Spectrophotometric Determination Of Co Research Articles

Simultaneous spectrophotometric determination of Co (II) and Co (III) in acidic medium with partial least squares regression and artificial neural networks

This study aims at the application of two chemometric techniques to visible spectra of acetic acid solutions of Co (II) and Co (III) for simultaneous determination thereof. Spectral data of 145 samples in the range of 400–700 nm were used to build the models. Partial least squares regression models were developed for which latent variables were determined using internal cross-validation with a leave-one-out strategy and 3 and 2 latent variables were selected for Co(II) and Co(III) based on root mean square error of cross-validation. For these models, root mean square errors of prediction were 1.16 and 0.536 mM and coefficients of determination were 0.975 and 0.892 for Co (II) and Co (III). As an alternate method, artificial neural networks consisting of three layers, with 10 neurons in hidden layer, were trained to model spectra and concentrations of cobalt species. Levenberg-Marquardt algorithm with feed-forward back-propagation learning resulted root mean square errors of prediction of 0.316 and 0.346 mM for Co (II) and Co (III) respectively and coefficients of determination were 0.996 and 0.988.

Design, spectral, molecular modeling, antimitotic, analytical and mechanism studies of phenyl isothiocyanate Girard's T derived metal complexes

The ligand N-{[(phenyl amino) thioxomethyl] hydrazino carbonyl methyl} trimethyl ammonium chloride (PTHAC) was prepared by the refluxing phenyl isothiocyanate and Girard-T (trimethyl ammonium-acethydrazide) in a molar ratio (1:1). The metal complexes derived from NiCl2.6H2O, CuCl2.2H2O and Co(CH3COO)2.6H2O were synthesized and purified. The PTHAC and its Cu(II), Co(II), and Ni(II) metal complexes(1–3) were characterized using a variety of various instrumental performances such as elemental analysis, magnetic moment, spectra (IR, UV–Vis, 1H NMR, mass) and thermal analysis (TGA and DTG).The results of element analysis, magnetic moment, spectra (IR, UV–Vis, 1H NMR, mass), and thermal (TGA and DTA) analyses provide the structures of the produced ligand and its (1–3) complexes. According to the spectroscopic results, PTHAC acts as an O, N and S tridentate donor, creating a mononuclear complex with copper(II), cobalt(II), and nickel(II) ions with an octahedral geometry. All of the atomic properties, including bond lengths, bond angles, HOMO, LUMO, dipole moments, and charges, have been determined. The cytotoxic activities of the PTHAC and the produced (1–3) complexes against breast carcinoma cells have been studied and correlated to the molecular modeling. When compared to the free ligand, CoII-L, and NiII-L, the CuII-L complex inhibits breast cancer cell growth more effectively. Furthermore, the PTHAC ligand was successfully applied for separation via flotation and spectrophotometric determination of Co(II) in several natural water, certified ore and pharmaceutical samples using oleic acid surfactant (HOL). At pH 6.5, PTHAC reacted with Co(II) to create a dark green (1:1) Co(II):PTHAC complex that was floated significantly using oleic acid (HOL) surfactant. The different experimental variable affecting the separation procedure e.g. pH, concentration of Co(II), HOL, PTHAC, temperature etc.…, were investigated. Co(II) had a linear range of (0.1–7.0) mgL−1. In the aqueous and scum layers, the molar absorptivities for the coloured complex are 0.14 × 104 and 0.16 × 105Lmol−1 cm−1, respectively. The LOD was 0.04 mgL−1, which is related to Sandell sensitivity of 3.7 × 10−3 µg cm−2 with a preconcentration factor of 200 and a RSD, % (n = 5) less than 4.2%. In addition, the mechanisms involved in the process of coordination of PTHAC with Cu(II), Co(II) and Ni(II) and the mechanism involved in the process of flotation of the PTHAC-Co(II) complex using HOL surfactant were elucidated.

