ICP-AES法测量铍钴铜合金中主量元素铍、钴的含量

建立ICP–AES法测定铍钴铜合金中主量元素铍、钴含量的方法。将试样用硝酸、盐酸溶解,在钇内标存在的情况下以等离子体光源激发,并分别选择分析谱线Be 313.1 nm,Co 228.6 nm进行光谱测定。铍、钴含量在0~5%范围内与光谱强度线性相关,铍、钴两元素线性相关系数分别为0.999 18,0.999 91;检出限分别为0.000 12%,0.001 1%;测定结果的相对标准偏差为0.25%~4.59%;回收率在96%~102%之间。该方法操作简单实用,可同时测定铍、钴两元素,测定结果准确可靠。     

Effects of ionic strength and pH on the stability constants of the complex of Co(II) with soil fulvic acid

The stability constants for tracer concentrations of Co(II) complexes with the red earth fulvic acid were determined at pH 3.8–6.8 and ionic strength 0.0010–1.0 mol/l by using the cation exchange equilibrium method and the radiotracer⁶⁰Co. The effects of ionic strength and pH on the stability constants of 1∶1 Co(II) complexes were investigated, and it was found that the stability constants of complexes of humic substances do not vary with ionic strength and pH in a manner similar to that of simple complexes.     

Fullerene/cobalt porphyrin hybrid nanosheets with ambipolar charge transporting characteristics

A novel supramolecular nanoarchitecture, comprising C(60)/Co porphyrin nanosheets, was prepared by a simple liquid-liquid interfacial precipitation method and fully characterized by means of optical microscopy, AFM, STEM, TEM, and XRD. It is established that the highly crystalline C(60)/Co porphyrin nanosheets have a simple (1:1) stoichiometry, and when incorporated in bottom-gate, bottom-contact field-effect transistors (FETs), they show ambipolar charge transport characteristics.     

Application of electrospray ionization tandem mass spectrometry for the rapid and sensitive determination of cobalt in urine

Recently, cobalt (Co) is reported to be taken as a supplement by athletes for improving anaerobic performance. For the diagnosis of abuse, the limit of detection (LOD) of Co in the analysis should be lower than the concentrations of Co in plasma and urine of normal persons. A simple, rapid and sensitive method has been developed for the determination of Co in urine. Co was complexed with diethyldithiocarbamate (DDC) and extracted with isoamyl alcohol in the presence of citric acid. The detection of Co was achieved by injecting a 1-μL aliquot of isoamyl alcohol containing Co-DDC complex directly into an electrospray ionization tandem mass spectrometric (ESI-MS-MS) instrument without chromatographic separation. The quantification was performed using selected reaction monitoring at m/z 291 of the product ion Co(C₄H₁₀NCS)₂⁺ which was produced by collision-induced dissociation from the precursor ion Co(DDC)₂⁺ at m/z 355. ESI-MS-MS data were obtained in less than 10 min with an LOD of 0.05 μg L⁻¹ and a linear calibration range of 0.1-100 μg L⁻¹ using 10 μL of urine. The procedure was validated with certified reference materials (SRM 2670a and SRM 1643e). This method is suitable for the analysis of Co in the laboratories already equipped with an ESI-MS-MS instrument.     

Co2+与BPPT络合反应动力学及动力学光谱法测定钴

Thiosemicarbazones and phenylthiosemicarbazones are in- teresting ligands because of their ability to form highly stable and intensely colored complexes, which is attributed to the for- mation of bond between sulfur and hydrazino nitrogen atoms, and these…     

H-point standard addition method for simultaneous spectrophotometric determination of Co(II) and Ni(II) by 1-(2-pyridylazo)2-naphthol in micellar media

