Spectrophotometric determination of cobalt as the orange cobalt-biacetylmonoxime 2-pyridylhydrazone complex

A spectrophotometric method for the determination of cobalt is described. The method is based on the formation of an orange color by reaction of cobalt(II) with biacetylmonoxime 2-pyridylhydrazone in basic solutions. The molar absorptivity at 480 nm is about 9.2 × 10³ liters mol⁻¹ cm⁻¹ (pH 10) and spectrophotometric sensitivity is 0.0062 μg Co cm⁻² for ABSORBANCE = 0.001.     

The spectrophotometric determination of palladium with 2,2'-diquinolylketone-2″-pyridylhydrazone

Summary A method for the spectrophotometric determination of traces of palladium with 2,2'-diquinolylketone-2"-pyridylhydrazone is described. Experimental parameters were evaluated and a study of diverse ion tolerance carried out. Beer's law was obeyed and the molar absorptivity at 624 nm was 1.95×10⁴.

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Spektrophotometrische Palladiumbestimmung mit 2,2-Dichinolylketon-2 -Pyridylhydrazon

Zusammenfassung Die spektrophotometrische Bestimmung von Palladiumspuren mit 2,2'-Dichinolylketon-2"-Pyridylhydrazon wurde beschrieben. Die experimentellen Parameter wurden angegeben. Die Toleranz der Methode gegenüber verschiedenen Fremdionen wurde bestimmt. Das Beersche Gesetz ist gültig; die molare Extinktion beträgt 1,95×10⁴ bei 624 nm.

     

Colorimetric determination of palladium with pyridine-2-aldehyde-2'-pyridylhydrazone

The colorimetric determination of palladium described involves the extraction of chloro(PAP)palladium(II) from an acidic aqueous solution into o-dichlorobenzene and measurement of the absorbance of the extract solution. The method is suitable for the determination of 10–100 μg of palladium. Tolerance amounts for many metals have been determined and compare very favourably with those of other methods.     

Spectro photometric determination of cobalt(ii) with 2,2'-dipyridyl-2-pyridylhydrazone

A spectrophotometric study of the cobalt(II) complex of a new reagent, 2,2'-dipyridyl-2-pyridylhydrazone (DPPH) is presented. A water-soluble yellow-orange complex is formed in the pH range 3–11, and shows maximal absorbance at 480 nm with a molar absorptivity of 3.2·10⁴ l mol^-1 cm^-1 ; Beer's law is obeyed over the range 0.25–3.75 p.p.m. of cobalt. This complex is very stable and on addition of perchloric acid only a bathochromic shift takes place from 480 nm to 500 nm. This complex is stable even in the presence of 20% perchloric acid and shows a molar absorptivity of 4.2 ·10⁴ l mol^-1 cm^-1 ; Beer's law is obeyed over the range 0.15–2.00 p.p.m. of cobalt. A new method of determining trace amounts of cobalt is proposed, which possesses the advantages of high sensitivity and very high selectivity.     

Sorption of nickel and cobalt ions onto cobalt and nickel ferrites

The corrosion of the metal parts in the primary circuit of pressurized water reactors leads to the release of colloidal particles (NiFe(2)O(4), CoFe(2)O(4), NiO, Ni...) and ionic species (Co, Ni, Cr...). Particles can interact with ionic species in the primary medium, contributing to their transport and to their deposition onto surfaces outside the neutron flux generating radioactive contamination. Sorption and zetametry experiments at 25 °C were performed on the Ni(2+)/CoFe(2)O(4) and Co(2+)/NiFe(2)O(4) systems in order to determine the behaviour of corrosion products in the fluid of the primary circuit. Sorption appears as surface complexation starting from pH 6 and is followed by precipitation of hydroxide above pH 7.5. Complexation and solubility constants were obtained from the modelling of sorption curves. The two oxide systems present a very similar sorption behaviour, but some differences, due to their different isoelectric points, could be observed on zetametric measurements.     

Selective photometric determination of nickel with photochemically generated anti-2-furaldehyde 2-pyridylhydrazone

Summary Selective Photometric Determination of Nickel with Photochemically Generated Anti-2-Furaldehyde 2-Pyridylhydrazone A sensitive photometric determination of nickel, based on the formation of a coloured chelate with photochemically generatedanti-2-furaldehyde 2-pyridylhydrazone (anti-FAPH), is described. A detection limit of 3 ng/ml, sensitivity of 4 ng/ml and r. s. d. of 0.9% were found. The stoichiometry of the chelate was found to be 31 (LM) when thesyn-anti ratio in the photostationary state was taken into consideration. The influence of reaction variables, the effect of foreign ions, and applications of the technique to nickel determination in environmental fume samples and in aluminium-rich materials are described.     