Spectrophotometric determination of Co (II) in analytical sample using anew chromogenic reagent (PTMH)

At the current work, the substrate phenyl hydrazine reacted with selected thiophene-2-carbaldehyde in absolute ethanol and a few drops of glacial acetic acid to give 1-phenyl-2-(thiophen-2-ylmethylene)hydrazine (PTMH) as a selective and sensitive reagent. It was synthesized and studied to determine cobalt spectroscopy in the following detail: at a pH value of 6.0, which greatly increased the selectivity, Co(II) reacted with (PTMH) to form a 1:2 complexes, with absorption peaks at 386 nm for cobalt. Under the optimal conditions, Beers law was obeyed over the ranges of (0.14ـــ5.8) mg/L. The apparent molar absorptivity and Sandell’s sensitivities were 7.1360×104 L.mol-1.cm-1, and 8.2585×10-4 µg.cm-2. The detection limits were found to be 0.0133 and the limit of quantification is 0.0466.

Спектрофотометрическое определение ионовCo(II) сN-(2-гидроксибензоил)-N'-(п-тозил)гидразином в аммиачных средах

A technique has been developed for the spectrophotometric determination of Co(II) ions with N-(2-hydroxybenzoyl)-N'-(p-tosyl)hydrazine (GBSH) in an ammonia medium. The absorption spectra of the reagent and its complex with Co(II) ions have been recorded and analyzed. The optimal conditions for the formation of the complex compound were found: the pH range of complex formation; optimal time for color development; amount of photometric reagent. Under optimal conditions for the complexation of GBSG with Co(Ⅱ) ions, a calibration graph was constructed. The Bouguer-Lambert-Beer law is fulfilled in the range from 0.3 to 2.4 mg Co(II) in 25 ml of solution. The true and apparent molar light absorption coefficients were calculated. The true molar coefficient of light absorption of the complex compound GBSG with Co(Ⅱ) ions in an ammonia medium is 750. The molar ratios in the solution of the complex compound [Co(Ⅱ)]:[GBSG] = 1:1 and 1:2. The conditional stability constant of the GBSG complex with Co(Ⅱ) ions was calculated using the Babko method and it is 3.24∙1012. The convergence and correctness of the spectrophotometric technique were determined by the method of mathematical statistics.

Spectrophotometric Determination of Co(II) in Vitamin B12 Using2-(biphenyl-4-yl)-3-((2-(2,4-dinitrophenyl) hydrazono)methyl) imidazo [1,2-a]pyridine as Ligand by Flow Injection–Merging Zone Analysis

Nitro Schiff base ligand of 2-(biphenyl-4-yl)-3-((2-(2,4-dinitrophenyl) hydrazono) methyl) imidazo [1,2-a] pyridine (BDNHMIP) was synthesized, identified and used in spectrophotometric determination of Co(II) at 530nm. The suggested method of Co(II) determination was performed at optimum analytical parameters of 3.2 ml/min flow rate, 137.4L ligand volume, 98.1L Co(II) volume, 1minutes residence time in reaction coil, and as a result 48 sample/hour of method throughput was accomplished. The proposed method performed linearity of 25-400 ppm, molar absorptivity coefficient of 121.5704´103 L.mol.-1cm-1, and L.O.D of 2.28ppm. The suggested method was successful applied for determination of Co(II) content of vitamin B12 injection samples with high recovery of 99.5-100.3% and minimum relative error percent of -0.3 - 0.5%.

