Spectrophotometric simultaneous determination of cobalt, copper and nickel using nitroso-R-salt in alloys by partial least squares

Partial least squares modeling as a powerful multivariate statistical tool applied to spectrophotometric simultaneous determination of cobalt, copper, and nickel in aqueous solutions. The concentration range for cobalt, copper and nickel were 0.4-2.6, 0.6-3.4, 0.5-5.5 ppm, respectively. The experimental calibration set was composed with 36 sample solutions using a mixture design for three component mixtures. The absorption spectra were recorded from 470 to 600 nm. The effect of pH on the sensitivity and selectivity was studied according to net analyte signal (NAS). The values of root mean square difference (RMSD) for cobalt, copper and nickel using partial least squares (PLS) were 0.0192, 0.0263 and 0.0446 ppm, respectively. The effects of various cations and anions were investigated. The method was used to determination of cobalt, copper and nickel in two sample alloys based on copper, nickel and cobalt (known as cunico) and based on cobalt, nickel and iron (known as conife).     

Simultaneous Preconcentration of Copper,Nickel and Cobalt In Water By Coprecipitation-Flotation For Electrothermal Atomic Absorption Spectrometry

Abstract

A method is described for the simultaneous flotation separation and determination of μg-levels of copper (II), nickel (II) and cobalt (II) in water. Copper, nickel and cobalt in a 1000-ml sample of water are coprecipitated with hydrated zirconium oxide at pH 9.1±0.1. The precipitate is floated with the aid of a surfactant solution and small air bubbles, separated and dissolved in dilute hydrochloric acid. The contents of these elements are determined by electrothermal atomic absorption spectrophotometry. The method is applied to the determination of low μg/1 levels of copper, nickel and cobalt in fresh water.     

Simultaneous extraction of trace amounts of cobalt, nickel and copper ions using magnetic iron oxide nanoparticles without chelating agent

The present study investigates the application of Fe₃O₄ nanoparticles as an adsorbent for solid phase extraction and their subsequent determination of trace amounts of cobalt, nickel and copper from environmental water samples using flame atomic absorption spectrometry. The analyte ions were adsorbed on magnetic nanoparticles in the pH range of 10–12 and then, Fe₃O₄ nanoparticles were easily separated from the aqueous solution by applying an external magnetic field and decantation. Hence, no filtration or centrifugation was needed. After extraction and collection of magnetic nanoparticles, the analyte ions were desorbed using 1.0 M HNO₃. Several factors that may affect the preconcentration and extraction process, including pH, type and volume of eluent, sample volume, salt effect and matrix effect were optimized. Under the optimized conditions, linearity was maintained from 0.005–3.0 μg/mL for cobalt and nickel and 0.001 to 1.25 μg/mL for copper in the initial solution. The detection limits of this method for cobalt, nickel and copper ions were 0.9, 0.7 and 0.3 ng/mL, respectively. Finally, the method was successfully applied to the extraction and determination of the analyte ions in natural waters and reference plant samples.     

Thermal and structural studies of the chloro complexes of cobalt,nickel and copper with 3-phenylpyridine

The chloro complexes of cobalt, nickel and copper with 3-phenylpyridine were prepared in ethanolic solution from which solid compounds were isolated. The cobalt and copper complexes have stoichiometry M₂LCl₄ while the nickel complex has stoichiometry NiLCl₂. The suggested structure for the cobalt and copper complexes is tetrahedral, while for the nickel complex it is octahedral. Thermal analysis studies show that the cobalt and copper complexes form intermediate complexes before their metal oxides are produced. The nickel complex also forms an intermediate complex and then nickel chloride before the nickel oxide is obtained.     

Study on Determination of Six Transition Metal Ions in Biological Samples by SPE and RP‐HPLC

This paper reports the utilization of solid phase extraction and the reversed‐phase high‐performance liquid chromatography (RP‐HPLC) for the determination of six transition metal ions (iron, cobalt, nickel, copper, zinc and manganese) in biological samples. The samples were digested by microwave digestion. The iron, cobalt, nickel, copper, zinc and manganese ions in the digested samples can react with 2‐(2‐quinolinylazo)‐5‐diethylaminophenol (QADEAP) to form colored chelates in pH 4.0 acetic acid‐sodium acetic buffer solutions and cetyl trimethylammonium bromide (CTMAB) medium. These chelates were enriched by solid phase extraction with C₁₈ cartridge. Then the chelates were separated on a Waters Nova‐Pak‐C₁₈ column (3.9 × 150 mm, 5 μm) by gradient elution with methanol (containing 0.5% of acetic acid and 0.1% of CTMAB) and 0.05 mol/L pH 4.0 acetic acid‐sodium acetic buffer solution (containing 0.1% of CTMAB) as mobile phase at a flow rate of 0.5 mL/min. The detection limits of iron, cobalt, nickel, copper, zinc and manganese are 3 ng/L, 4 ng/L, 2 ng/L, 4 ng/L, 8 ng/L, 10 ng/L, respectively. This method was applied to the determination of iron, cobalt, nickel, copper, zinc and manganese in biological samples with good results.     