A very simple and selective spectrophotometric method for simultaneous determination of Co(II) and Ni(II) by 1-(2-pyridylazo) 2-naphthol (PAN), in micellar media, using H-point standard addition method (HPSAM) is described. The ligand and its metal complexes (Co(II)-PAN and Ni(II)-PAN) were made water-soluble by the neutral surfactant Triton X-100, and therefore, no extraction with organic solvents was required. Formation of both the complexes was complete within 10 min at pH 9 (adjusted by ammonia buffer). The linear range was 0.10-2.00 microg ml(-1) for Co(II) and 0.05-1.50 microg ml(-1) for Ni(II). The relative standard deviation (R.S.D.) for the simultaneous determination of 0.50 microg ml(-1) each of Co(II) and Ni(II) was 2.32 and 3.13%, respectively. Interference effects of common anions and cations were studied and the method was applied to simultaneous determination of Co(II) and Ni(II) in alloy samples. The method was compared with derivative spectrophotometric method.     

Enhancing the Kinetic Process in Biphasic Crystalline NiWO4/Amorphous Co-B Electrode Materials toward Energy Storage with Ultrahigh Rate Performance

Here, we report a two-phase crystalline NiWO₄/amorphous Co−B nanocomposite as an electrode material for supercapacitors, which is effectively synthesized via a simple hydrothermal method and chemical precipitation method. The obtained NiWO₄/Co−B exhibits crystal-amorphous contact, which makes it have more active sites than other crystalline-crystalline phase boundaries, thereby enhancing electron transport. The NiWO₄/Co−B electrode with the best mass ratio of crystalline and amorphous exhibits a great specific capacitance and excellent cycle durability. Compared to individual Co−B and NiWO₄, it also shows enhanced rate capability Besides, NiWO₄/Co−B/activated carbon supercapacitor device can provide a good specific capacitance and a maximum energy density of 10.92 Wh kg⁻¹ at 200 W kg⁻¹. This work provides new insights to develop novel electrode materials for energy storage and conversion.     

Selective thin-layer chromatography of 4-R-1,2,4-triazoles

A convenient and selective TLC of 4-R-1,2,4-triazoles (Rtrz) and nitrogen containing aromatic rings is presented (molecules 1-11). This simple revelation method implies a complexation of heterocycles to Co(II) ions on a TLC plate, followed by a subsequent modification of the reduction potential which enables oxidation of Co(II) by permanganate.     

Highly Sensitive Determination of Traces of Co(II) in Pharmaceutical and Urine Samples Using Kinetic–Spectrophotometric Method

Abstract

A high sensitive, accurate and simple kinetic method has been developed for determination of trace of Co(II) ions, based on its strongly catalytic effect in the reaction oxidation of disodium-6-hydroxy-5-[(4-sulfophenyl)azo]-2-naphtalenesulfonic acid (artificial color, Sunset Yellow FCF, E110 in text selected as SY) by hydrogen peroxide in borate buffer at pH of 9.5, by monitoring the rate of disappearance of SY. Reaction rate was monitored spectrophotometrically, at λ_max of the SY at 478.4 nm. The optimum operating conditions regarding reagents concentration and temperature were established. The tangent method was adopted for constructing the calibration curve, which was found to be linear over the concentration range 1.18–17.67 ng ml^?1 and 17.67–58.90 ng ml^?1 of Co(II). The limit of detection (3σ) is 0.15 ng ml^?1, and limit of quantification (10σ) is 0.5 ng ml^?1. The effects of the other ions on the reaction rate were determined for an assessment of the selectivity of the method. The developed kinetic procedure was successfully applied for the determination of Co(II) in pharmaceutical and urine samples. The unique features of this procedure are that the determination can be performed at room temperature, and the analysis time is short. The newly developed method is high sensitive, simple, inexpensive and efficient for use in the analysis of a large number of samples.     

Yields of Photo-Proton Reactions on Nuclei of Nickel and Separation of Cobalt Isotopes from Irradiated Targets

Nowadays, cobalt isotopes ⁵⁵Co, ⁵⁷Co, and ^58mCo are considered to be promising radionuclides in nuclear medicine, with ⁵⁵Co receiving the most attention as an isotope for diagnostics by positron emission tomography. One of the current research directions is dedicated to its production using electron accelerators (via photonuclear method). In our work, the yields of nuclear reactions occurring during the irradiation of ^natNi and ⁶⁰Ni by bremsstrahlung photons with energy up to 55 MeV were determined. A method of fast and simple cobalt isotopes separation from irradiated targets using extraction chromatography was developed.     