Cloud Point Extraction, Preconcentration and Spectrophotometric Determination of Co (II) and Cu (II) using 15-Crown-5

In the current study, a cloud point extraction (CPE) with UV-vis spectrometry for detection of Cu (II) and Co (II) ions with 15-crown-5 as a chelating agent was developed to be more selective and sensitive. The CPE method is improving the analytical signal and permits the preconcentration of metals ions. After phase separation induced by change temperature to become higher more than the temperature of the cloud, the point is performed with centrifugation. The Co (II) and Cu (II) ions are determined in the enriched phase by UV-vis spectrometry. Several factors affecting the extraction efficiency were optimized, e.x. pH, the concentration of the chelating agent, non-ionic surfactant concentrations, and cloud point temperature. Under optimum conditions, a linear calibration graph in the range of 0.5-5 ?g mL-1 of Co (II) in the initial solution with r2 = 0.9994 (n=8) and 0.2–7?g of Cu (II) in the initial solution (mL-1) with r2 = 0.9991 (n=8) were obtained. Detection limits of 0.4and 0.1?g are for Co(II) and Cu(II) along with preconcentration factors (66 and 50) for these ions, respectively. The method was used for detection of Co(II) and Cu(II) in some food samples.

Liquid-liquid extraction and simultaneously spectrophotometric determination of Co (II) and W (VI) using crown ether (DB-18-C6) in aqueous media and in high speed steel

ABSTRACT An analytical reagent ether crown DB-18-C-6 was extensively used for the simultaneous and individual extraction and spectrophotometric determination of the tungsten and cobalt at microgram levels. The ligand reacts with two metals, and the ion-association systems were extractable into chloroform giving a yellowish [(DB-18-C-6∙NH4)+ 2[WO(SCN)5]2] and [(DB-18-C-6∙NH4)+ 2[Co(SCN)4]2-] complexes. The absorption peaks of these complexes were found overlapping at λmax of 415 nm and 621.6 nm, respectively. Under optimum conditions, the [WO(SCN)4]2-] complexation and extraction are possible only in concentrated medium (2.5 M of HCl). While, the [Co(SCN)4]2-] was extractable at a pH range of 4–10. The linear ranges were 29.45–147.25 μg mL − 1 for Co(II) and 1.8–183 µg/mL for W(VI) with molar absorptivity, ε = 1.7 × 104 and ε = 1.6 × 104 dm3 mol−1 cm−1, respectively. The accuracy and reproducibility of the proposed method for various amounts of cobalt and tungsten in their binary mixture were tested, and the effects of diverse ions on their extraction were also investigated. The developed method was successfully applied for the simultaneous determination of Co(II) and W(VI) in high-speed steel (HS2-9-1-8) containing 2% W, 9% Mo, 1% V, and 8% Co.

Cloud Point Extraction, Preconcentration and Spectrophotometric Determination of Co (II) and Cu (II) using 15-Crown-5.

In the current study, a cloud point extraction (CPE) with UV-vis spectrometry for detection of Cu (II) and Co (II) ions with 15-crown-5 as a chelating agent was developed to be more selective and sensitive. The CPE method is improving the analytical signal and permits the preconcentration of metals ions. After phase separation induced by change temperature to become higher more than the temperature of the cloud, the point is performed with centrifugation. The Co (II) and Cu (II) ions are determined in the enriched phase by UV-vis spectrometry. Several factors affecting the extraction efficiency were optimized, e.x. pH, the concentration of the chelating agent, non-ionic surfactant concentrations, and cloud point temperature. Under optimum conditions, a linear calibration graph in the range of 0.5-5 ?g mL-1 of Co (II) in the initial solution with r2 = 0.9994 (n=8) and 0.2–7?g of Cu(II) in the initial solution (mL-1) with r2 = 0.9991 (n=8) were obtained. Detection limits of 0.4and 0.1?g are for Co(II) and Cu(II) along with preconcentration factors (66 and 50) for these ions, respectively. The method was used for detection of Co(II) and Cu(II) in some food samples.