Simultaneous spectrophotometric determination of traces of cobalt,nickel and copper with dithio-oxamide

The cobalt, nickel and copper complexes of dithio-oxamidc have been characterized in terms of color, effect of pH, structure in solidion, order of addition of reagents, adherence to Beer's law and sensitivity. The reactivity of the reagent to other ions has been reported. A method for the simultaneous spectrophotometric determination of cobalt, nickel and copper has been developed. the results of the application of this procedure to synthetic samples and to several National Bureau of Standards Samples are given.     

Omega chrome black blue G as a colorimetric reagent for the microdetermination of various cations

Summary Omega Chrome Black Blue G has been found to be a suitable colorimetric reagent for the detection of cobalt and for the determination of copper, cobalt, cadmium, lead and magnesium. The effects of time, p_H, temperature, and foreign ions on the absorbancy are investigated. The reagent is practically suitable for the determination of microgram amounts of cobalt in presence of nickel and other ions which evoke a red colour.The reagent is not suitable for the determination of nickel, calcium, strontium, and zinc.     

Simultaneous spectrophotometric determination of traces of cobalt,nickel and copper with n,n'-bis(3-dimethylaminopropyl)dithio-oxamide

The cobalt, nickel and copper complexes of N,N'-bis(3-dimethylaminopropyl)dithio-oxamide have been characterized in terms of color, effect of pH, rate of color formation, structure in solution, order of addition of reagents, adherence to Beer's law, and sensitivity. The reactivity of the reagent to other ions has been reported. A method for the simultaneous spectrophotometric determination of cobalt, nickel and copper has been developed. The results of the application of this procedure to synthetic samples and to several National Bureau of Standards samples are given.     

The sequential injection system with adsorptive stripping voltammetric detection

Two sequential injection systems have been developed for adsorptive stripping voltammetric measurement. One is for substances adsorbing at mercury, e.g. riboflavin. In this case, a simple arrangement with only sample aspiration is needed. Reproducibility was 3% and detection limit 0.07 μM. The measuring system was applied to determination of riboflavin in vitamin pills and to study the photodegradation process of riboflavin in aqueous solutions. In the second case, metal ions were determined. They have to be complexed before deposition on the mercury surface. Thus, both the sample and the ligand have to be aspirated in the system. In this case, the reproducibility was ≈6% and the detection limit <0.1 ppm for cadmium, lead and copper when complexation with oxine was used. Dimethylglyoxime was used in determination of nickel and cobalt and nioxime complexes were used in determination of nickel and copper. With these complexing agents, the reproducibility was the same as with oxine, but the metals could be determined at concentrations lower than 0.01 ppm. Application of two ligands in a SIA system with AdSV detection was also studied. Simultaneous determination of copper, lead, cadmium and cobalt was possible by using oxine and dimethylglyoxime. Copper and nickel were simultaneously determined by using dimethylglyoxime and nioxime.     

Investigations of Cobalt, Nickel, and Copper Diethyldithiocarbamates Using Thermal Lens Spectrometry

Thermal lens spectrometry was used to study the dissociation kinetics of diethyldithiocarbamate complexes of copper(II), cobalt(III), and nickel(II) as a function of pH in the presence of chloride and sulfate ions. It is shown that, as distinct from conventional spectrophotometric and potentiometric measurements, the reversible dissociation of the test complexes and the irreversible oxidation of the ligand can be studied separately (at a level of n × 10^–8–n × 10^–6 M) using thermal lens spectrometry. Because of work in more dilute solutions and due account of the kinetic features of the systems in question, thermal lens spectrometry provides a higher accuracy of the determination of stability constants for diethyldithiocarbamate complexes of copper(II), cobalt(III), and nickel(II). The adsorption of the diethyldithiocarbamate complexes in question from water–ethanol solutions (1 : 3) on Silasorb C₁₈ silica is studied, and the adsorption constants are determined. The limits of detection of copper(II), cobalt(III), and nickel(II) diethyldithiocarbamates obtained in extraction–thermal-lens determination are n × 10^–8 M.     