Co(thd)2: a superior catalyst for aerobic epoxidation and hydroperoxysilylation of unactivated alkenes: application to the synthesis of spiro-1,2,4-trioxanes

Bis(2,2,6,6-tetramethyl-3,5-heptanedionato)cobalt(II) (Co(thd)₂), a β-diketonate prepared in a simple one-step procedure, is an excellent catalyst for aerobic epoxidation and Mukaiyama-Isayama hydroperoxysilylation of unactivated alkenes. For hydroperoxysilylation, Co(thd)₂ is superior to Co(acac)₂ and can catalyse oxidation of cyclic alkenes in excellent yield. Chiral β-diketonate or keto iminato catalysts failed to catalyse this reaction in an enantioselective manner and a free radical mechanism consistent with this observation is proposed. Hydroperoxysilylation of cyclohex-1-enylmethanol by Co(thd)₂ followed by addition of a ketone/TsOH provides a simple one-pot procedure for the synthesis of spiro-1,2,4-trioxane antimalarials.     

Selective determination of inorganic cobalt in nutritional supplements by ultrasound-assisted temperature-controlled ionic liquid dispersive liquid phase microextraction and electrothermal atomic absorption spectrometry

In the present work, a simple and rapid analytical method based on application of ionic liquids (ILs) for inorganic Co(II) species (iCo) microextraction in a variety of nutrient supplements was developed. Inorganic Co was initially chelated with 1-nitroso-2-naphtol (1N2N) reagent followed by a modern technique named ultrasound-assisted temperature-controlled ionic liquid dispersive liquid phase microextraction (USA-TILDLME). The extraction was performed with 1-hexyl-3-methylimidazolium hexafluorophosphate [C₆mim][PF₆] with the aid of ultrasound to improve iCo recovery. Finally, the iCo-enriched IL phase was solubilized in methanol and directly injected into an electrothermal atomic absorption spectrometer (ETAAS). Several parameters that could influence iCo microextraction and detection were carefully studied. Since the main difficulty in these samples is caused by high concentrations of potential interfering ions, different approaches were evaluated to eliminate interferences. The limit of detection (LOD) was 5.4 ng L^?1, while the relative standard deviation (RSD) was 4.7% (at 0.5 μg L^?1 Co level and n = 10), calculated from the peak height of absorbance signals. Selective microextraction of iCo species was achieved only by controlling the pH value during the procedure. The method was thus successfully applied for determination of iCo species in nutritional supplements.     

Flow injection analysis of Zn and Co in beverages, biological, environmental and pharmaceutical samples

A new, simple, rapid and selective flow injection analysis (FIA) method for the spectrophotometric quantification (speciation of inorganic and organic form) of Zn and Co with ammonium thiocyanate and malachite green (MG) in the presence of surfactants (CPC and TX-100) is described. The value of apparent molar absorptivity of the Zn- and Co- complexes are (1.23) × 10⁴ and (8.67) × 10³ L mol^–1cm^–1 at absorption maximum, 635 nm, respectively. The detection limit (amount causing a peak height > 3 s) is 15 ppb Zn and 20 ppb Co, whereas their optimum working ranges for the quantitative determinations are 0.05–2.0 ppm Zn and 0.07–2.5 ppm Co in the real samples. The sample thoughput of the method is 120 samples/h at the flow rate of 5.0 mL/min with rel. std. dev. of < ± 1%. The method is free from interferences of almost all ions which are commonly associated with these metals in the complex materials. The composition of the complexes and their reaction mechanism involved are discussed. The effect of FIA and analytical variables for the determination of the metals are optimized. The method has been applied to the quantification of Zn and Co in beverages, biological, environmental, and pharmaceutical samples.     