A Green and Simple Technique for Flotation and Spectrophotometric Determination of Cobalt(II) in Pharmaceutical and Water Samples

In the present study, a green and simple technique has been used for the preconcentration , flotation and spectrophotometric detection of Co (II) in pharmaceutical and water samples is established. At pH 4, the chromogenic reagent 4-(2pyridyl azo) resorcinol (NaPAR) reacts with Co(II) to form a pink 1:2 (M:L) complex in aqueous solution. This complex has been successfully separated by flotation by the aid of the anionic surfactant, oleic acid(HOL). The concentration of Co(II) in the scum layer was determined easily by spectrophotometry at 510 nm. The parameters that influence the flotation and spectrophotometric determination of Co (II) were studied. Beer’s law was obeyed over a concentration range 0.01-0.32 µg ml-1 in the aqueous as well as in the scum layer. The molar absorptivity of the Co(II)-NaPAR in the aqueous and scum layer were found to be 1.2×104 L mol-1 cm-1and 1.54×105 L mol-1 cm-1, respectively. The detection limit of the proposed technique, the recovery % (R%) and the relative standard deviation(RSD%) are 3.09 ng ml-1, 98 % and 1.5%, respectively. The method was verified by analysis of real certified samples. The proposed procedure was applied to determine Co (II) in water, pharmaceutical samples as well as in synthetic mixtures. The mechanism of flotation is proposed.

Sensitive spectrophotometric determination of Co(II) using dispersive liquid-liquid micro-extraction method in soil samples.

Analytical performance of conventional spectrophotometer was developed by coupling of effective dispersive liquid-liquid micro-extraction method with spectrophotometric determination for ultra-trace determination of cobalt. The method was based on the formation of Co(II)-alpha-benzoin oxime complex and its extraction using a dispersive liquid-liquid micro-extraction technique. During the present work, several important variables such as pH, ligand concentration, amount and type of dispersive, and extracting solvent were optimized. It was found that the crucial factor for the Co(II)-alpha benzoin oxime complex formation is the pH of the alkaline alcoholic medium. Under the optimized condition, the calibration graph was linear in the ranges of 1.0-110 μg L(-1) with the detection limit (S/N = 3) of 0.5 μg L(-1). The preconcentration operation of 25 mL of sample gave enhancement factor of 75. The proposed method was applied for determination of Co(II) in soil samples.

New Analytical Technique for Determination of Trace Amount of Co (II) by Using a UV-Visible Spectrophotometric Method with Photometric Reagent

The compound 3-nitrosalicylaldehyde thiosemicarbazone (3-NSTS) is proposed as a new photometric reagent for the extractive spectrophotometric determination of Co (II). It reacts with Co (II) and form a stable colored complex in the pH range 5.5 to 6.5. This was well extracted in n-butanol. The absorption spectrum of Co (II): (3-NSTS) complex in n-butanol shows maximum absorbance at 460 nm. The system obeyed Beer's law up to 2–6 μg cm−3. The molar extinction coefficient was found to be 8.846 × 103 L mol−1cm−1 and the sensitivity of the method as defined by Sandell's sensitivity was 6.688 × 10−3 μg cm−2. The Composition of the extracted species was determined by Job's continuous variation method, mole ratio method and slope ratio method and it was found to be 1:2. The proposed reagent is satisfactorily applied for the determination of trace amount of Co (II) from synthetic and commercial samples.

The Spectrophotometric Determination of Co(II) in Microbe Media

The spectrophotometric determination has been widely used by virtue of low investment, simple equipment, convenient operation and high accuracy. The study discussed the application of picramazochrom spectrophotometry to measure Co (II) in the bacterial culture media including LB, NA and TGY medium. The parameters of chromogenic reaction containing absorption wavelength, buffer solution volume, chromogenic reagent volume and developing time were optimized. Under optimum conditions, the calibration graph was linear in the concentration range of 0~1.5mg/L (r2=0.9991) for Co (II). The LB, NA and TGY medium prepared with standard order (pH 7.0~7.4) have obvious influences on the measurement of Co (II) under shaking conditions (37°C, 120rpm), and the influence rates up to 43.46%, 40.32% and 18.03%, respectively. After the pH value of these media being adjusted to between 5 and 6, the influence rates were interestingly controlled in 5%. This picramazochrom spectrophotometry can be successfully applied to determine the Co (II) concentration in microbe media.