Photometric determination of cobalt by means of photochemically generated anti-2-furaldehyde 2-pyridylhydrazone

The photochemical syn-anti isomerization of 2-furaldehyde 2-pyridylhydrazone (FAPH) in ethanolic solutions has been investigated. A study of the infrared, visible and ultraviolet, and n.m.r. spectra of the two isomers was made. The syn-anti ratio at the photostationary state was determined. syn-FAPH scarcely reacts with metal ions but the anti-FAPH formed by irradiation gives sensitive reactions with several metal ions to form stable chelates. A photometric method for the determination of cobalt (0.025-1.0 microg/ml ) in aqueous ethanolic medium (50% v/v ) at pH 9.7 is described. A detection limit of 0.007 microg/ml and relative standard deviation of 0.5% were found. By consideration of the syn-anti ratio at the photostationary state, the stoichiometry of the chelate was determined. An application of this technique to determination of cobalt in environmental fume samples is also described.     

Extraction spectrophotometric determination of cobalt and nickel using ethylthioxanthate

A spectrophotometric method for the determination of cobalt and nickel using a new reagent sodium ethylthioxanthate has been described. The yellow-colored cobalt complex and red-colored nickel complex have been extracted quantitatively using carbon tetrachloride in the pH ranges 4.0–11 and 4.0–6.7, respectively. The colors of these complexes are stable and absorbances have been measured at 389 nm for cobalt and 495 nm for the nickel complexes. Few ions interfere but the method has been applied successfully for the determination of these metal ions in various complex materials.     

Micellar colorimetric determination of iron, cobalt, nickel and copper using 1-nitroso-2-naphthol

1-Nitroso-2-naphthol, an excellent color-forming chelating agent, combines to Fe(III), Co(II), Ni(II), Cu(II) and so on to form slightly soluble complexes in aqueous solution. To determine these metal ions, a tedious and time consuming separation technique, such as liquid-liquid extraction, has often been performed. However, these metal-1-nitroso-2-naphthol complexes could be determined conveniently by ultraviolet-visible (UV-Vis) spectrophotometry in Tween 80 micellar medium that has polyoxyethylene groups. After conditions such as pH, the amount of 1-nitroso-2-naphthol and the stability were adjusted to their optimum values, the sensitivities of the metal ions in Tween 80 medium and in chloroform were compared. It was shown that the sensitivities of Fe(III) and Co(II) in Tween 80 medium were higher than in chloroform, but that of Cu(II) was lower. The interfering effects among analytes ions, Fe(III), Co(II), Ni(II) and Cu(II) were more serious than by other ions, but the interfering effects could be removed by adjusting pH or adding the masking agents such as NH(3) or oxalate. Detection limits of Fe(III), Co(II), Ni(II), and Cu(II) were 0.024, 0.016, 0.039 and 0.023 mug ml(-1), respectively, and the correlation coefficients of these calibration curves were above 0.996. Recovery yields of the metal ions in the mixed standard solution ranged from 96 to 103%, and their coefficients of variation were low ranging between 0.94 and 1.75%. Cu(II) in brass sample and the amount of Fe(III) in steel sample were also determined. This proposed technique is simple, convenient and speedy.     

Simultaneous determination of cobalt, nickel and palladium in micellar media using partial least square regression and direct orthogonal signal correction

A simple, novel and sensitive spectrophotometric method was described for the simultaneous determination of cobalt, nickel and palladium. The method is based on the complex formation of Co, Ni and Pd with 1-(2-pyridylazo)-2-naphtol (PAN) in Tween-80 micellar media. All factors affecting on the sensitivity were optimized and the linear dynamic range for determination of Co, Ni and Pd was found. The experimental calibration matrix was designed by measuring the absorbance over the range of 520-700 nm for 21 samples of 0.10-1.0, 0.050-0.50 and 0.050-4.0 microg ml(-1) of Co, Ni and Pd, respectively. The partial least square (PLS) modeling based on singular value decomposition (SVD) was used for the multivariate calibration of the spectrophotometric data. The direct orthogonal signal correction was used for pre-processing of data matrices and the prediction results of model, with and without using direct orthogonal signal correction, were statistically compared. The effects of various anions and cations on selectivity of the method were investigated. The proposed method was successfully applied to the determination of Co, Ni and Pd in water and alloy samples.     

Kinetic determination of cobalt by complexation with pyridine-2-aldehyde 2-pyridylhydrazone and ligand oxidation with bromate

Summary Kinetic Determination of Cobalt by Complexation with Pyridine-2-Aldehyde 2-Pyridylhydrazone and Ligand Oxidation with Bromate Optimum conditions for a kinetic procedure are outlined for the determination of cobalt. The rate of disappearance of pyridine-2-aldehyde 2-pyridylhydrazone (PAPH) in acidic medium is monitored spectrophotometrically at 372 nm. The method is based on the modification of the oxidation rate by complexation of PAPH with cobalt ions. The detection limit has been determined and the limitations to the sensitivity are discussed. A number of foreign ions have been tested for interference and the fundamental basis of their effects is discussed. The method has been used for determination of cobalt in soil samples.     

