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.     

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 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.     

Analytical applications of azoisoxazoles. III. Complexes of cobalt,copper, and cadmium with 2-(5′-methyl-2′-isoxazolylazo)-4-methoxyphenol

2-(5′-methyl-2′-isoxazolylazo)-4-Methoxyphenol has been synthesized and its ionization constant (pK_a = 7.98 ± 0.08) spectrophotometrically determined in a 4% ($\text{v}\text{v}$) ethanol-water medium at μ = 0.25 M (NaClO₄). The reagent originates water soluble complexes with cobalt (log β₂ = 11.45 ± 0.16), copper (log β₁ = 7.15 ± 0.10), and cadmium (log β₁ = 3.96 ± 0.12), and can be used for the spectrophotometric determination of cobalt and copper as well as metallochromic indicator for copper.     

Determination of Microgram Amounts of Copper by Peak Paper Chromatography

Abstract

A chromatographic method has been developed for determining 1.00 to 6.00 μg 1^?1 of copper. The test solution (1 μ1) was applied to paper impregnated with 0.1% phthalate salt of aniline and p-dimethylaminobenzaldehyde (p-DAB) based schiff's base solution and the chromatogram was developed with methanol, then immersed in aqueous 5% solution of potassium ferrocyanide for 35. The heights of the reddish brown peak shaped zones produced were related to concentration of copper. Equal amounts of silver, nickel and cobalt did not interfere. The error was ≤±0.20 with standard deviation 0.105.     

Simultaneous Determination of Nickel and cobalt in Manganese Sulphate Electrolyte by DMGH2-Sensitized Differential Pulse Polarography

Abstract

A method is described for the simultaneous determination of nickel and cobalt in manganese sulphate electrolyte by the dimethylglyoxime (DMGH₂) sensitized differential pulse polarography. The high manganese sulphate background (1.2M) in the concentrated process plant electrolyte interferes only with the nickel determination and precludes its direct determination. A 50% v/v dilution and an excessive amount (2 × 10^?3M) of the chelating agent are required at pH7.7 for the reliable determination of both elements. Under these conditions, the linear concentration ranges are 0-110 μg/1 for nickel and 0-140 μg/1 for cobalt. The minimum detectable amounts above the levels present in the process plant electrolyte are 2 μg/1 and 1 μg/1 for both elements, respectively. The relative standard deviations for all measurements are between 1 and 3%.     

Evaluation and Application of the Internal Standard Technique for the Direct Determination of Copper in Fruit Juices Employing Fast Sequential Flame Atomic Absorption Spectrometry

Abstract

The present paper describes the evaluation and application of internal standard for the determination of copper in fruit juices, employing Fast Sequential Flame Atomic Absorption Spectrometry (FS FAAS). The internal standards tested were indium, cobalt, and nickel using correlation graphs. However, indium was used, considering the composition of the samples. After this step, copper was determined in fruit juices using indium as internal standard. This method allows the determination of copper with a limit of quantification of 0.011 mg L^?1. The fruit juice samples selected for analysis were of grape, orange, pineapple, peach, cashew, and strawberry. The contents of copper in these samples varied from 0.02 to 0.42 mg L^?1. The analytical results were compared with the results obtained by analysis of these samples after complete mineralization using acid digestion and determination employing FS FAAS. The statistical comparison by a t-test (95% confidence level) showed no significant difference between the results. The relative standard deviations (RSD) with and without the use of the internal standard for a copper solution containing 0.4 mg L^?1 were of 0.62 and 1.94%, respectively. The use of indium as internal standard provided more accurate analytical results, as well as better analytical performance for the determination of copper in juice samples.     

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.     