Synthesis of certain pyridinyl and diazinyl hydrazones containing one or more ferroin groups, and their chromogenic reactions with iron, copper, cobalt and nickel

Fifteen new hydrazones with one or more ferroin groups were prepared, and their chelation and chromogenic properties with iron(II), copper(I), cobalt(II) and nickel(II) were investigated. Improved sensitivity in the spectrophotometric determination of cobalt, copper, and nickel is provided by several of the new compounds. Several others are capable of forming unusually stable and interesting binuclear iron(II) complexes.     

Determination of Ephedrine via the Formation of Metal Complexes

Abstract

The reaction of ephedrine with carbon disulphide and metals'reagents (nickel, copper and cobalt has been studied. Various methods are accordingly introduced for the determination of ephedrine in pure form and in pharmaceutical formulations. Direct spectrophotometric method determines 0.24-1.21, 0.61-5.45 and 6.05-60.5 μ moles. of epherdrine with a mean accuracy (P'=0.05) of 100.24± 1.48%,99.65±1.68% and 99.73±0.59% using nickel, copper and cobalt respectively. Indirect determinations- through the metals' content- include atomic absorption method, which is suitable for the determination of 0.73-8.5, 1.82-6.66 and 3.63-24.2 μ moles. of ephedrine with a mean accuracy of 99.49±1.18%, 100.13±1.65% and 99.68±0.63% on using nickel, copper and cobalt respectively. The corresponding data on determining the metals by the oxalyldrazide method are : 1.45-16.94, 0.61-1.57 and 0.73-17.54 μ moles. of epherdrine, 99.13±0.6%, 99.35±0.71% and 99.54±0.73% on using nickel, copper and cobalt respectively.     

Gravimetric determination of cobalt and nickel,and their separations from copper with n-benzoylphenylhydroxylamine

N-Benzoylphenylhydroxylamine can be used for the gravimetric determination of cobalt and nickel. The precipitates can be weighed as such, or ignited and weighed as cobalt sulphate or nickclous oxide. Cobalt or nickel can be separated from copper with the reagent.     

Simultaneous spectrophotometric determination of cobalt,copper and nickel using 1-（2-thiazolylazo）-2-naphthol by chemometrics methods

The simultaneous determination of cobalt, copper and nickel using 1-（2-thiazolylazo）-2-naphthol （first figure of this article） by spectrophotometric method is a difficult problem in analytical chemistry, due to spectral interferences. By multivariate calibration methods, such as partial least squares （PLS） regression, it is possible to obtain a model adjusted to the concentration values of the mixtures used in the calibration range. Orthogonal signal correction （OSC） is a preprocessing technique used for removing the information unrelated to the target variables based on constrained principal component analysis. OSC is a suitable preprocessing method for PLS calibration of mixtures without loss of prediction capacity using spectrophotometric method. In this study, the calibration model is based on absorption spectra in the 550-750-nm range for 21 different mixtures of cobalt, copper and nickel. Calibration matrices were formed from samples containing 0.05-1.05, 0.05-1.30 and 0.05-0.80 μg·mL^-1 for cobalt, copper and nickel, respectively. The root mean square error of prediction （RMSEP） for cobalt, copper and nickel with OSC and without OSC were 0.007, 0.008, 0.011 and 0.031,0.037, 0.032 μg· mL^-1, respectively. This procedure allows the simultaneous determination of cobalt, copper and nickel in synthetic and real samples and good reliability of the determination was proved.     

Electrochemical synthesis,magnetic, spectral and cyclic voltammetric studies on lactic acid complexes

Summary Complexes of iron, cobalt, nickel and copper with lactic acid (H₂LA) were prepared by electrochemical oxidation of the metal in non-aqueous solution; this new method gives a high yield (73–87%). The reaction mechanism and the electrochemical efficiency show that cobalt, nickel and copper give divalent complexes and the iron complex is trivalent. The isolated complexes were characterized by physicochemical techniques. C.v.s of the complexes indicate the irreversibility of the electrode processes and confirm the oxidation state of the metals.     