Flame atomic absorption spectrometric determination of trace amounts of palladium,gold and nickel after cloud point extraction

In this article, a sensitive cloud point extraction procedure for the preconcentration of trace amounts of palladium, gold and nickel prior to their determination by flame atomic absorption spectrometry has been developed. The cloud point extraction method is based on the complexation of Pd(II), Au(II), and Ni(II) ions with 1-(2-pyridylazo)-2-naphthol and entrapping in non-ionic surfactant Triton X-114. The main factors affecting cloud point extraction efficiency, such as pH of sample solution, concentration of 1-(2-pyridylazo)-2-naphthol and Triton X-114, equilibration temperature and time, were investigated in detail. Under the optimized conditions, calibration curves were constructed for the determination of palladium, gold and nickel according to the general procedure. Linearity was maintained from 0.01 to 1.0 μg/mL for palladium, 10.0 μg/mL to 1.5 μg/mL for gold, and 10.0 μg/mL to 0.5 μg/mL for nickel. Detection limits based on three times the standard deviation of the blank divided by the slope of analytical curve (3Sb/m) for Pd(II), Au(III), and Ni(11) ions were 3.4, 3.9, and 2.4 μg/mL, respectively. Seven replicate determination of a mixture of 0.5 μg/mL palladium and gold and 0.2 μg/mL nickel gave a mean absorbance of 0.174, 0.150, and 0.201 with relative standard deviation ±1.5, ±1.3, and ±1.8%, respectively. The high efficiency of cloud point extraction to carry out the determination of analytes in complex matrices was demonstrated. The proposed method has been applied for determination of trace amount of palladium, gold and nickel in certified reference material and water samples with satisfactory results.     

Coulometric determination of nickel and cobalt

A method has been developed for the successive determinations of nickel and cobalt by controlled potential coulomctric analysis with a. mercury cathode, using an aqueous pyridine electrolyte, Quantitles of the metals from about 10 to l00 mg per 100 ml are determinable with an average error of ±0.5 mg. Because this controlled potential electrolysis technique produces a clean separation of nickel and cobalt it can be used for preparing nickel-free cobalt compounds and cobalt-free nickel compounds.     

Removal of nickel and cobalt ions from aqueous solutions using electron-beam treatment

Radiation removal of Co²⁺ and Ni²⁺ ions from aqueous solutions containing Me²⁺ and various scavengers for OH radicals has been studied. In nondeaerated solutions containing HCOOK as OH radical scavenger, two mechanisms of removal were found: reduction leading to the insoluble colloidal metals and precipitation causing predominant formation of carbonate. The processes taking place are mainly affected by the concentration of formate scavenger and depend on the type of metal ions in solution.In the presence of aliphatic alcohols as OH radical scavengers at pH in the interval 6–8, the radiation treatment leads to the metallic product. The efficiency of reduction depends on the rate constant for the reaction of Me⁺ intermediate with corresponding alcohol radical.     

Spectrophotometric determination of palladium by solvent extraction as the Pd(II)-biacetylmonoxime 2-pyridylhydrazone complex

Determination of trace levels of palladium(II) is described. The method relies upon the extraction of palladium(II)-biacetylmonoxime 2-pyridylhydrazone (BMPH) from aqueous acidic solution into chloroform to form a purple-reddish complex. The molar absorptivity of the Pd-BMPH complex is about 7500 liters mol^?1 cm^?1 at 560 nm in the chloroform extract. The highly colored chloroform extract is suitable for spectrophotometric determination. The method devised has been applied to the determination of palladium in $\text{Pd}\text{CaCO}{}_3$ catalyst with good results.     

Use of 3-hydroxy-1,3-diphenyltriazine in the spectrophotometric determination of copper, palladium, iron, cobalt, nickel, and molybdenum

3-Hydroxy-1,3-diphenyltriazine (HDPTA) forms brightly coloured complexes with copper, palladium, iron, cobalt and nickel ions, which are readily extractable in benzene. The deep yellow molybdenum complex is completely soluble in 60% ethanol. All the chelates have a definite absorption maximum between 398 and 422 nm, the reagent absorption being negligible above 415 nm. The molar composition of the chelates is ML(2), except for iron and cobalt which form ML(3) complexes. Microquantities of these metals can be determined spectrophotometrically with HDPTA.     

An approach by using near-infrared diffuse reflectance spectroscopy and resin adsorption for the determination of copper, cobalt and nickel ions in dilute solution

Near-infrared spectroscopy (NIRS) has been proved to be a powerful analytical tool and used in various fields, it is seldom, however, used in the analysis of metal ions in solutions. A method for quantitative determination of metal ions in solution is developed by using resin adsorption and near-infrared diffuse reflectance spectroscopy (NIRDRS). The method makes use of the resin adsorption for gathering the analytes from a dilute solution, and then NIRDRS of the adsorbate is measured. Because both the information of the metal ions and their interaction with the functional group of resin can be reflected in the spectrum, quantitative determination is achieved by using multivariate calibration technique. Taking copper (Cu²⁺), cobalt (Co²⁺) and nickel (Ni²⁺) as the analyzing targets and D401 resin as the adsorbent, partial least squares (PLS) model is built from the NIRDRS of the adsorbates. The results show that the concentrations that can be quantitatively detected are as low as 1.00, 1.98 and 1.00 mg L⁻¹ for Cu²⁺, Co²⁺ and Ni²⁺, respectively, and the coexistent ions do not influence the determination.