Optimization and validation of an automated voltammetric stripping technique for ultratrace metal analysis

A new automated batch method for the determination of ultratrace metals (nanogram per liter level) was developed and validated. Instrumental and chemical parameters affecting the performance of the method were carefully assessed and optimized. A wide range of voltammetric methods under different chemical conditions were tested. Cadmium, lead and copper were determined by anodic stripping voltammetry (ASV), while nickel, cobalt, rhodium and uranium by adsorptive cathodic stripping voltammetry (AdCSV). The figures of merit of all of these methods were determined: very good precision and accuracy were achieved, e.g. relative percentage standard deviation in the 4-13% for ASV and 2-5% for AdCSV.The stripping methods were applied to the determination of cadmium, lead, copper, nickel, cobalt, rhodium and uranium in lake water samples and the results were found to be comparable with ICP-MS data.     

Pre-concentration of ultra trace amounts of copper,zinc, cobalt and nickel in environmental water samples using modified C18 extraction disks and determination by inductively coupled plasma–optical emission spectrometry

A highly sensitive and accurate method for pre-concentration and determination of ultra trace amounts of zinc, copper, cobalt and nickel ions in environmental water samples is proposed. The method is based on the solid phase extraction of these ions on C18-bonded silica extraction disks modified with a novel Schiff base 2,2′-[1,6-hexanediyl bis (nitriloethylidine)]bis-1-naphthol (HDN). The retained ions on the prepared solid phase was eluted with 10 mL 0.01 M nitric acid and measured by inductively coupled plasma–optical emission spectrometry. The extraction efficiency and the influence of the type and least amount of eluent for the stripping of ions from the disks, pH, flow rates of sample solution and eluent, amount of HDN, effect of other ions and breakthrough volume were evaluated. The limits of detection of the method were 0.2, 0.2, 0.8 and 0.6 µg L^?1 for zinc, copper, cobalt and nickel, respectively and an enrichment factor of 100 was obtained. The proposed method was applied for determination of zinc, copper, cobalt and nickel ions in some natural and synthetic water samples with satisfactory results.     

The Application of A Three Dimensional Calibration Model to Nickel Determination in Copper - Based Materials

Abstract

The interferences in the determination of Ni by flame atomic absorption spectrometry due to the presence of copper and fluoboric acid have been studied according to a previously proposed calibration method ¹ that allows the investigation and quantification of the matrix effect. The ability of traditional calibration methods, like standard addition (SAM) or direct calibration approach, to overcome matrix effects has been studied. Such investigations have shown that direct calibration could provide as far as a -42% error in nickel determination, whereas SAM error could be about +17%. However this large error could be decreased to ±2% when the mathematical model here proposed is applied.

Once the method is verified to be able to solve matrix effects, it was applied to the determination of nickel in a real sample of copper fluoborate. The theory of experimental design was set as an useful tool in order to study matrix effects.     

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.     

Photothermal Deflection Spectroscopy for Ultra Trace Analysis of Cobalt and Copper Ions

Abstract

Photothermal deflection spectroscopy (PDS) is applied for the absolute determination at room temperature of ultra trace concentration of cobalt and copper ions in aqueous solution. The samples have been prepared by percolating 2 liters of solution prepared from Merck Titrisol Standards in 200 mg Merck-I cationic exchange resin. With the present experimental conditions the detection limit is 20 ppb and 200 ppb for copper and cobalt ions respectively within an overall accuracy of 5%. The response of the spectrometer has been calibrated using ICP technique.     

Spectrophotometric Determination of Some Pharmaceutically Active Amides and Imides

Abstract

The determination of nicotinamide, alloxan, saccharin, barbitone and theobromine is achieved by a simple and rapid spectrophotometric method. The proposed method depends on the bromine oxidation of the amide or imide functional groups with the formation of N - bromoamide or N - bromoimide respectively, having a positive bromine atom. The oxidation products oxidize iodide ions to iodine which is measured as its starch complex.

The method is suitable for the determination of : 0.08–0.4, 0.5–5, 20–80, 25–200 and 50–400 mg with a mean accuracy (P′ = 0.05) of 99.29 ± 1.39%, 101.36 ± 1.44 %, 101.28 ± 1.85 %, 99.94 ± 1.24 % and 100.82 ± 1.29 % for the mentioned compounds respectively.     

