobalt and manganese by using xylenol orange as indicator and hexamethylenetetramine(pH = 6.0 ~ 6.2)as buffer mediator and under 100 °C . The content of cobalt was calculated indirectly after aforementioned determination. The RSD of this method was below 0.71% ,the recovery rate was between 97.40% ~ 101.60% and the time was less than 60 min.the precise and rapid determination of nickel,cobalt and manganese content in LiCoxNiyMn-x-yO2 was realized.

  18. Determination of palladium in palladium oxide by EDTA titration with hydrazine hydrate reduction%水合肼还原-ED TA 滴定法测定氧化钯中钯

    王艳红; 宫嘉辰; 张瑞峰


    氧化钯使用常规的酸溶方法难溶。采用水合肼作为还原剂,于80℃时,在氧化钯的悬浮水溶液中,将氧化钯还原为金属钯黑,过滤后,该金属钯黑连同滤纸经过盐酸及硝硫混酸碳化处理后,钯进入溶液,从而解决了难溶氧化钯的溶样难题。然后,于pH 5.8的醋酸‐醋酸钠缓冲介质中,以二甲酚橙为指示剂,锌盐返滴定过量EDTA ,用丁二酮肟析出与钯等量的ED‐TA ,三氯甲烷萃取丁二酮肟‐钯沉淀,锌盐滴定析出的EDTA以测定钯含量,从而建立了水合肼还原‐EDTA滴定法测定难溶氧化钯中钯的方法。按照实验方法测定实际样品中钯,结果的相对标准偏差(RSD ,n=5)在0.12%~0.20%之间。对基准物质氧化钯中钯进行分析,测定值与理论值相符合。%The palladium oxide was hardly dissolved by the common acid method .In proposed study ,the palladium oxide was reduced to the metal palladium black in supernatant solution at 80 ℃ using hydrazine hydrate as reducing agent .After filtration ,the metal palladium black with filter paper was treated by car‐bonization with hydrochloric acid and nitric‐sulfuric acid .The palladium was introduced into solution ,sol‐ving the sample preparation problem of indissolvable palladium oxide .Then ,the excessive EDTA was back‐titrated with zinc salt in HAc‐NaAc buffer solution at pH 5.8 using xylenol orange as indicator .The equal amount of EDTA to palladium was precipitated with dimethylglyoxime .The dimethylglyoxime‐palla‐dium precipitate was extracted with trichloromethane .The precipitated EDTA was titrated with zinc salt to determine the content of palladium .T hus ,the determination method of palladium in indissolvable palla‐dium oxide by EDTA titration with hydrazine hydrate reduction was established .The content of palladium in actual sample was determined according to the experimental method .The relative standard

  19. Kinetic and mechanistic studies of reactive intermediates in photochemical and transition metal-assisted oxidation, decarboxylation and alkyl transfer reactions

    Carraher, Jack McCaslin

    leads to the dissociation of H2O2 from Cr(III), while in the H+-independent reaction, CraqOOH2+ is transformed to Cr(V). Both scavengers rapidly remove Cr(V) and simplify both the kinetics and products by impeding formation of Cr(IV, V, VI). Syntheses, Reactivity, and Thermodynamic Considerations LRhR2+. Macrocyclic rhodium(II) complexes LRh(H 2O)2+ (L = L1= cyclam and L2 = meso-Me6-cyclam) react with alkyl hydroperoxides R(CH3)2COOH to generate the corresponding rhodium(III) alkyls LRh(H2O)R2+ (R = CH3, C2 H5, PhCH2). Methyl and benzyl complexes can also be prepared by bimolecular group transfer from alkyl cobaloximes (dmgX) 2(H2O)CoR (where R = CH3, CH2Ph and dmgX is either dimethylglyoxime or a BF2-capped derivative of dmg) to LRh(H2O)2+. When R = C2H5, C3H7 or C4H9, the mechanism changes from group transfer to hydrogen atom abstraction from the coordinated alkyl and produces LRh(H2O)H2+ and an a-olefin. The new LRh(H2O)R2+ complexes were characterized by solution NMR and by crystal structure analysis. They exhibit great stability in aqueous solution at room temperature, but undergo efficient Rh-C bond cleavage upon photolysis. 'Green' Model for Decarboxylation of Biomass Derived Acids via Photolysis of in situ formed Metal-Carboxylate Complexes. Photolysis of aqueous solutions containing propionic acid and Fe 3+ aq in the absence of oxygen generates a mixture of hydrocarbons (ethane, ethylene and butane), carbon dioxide, and Fe2+. Photolysis in the presence of O2 yields catalytic amounts of hydrocarbon products. When halide ions are present during photolysis; nearly quantitative yields of ethyl halides are produced via extraction of a halide atom from FeX2+ by ethyl radical. The rate constants for ethyl radical reactions with FeCl2+ (k = 4.0 (+/- 0.5) x 106 M-1s-1) and with FeBr 2+ (k = 3.0 (+/- 0.5) x 107 M-1s -1) were determined via competition reactions. Irradiation of solutions containing aqueous Cu2+ salts and linear carboxylic acids yield alpha