Pre-concentration and spectrophotometric determination of Co(II) by adsorption of its (E)-N1-((1-thiophen- 2- yl) ethylidene) benzene-1,2-diamine complex on an alumina column

A simple method was developed for the pre-concentration of Co(II) based on the adsorption of its (E)-N1-((1-thiophen- 2- yl) ethylidene) benzene-1,2-diamine complex on a neutral alumina column. The influence of acidity, eluting agents, stability of the column, sample volume and interfering ions was investigated in details. The adsorbed complex could be eluted using environmentally benign polyethylene glycol (PEG 400) and the concentration of Co(II) was determined by visible spectrophotometry at a wavelength maximum of 636 nm. A detection limit of 6 µg/l could be achieved and the developed procedure was successfully applied for the determination of Co(II) in spiked water samples. The pre-concentration factor attainable for quantitative recovery (>96%) of Co(II) was 100 for a 1000 ml sample volume. Key words: Co(II), pre-concentration, alumina column, polyethylene glycol, (E)-N1-((1-thiophen-2-yl) ethylidene) benzene-1,2-diamines.

Simultaneous Spectrophotometric Determination of Co2+, Ni2+ and Cu2+ in Industrial Alloys Using Partial Least Squares Method

Spectrometric multicomponent analysis is a subject of great practical importance in the environmental, clinical, pharmaceutical and cultural heritage areas. Partial Least Squares (PLS) modeling based on SIMPLS algorithm was applied for the simultaneous spectrophotometric determination of Co(II), Ni(II) and Cu(II) with ammonium purpurate (murexide) as the complexing agent. An analytical wavelengths of (400 to 490) nm were chosen and an experimental calibration matrix for PLS was designed with 21 samples of (0.354 to 5.893) μg/mL, (0.352 to 5.869) μg/mL and (0.381 to 6.355) μg/mL for cobalt, nickel and copper, respectively. A leave one out cross-validation procedure was used for selecting the number of components using PRESS. The method was successfully applied to the simultaneous determination of these metals in industrial alloys. Keywords: PLS, Spectrophotometric, Murexide, Cobalt, Nickel, Copper

Synthesis of New Reagent 2,6‐Diacetylpyridine Bis‐4‐Phenyl‐3‐Thiosemicarbazone (2,6‐DAPBPTSC): Selective, Sensitive and Extractive Spectrophotometric Determination of Co(II) in Vegetable, Soil, Pharmaceutical and Alloy Samples

AbstractNew synthesized reagent 2,6‐diacetylpyridine bis‐4‐phenyl‐3‐thiosemicarbazone (2,6‐DAPBPTSC) is proposed as a sensitive and selective analytical reagent for the extractive spectrophotometric determination of cobalt(II). Cobalt(II) forms a reddish brown colored complex with 2,6‐DAPBPTSC, which is extracted into isoamylalcohol, under optimum conditions. The maximum absorption of the isoamylalcohol extract is measured at 400 nm. Beer's law is applied in the range 0.6‐6.0 ppm of cobalt(II). The molar absorptivity and Sandell's sensitivity of the complex is calculated as 2.2 × 104 L mol−1 cm−1 and 2.68 × 10−3 μg cm−2, respectively. An adequate linearity with a correlation coefficient value of 0.969 is obtained for the Co(II)‐2,6‐DAPBPTSC complex. The instability constant of the complex, calculated from Asmus' method is 3.75 × 10−4 The precision and accuracy of the method is checked with calculation of relative standard deviation (n = 5), 0.388 and the detection limit a value is 0.0028 μg mL−1. The method is successfully employed for the determination of cobalt(II) in real samples, such as vegetables, soil, water samples, standard alloy samples, and the performance of the present method was evaluated in terms of Student ‘t’ test and Variance ‘f’ test, which indicates the significance of the present method is an inter comparison of the experimental values, using atomic absorption spectrometer (AAS).