HPLC Determination of Ochratoxin A in a Low Volume of Human Blood Serum

Abstract

A high‐performance liquid chromatography (HPLC) method has been developed for the determination of ochratoxin A (OTA) in human blood serum. Samples were purified on a C18 solid phase extraction column. The developed method required a relatively low serum volume (0.5 ml). Significant correlation (r of 0.998) was found over the range from 0.10 to 8 ng/ml, with a detection limit of 0.1 ng/ml and better performance in terms of precision and accuracy. Mean recoveries at 0.5 and 2 ng/ml were respectively 69.7±1.2 and 71.9±2.8%. This method was used as a rapid and noninvasive tool to assess human exposure to OTA. Among 40 analyzed serum samples, 27.5% were found to contain OTA with levels going from 0.1 to 11.98 ng/ml with a mean concentration of 0.73±2.35 ng/ml.     

The determination of sulphur in copper,nickel and aluminium alloys by proton activation analysis

The ³⁴S(p, n)^34mCl reaction induced by 13-MeV protons is used for the determination of sulphur in copper, nickel and aluminium alloys. The ^34mCl is separated by repeated precipitation as silver chloride. The results obtained were 3.08 ± 0.47, 1.47 ± 0.17 and <1μg g^-1 for copper, nickel and aluminium alloys, respectively.     

Solid-phase extraction and simultaneous spectrophotometric determination of trace amounts of Co, Ni and Cu using partial least squares regression

A novel sensitive and simple method for rapid extraction, preconcentration and determination of cobalt, nickel and copper as their 1-(2-pyridilazo)-2-naphthol (PAN) complexes using polytetrafluoroethylene filter as solid phase and multivariate calibration of spectrophotometric data is presented. The analytical wavelengths of 400-700 nm were chosen and the experimental calibration matrix for partial least squares (PLS) was designed with 21 samples of 5.90-41.25, 0.30-29.35 and 0.64-41.30 ng ml⁻¹ for cobalt, nickel and copper, respectively. The cross-validation method was used for selecting the number of components. The root-mean-square errors of predictions (RMSEPs) were between 0.48 and 1.37 ng ml⁻¹. In this work we could reach preconcentration factors of 100 or even higher by using polytetrafluoroethylene as solid phase which is cheap and can be used in a wide range of pH, flow rates and for many times. The proposed method was successfully applied to the simultaneous determination of Co, Ni and Cu in tap and pit water samples.     

Starch coated titanium dioxide nanoparticles as a challenging sorbent to separate and preconcentrate some heavy metals using graphite furnace atomic absorption spectrometry

In this study, a challenging nanosorbent was described for preconcentration/separation method based on the sorption of cadmium, cobalt, copper, nickel, lead on starch coated titanium dioxide nanoparticles and its analysis by graphite furnace atomic absorption spectrometry. Optimum conditions were investigated for quantitative sorption. By using the proposed technique, the analyte elements were determined in spiked tap-water samples in the range of 95% confidence level. Limit of detection (3δ) was 0.05, 0.28, 1.90, 3.10 and 0.11 µg/L (3σ, N = 10) for cadmium, cobalt, copper, nickel and lead, respectively. The optimised technique is fast, easy handled, simple and environmental friendly.     

Simultaneous Trace Determination of Nickel and Cobalt in Natural Waters by Differential Pulse Polarography

Abstract

A differential pulse polarographic method has been developed for the simultaneous low level determination of nickel and cobalt in the presence of furildioxime in natural waters. The nature of the electrode processes was studied with cyclic voltammetry. Limits of determination of 0.4 μg/L and 0.15 μg/L were achieved for nickel and cobalt respectively     

Simultaneous Determination of Nickel(II) and Cobalt(II) by Second-Derivative Spectrophotometry

4-(2-Pyridylazo) resorcinol, PAR, is shown to be useful for simultaneous determination of cobalt(II) and nickel(II) using second-derivative spectrophotometric method with controlled experimental parameters. This method allows the determination of 0.20-1.25 ppm of nickel(II) and 0.25-1.50 ppm of cobalt(II) in mixtures with good precision and accuracy. This method has advantages of simplicity, speed and requires no prior separations.