Determination of copper,nickel, cobalt,silver, lead,cadmium, and mercury ions in water by solid-phase extraction and the RP-HPLC with UV-Vis detection

A new method for the simultaneous determination of seven heavy metal ions in water by solid-phase extraction and reversed-phase high-performance liquid chromatography (RP-HPLC) was developed. The copper, nickel, cobalt, silver, lead, cadmium, and mercury ions were pre-column derivatized with tetra( m-aminophenyl)porphyrin (T m-APP) to form colored chelates. The metal-T m-APP chelates in 100 mL of sample were preconcentrated to 1 mL by solid-phase extraction with a C(18 )cartridge; an enrichment factor of 100 was achieved. The chelates were separated on a Waters Xterra()RP(18) column by gradient elution with methanol (containing 0.05 mol L(-1) pyrrolidine-acetic acid buffer salt, pH 10.0) and acetone (containing 0.05 mol L(-1) pyrrolidine-acetic acid buffer salt, pH 10.0) as mobile phase at a flow rate of 1.0 mL min(-1) and detected with a photodiode array detector. The detection limits of copper, cobalt, nickel, silver, lead, cadmium, and mercury are 2, 2, 3, 4, 3, 3, and 3 ng L(-1), respectively, in the original sample. The method was also applied to the determination of these metals in water with good results.     

Chemical analysis of manganese nodules: Part IV. Determination of Nickel after Anion-exchange Separation

A method is described for the a.a.s. determination of nickel in manganese nodules after its separation from interfering metals. After dissolution of the sample in a mixture of perchloric and hydrofluoric acids, manganese, iron, cobalt, copper and other elements are adsorbed on the strongly basic anion exchange resin Dowex 1 (chloride form) from 95% ethanol-5% 12 M hydrochloric acid. The nickel passes into the effluent in which it is determined by a.a.s. with an air-acetylene flame. The method was used successfully for the determination of nickel in numerous samples of nodules from the Pacific Ocean.     

ICP-AES法测定红土镍矿中镍、钙、钛、锰、铜、钴、铬、锌与磷的含量

建立了ICP-AES法测定红土镍矿中Ni;Ca;Ti;Mn;Cu;Co;Cr;Zn和P含量的方法。样品用HCl、HNO3溶解,加入HF和HClO4,加热至HClO4烟冒尽,用HCl溶解盐类,过滤,采用ICP-AES法同时测定滤液中Ni、Ca、Mn、Cu、Co、Zn、P;残渣经灼烧、挥硅、K2S2O7熔融、HCl浸取,所得溶液与滤液合并,测定溶液中Cr和Ti含量。方法检出限:P为0.022μg/mL,其它元素在0.0032～0.0085μg/mL之间,方法的精密度(n=7)在1.4%～2.9%之间。分析结果与分光光度法、XRF法和AAS法分析结果的相对误差:Ni、Cu、Co、Cr小于5%,Ti和Mn小于10%,Zn小于15%,Ca和P小于19%。     

Simultaneous voltammetric determination of cobalt, nickel and labile zinc, using 2-quinolinethiol in the presence of surfactants without prior digestion

2-Quinolinethiol forms very stable cobalt and nickel complexes, which are strongly chemisorbed on the hanging mercury drop electrode (HMDE). This allows the simultaneous determination of cobalt, nickel and labile zinc traces; Co and Ni by differential pulse adsorptive stripping voltammetry (DPAdSV) and Zn by differential pulse sweep voltammetry (DPSV), even in the presence of a large amount of surfactant like Triton X-100. This is advantageous for determining these metals directly in natural waters, without previous UV-irradiation or acid digestion. The surfactant does not only not interfere, but shows a beneficial effect with respect to the resolution between copper and nickel peaks. The method has been tested in estuary waters. The determination limits are 1 nmol/l Ni, 10 nmol/l Co and 1 mol/l Zn, with RSD less than 6.3%.     

Stable free-radical complexing reagents in applications of electron spin resonance to the determination of metals: Part 2. Spin-labelled iminooxime [1]

Possibilities for the determination of metals by means of the intensity of the e.s.r. signal of the chelate-fonning reagent, spin-labelled iminomonoxime — 4-oximinomethyl-2,2,5,5-tetramethyl-3-imidazoline-1-oxyl, have been studied. The dissociation constant of the oxime group (pK^T_a = 9.36 ± 0.08) and the reagent partition constant in the chloroform—water system (log K_D = 0.80 ± 0.11) are reported. The reagent extracts copper, cobalt and nickel into chloroform. Copper is extracted as its CuA₂, chelate (log K_D = 0.91 ± 0.03; log K_ex = -3.35 ± 0.09; log β₂, = 15.8 ± 0.2). Several properties of the spin-labelled and conventional oximes are compared. It is confirmed that a radical-containing substituent produces a strong electron-acceptor effect. Unusual extractive and e.s.r.- spectroscopic behaviour of cobalt is indicated; an adduct of the spin-labelled chelate with atmospheric oxygen seems to be formed. Methods for the determination of cobalt and nickel based on the extraction with spin-labelled oxime into chloroform and subsequent separation of the excess of reagent on a chromatographic column are described. The detection limits are 3 × 10^-7 M for cobalt and 10^-6 M for nickel.