Flow Injection Chemiluminescence Determination of Gentamycin Using On-Line Electrogenerated Co(III) As the Oxidant

ABSTRACT

A novel flow-injection Chemiluminescence (CL) system for the determination of gentamycin is described, based on the direct chemiluminescence reaction of gentamycin and Co(III) in sulfuric acid media. The unstable strongly oxidative Co(III) was electrogenerated on-line with constant current electrolysis. The chemiluminescence intensity was linear with gentamycin concentrations of 0.01～80μg/ml, the detection limit being 0.005μg/ml. The whole process could be completed in 1 min with a relative standard deviation of less than 3.2%. The proposed method is rapid and simple and is suitable for automatic and continuous analysis. This method has been applied satisfactorily to the analysis of gentamycin in pharmaceutical preparations.     

Physicochemical properties of manganese-containing oxides with a spinel structure prepared with the use of ammonium nitrate and their catalytic activity in carbon monoxide oxidation

Oxide catalysts with the spinel structure with the molar ratios between components Co/Mn = 1: 2, Cu/Mn = 1: 2, and Cu/Co/Mn = 2: 2: 3 (samples I–III, respectively) have been prepared by the decomposition of metal nitrate hydrate solutions in an ammonium nitrate melt. Sample IV with the ratio Cu/Co/Mn = 2: 2: 3 containing 80% γ-Al₂O₃ is obtained by the addition of γ-Al₂O₃ powder to the initial melt. The catalysts are characterized using X-ray diffraction analysis, electron microscopy, and local X-ray analysis. Catalytic activity in the reaction of CO oxidation increased in the order I < II < III < IV. The proposed method is simple, and the synthesis is rapid. Oxides with the spinel structure homogeneous in composition and morphology without any impurities can be prepared by this method. These oxides exhibited high catalytic activity in the reaction of carbon monoxide oxidation.     

Simultaneous spectrophotometric determination of iron, nickel and cobalt in micellar media by using direct orthogonal signal correction-partial least squares method

A very simple and selective spectrophotometric method for simultaneous determination of iron(II), nickel(II) and cobalt(II) based on formation of their complexes with 1-(2-pyridylazo)-2-naphtol (PAN) in micellar media is described. Although the complexes of Fe(II), Ni(II) and Co(II) with reagent show a spectral overlap, they have been simultaneously determined by partial least squares (PLS) with and without preprocessing step using direct orthogonal signal correction (DOSC). The linear range was 0.30-4.50 μg ml⁻¹ for Co(II), 0.20-3.00 μg ml⁻¹ for Ni(II) and 0.30-5.00 μg ml⁻¹ for Fe(II). The results obtained by the PLS and DOSC-PLS were statistically compared. Interference effects of common anions and cations were studied and the proposed method was also applied satisfactorily to the determination of Fe(II), Ni(II) and Co(II) in synthetic samples.     

Simultaneous Electrochemical Detection of Co(II) and Cu(II) by 1‐Diazo‐2‐Naphthol‐4‐Sulfonic Acid/MWCNTs Modified Electrode

This work describes a simple preparation of 1‐diazo‐2‐naphthol‐4‐sulfonic acid (1,2,4‐acid) and multiwalled carbon nanotubes (MWCNTs) modified glassy carbon electrode (GCE) for the simultaneous detection of Co(II) and Cu(II). MWCNTs, with their good conductivity and large surface area, were drop‐casted onto the surface of the GCE prior to the electrodeposition of 1,2,4‐acid, a metal chelating agent. Co(II) and Cu(II) were simultaneously measured by differential pulse anodic stripping voltammetry (DPASV) in a batch system. Under optimum conditions, the linear range of Co(II) was between 0.10 and 2.5 μg mL⁻¹ with an LOD of 80 ng mL⁻¹. Two linear ranges were obtained for Cu(II), 0.0050 to 0.030 μg mL⁻¹ and 0.040 to 0.25 μg mL⁻¹,with an LOD of 2.4 ng mL⁻¹. The method offered a high operational stability for up to 52 measurements (RSD=3.4 % for Co(II) and 2.6 % for Cu(II)) and good reproducibility (RSD=1.2 % for Co(II) and 1.7 % for Cu(II)). In the simultaneous detection of Co(II) and Cu(II), there was no effect from common interferences found in wastewater. The method was successfully applied in real water samples with good recoveries (88.2±0.8 to 102.0±0.8 % for Co(II) and 96.5±0.4 to 103.8±0.9 % for Cu(II)) and the results were in good agreement with those obtained from inductively coupled plasma optical emission spectrometry (ICP‐OES) (P >0.05).     