<b>Speciation and stability of methylene blue-metal-thiocyanate ion-association complexes</b>

With thiocyanate, zinc(II), cobalt(II) and copper(II) ions form stable anion, [M(SCN)4]2-. This anion in turn with methylene blue (MB+) forms ion-pair of the type MB2[M(SCN)4] and turns methylene blue to violet. The stoichiometry and stability constants of the ion-association complexes were determined using Benesi-Hildebrand method and the stoichiometry was confirmed by Job’s continuous variation method. The kinetics of formation of ternary complexes was studied using stopped-flow technique. The equilibrium studies showed that the stability of ternary complexes increased in the order Co(II) > Cu(II) > Zn(II) and the formation rate constants increased in the order, Cu(II) > Zn(II) > Co(II). The relative stabilities indicate that cobalt is preferred to other two metals in the speciation of ternary complexes comparable with similar complexes in biosystems. This study also provides a method for the spectrophotometric determination of Co(II) and Zn(II) ions at nanogram levels at 25 oC and an ionic strength of 0.15 M. KEY WORDS: Ion-association complex, Kinetics, Zinc, Cobalt, Methylene blue, Thiocyanate Bull. Chem. Soc. Ethiop. 2008, 22(1), 85-91.

Simultaneous Derivative Spectrophotometric Determination of Co(II), Cu(II) and Fe(II)

Simultaneous Derivative Spectrophotometric Determination of Co(II), Cu(II) and Fe(II)

Kinetic spectrophotometric determination of Co(II) ion by the oxidation of ponceau 4R by hydrogen peroxide

Anew, sensitive and simple kinetic method has been developed for the determination of traces of Co(II) ions based on their catalytic effect in the oxidation of trisodium-2-hydroxy-1-(4-sulphonato-1-naphthylazo)naphthalene-6,8-disulphonate (red artificial color Ponceau 4R) by hydrogen peroxide in borate buffer. The reaction was followed spectrophotometrically by tracing the oxidation product at 478.4 nm within 1 min after the initiation of the reaction. The optimum reaction conditions are: borate buffer (pH 10.50), Ponceau 4R (8 x10-6 mol/dm3), H2O2 (3 x10-2 mol/dm3) at 22 ?C. Following this procedure, Co(II) can be determined with a linear calibration graph up to 1.17 ng/cm3 and a detection limit of 0.20, based on the 3??criterion. The relative error ranges between 4.80-3.25 % for the concentration interval of Co(II) ions 1.76-17.61 ng/cm3. The effects of certain foreign ions on the reaction rate were determined for an assessment of the selectivity of the method. The method was applied for the determination of Co(II) in pharmaceutical samples.

Mean centering of ratio kinetic profiles as a novel spectrophotometric method for the simultaneous kinetic analysis of binary mixtures

In this paper, a new and very simple method was developed for the simultaneous determination of binary mixtures without prior separation steps. The method is based on the mean centering (MC) of ratio kinetic profiles. The mathematical explanation of the procedure is illustrated. In order to evaluate the applicability of the method a model data as well as an experimental data were tested. The results from experimental data relating to the simultaneous spectrophotometric determination of Co(II) and Ni(II) based on their complexation reactions with 1-(2′-pyridylazo)-2-naphthol (PAN) in micellar media were presented as a real model for resolution of the binary systems. The analytical characteristics of the method such as detection limit, accuracy, precision, relative standard deviation (R.S.D.) and relative standard error (R.S.E.) were calculated.

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 μg ml −1 for Co(II) and 0.05–1.50 μg ml −1 for Ni(II). The relative standard deviation (R.S.D.) for the simultaneous determination of 0.50 μg 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.