Determination of trace metal ions by AAS in natural water samples after preconcentration of pyrocatechol violet complexes on an activated carbon column

A simple preconcentration method is described for the determination of Cu, Mn, Co, Cd, Pb, Ni and Cr in water samples by flame AAS. Trace metal ions in water were sorbed as pyrocatechol violet complexes on activated carbon column at the pH range of 4–8, then eluted with 1 M HNO₃ in acetone. The effect of major cations and anions of the natural water samples on the sorption of metal ions has been also investigated. The concentration of the metal ions detected after preconcentration was in agreement with the added amount. The present method was found to be applicable to the preconcentration of Cu, Mn, Co, Cd, Pb, Ni and Cr in natural water samples with good results such as R.S.D. from 3 to 8% (N=10) and detection limits under 70 ng l⁻¹.     

Simultaneous Determination of Nickel and Cobalt Using a Solid Bismuth Vibrating Electrode by Adsorptive Cathodic Stripping Voltammetry

A simple, fast, sensitive and greener voltammetric procedure for simultaneous analysis of nickel (Ni) and cobalt (Co) by square wave adsorptive cathodic stripping voltammetry (SW‐AdCSV) using a solid bismuth vibrating electrode is presented for the first time. The procedure enables to determine Ni together with Co, in ammonia buffer 0.1 M (pH 9.2) and in the presence of oxygen, and involves an adsorptive accumulation of metal‐dimethylglyoxime (Ni‐DMG and Co‐DMG) complexes on the electrode surface. For Ni and Co, the detection limits, obtained with 30 s of accumulation time, were 0.6 and 1.0 µg L^?1, respectively. The method was free of metals (Cd²⁺, Cr³⁺, Cr⁶⁺, Cu²⁺, Fe³⁺ and Pb²⁺ up to 50 µg L^?1, Al³⁺ and Mn²⁺ up to 500 µg L^?1; Zn²⁺ up to 300 µg L^?1) interferences up to the concentrations mentioned in brackets. The proposed method was validated for simultaneous determination of Ni and Co in a certified reference surface and river waters with good results.     

Simultaneous determination of cobalt and palladium in micellar media using H-point standard addition method and partial least square regression

A simple, sensitive and selective spectrophotometric method for the simultaneous determination of Co(II) and Pd(II) using partial least square (PLS) calibration and H-point standard addition method is described. The method is based on the complex formation of Co(II) and Pd(II) with 4-(2-pyridylazo) resorcinol (PAR) in acidic media and in the presence of sodium dodecyl sulfate (SDS) as a micellizing agent. Acidic media and the presence of a micellar system improve selectivity and sensitivity, respectively. By applying PLS calibration, Co(II) and Pd(II) can be determined in the range of 0.20-2.0 and 0.40-4.0 microg ml(-1), respectively. The relative errors of prediction for the determination of Co(II) and Pd(II) in the 10 prediction samples were 1.69 and 1.72%, respectively. The results of applying H-point standard addition method show that Co(II) and Pd(II) can be determined simultaneously with concentration ratio of Co(II) to Pd(II) varying between 7:1 and 1:8 in the mixed samples. Both proposed methods (PLS and HPSAM) were applied to the determination of Co(II) and Pd(II) in several alloy solutions with satisfactory results.