Organic Co-precipitation Research Articles

Preconcentration of Cd(II) and Cu(II) ions by coprecipitation without any carrier element in some food and water samples

A simple, rapid, sensitive and environmentally friendly separation and preconcentration procedure, based on the carrier element free coprecipitation (CEFC) of Cu(II) and Cd(II) ions by using an organic coprecipitant, 2-{[4-(4-fluorophenyl)-5-sulphanyl-4H-1,2,4-triazol-3-yl]methyl}-4-{[(4-fluorophenyl) methylene]amino}-5-(4-methylphenyl)-2,4-dihydro-3H-1,2,4-triazol-3-one (MEFMAT) was developed. The analyte ions were determined by flame atomic absorption spectrometric (FAAS) determinations. The optimum conditions for the coprecipitation process were investigated on several commonly tested experimental parameters such as pH of the solution, amount of MEFMAT, sample volume, standing time, centrifugation rate and time. The influences of some anions, cations and transition metals on the recoveries of analyte ions were also investigated, and no considerable interference was observed. The preconcentration factor was found to be 50. The detection limits for Cu(II) and Cd(II) ions based on the three times the standard deviation of the blanks ( N:10) were found to be 1.49 and 0.45 μg L − 1 , respectively. The relative standard deviations were found to be lower than 3.5% for both analyte ions. The method was validated by analyzing two certified reference materials (CRM-TMDW-500 Drinking Water and CRM-SA-C Sandy Soil C) and spike tests. The procedure was successfully applied to sea water and stream water as liquid samples and tobacco, hazelnut and black tea as solid samples.

A study of the separation, enrichment and determination of trace amounts of Hg2+ synchronously

A novel, simple and highly reliable method for the determination of trace amounts of mercury on a glassy carbon electrode (GCE) modified with a compound of crystal violet and multi-walled carbon nanotubes (CV+I−/MWCNTs) is reported. The principle of organic co-precipitation in solution was applied to the application of electrochemical analysis. First, the CV+/MWNTs modified electrode was immersed in solution with I−, CV+ and I− to form an ion association complex (CV+I−) as the carrier by the following reaction. Hg2+ was added into solution, where it reacted with I− to form HgI42−, then in the presence of CV+ an organic coprecipitator formed HgI42−·2CV+ by electrostatic adsorption. Finally, the HgI42−·2CV+ was adsorbed by the carrier CV+I− onto the surface of the modified electrode by the principle of organic co-precipitation. Meanwhile, trace mercury could be detected on the CV+I− and MWCNTs modified electrode (CV+I−/MWCNTs/GCE) by an electrochemical method. Therefore, preconcentration, separation and electrochemical detection of trace mercury were simultaneously and synchronously carried out. After optimization of the method, a linear response was obtained in the concentration range from 5.0 × 10−9 – 1.9 × 10−6 M, with a detection limit of 1.0 × 10−10 M. The modified electrode shows high selectivity, sensitivity and stability. This modified GCE does not present any significant interference from Cd2+, Cu2+, Ag+, Fe3+, Pb2+, Cr3+, Zn2+. No deterioration was observed in the electrode response during at least 3 weeks of successive measurements. The proposed method enables the separation, enrichment and electrochemical detection of trace mercury in aqueous solutions.

Electrochemical determination of copper(ii) using co-poly (cupferron and β-naphthol)/gold nanoparticles modified glassy carbon electrodes

A novel, simple and reliable method for the determination of trace copper on glassy carbon electrodes (GCEs) modified with co-poly(cupferron and β-naphthol)/gold nanoparticles (GNPs) is reported. The present work realized the application of principle of organic co-precipitation in solution into electrochemical analysis. First, the co-poly(cupferron and β-naphthol) was electrochemically deposited on the prepared GNPs/GCE by CV scanning in order to obtain co-poly(cupferron and β-naphthol)/GNPs/GCE. Then, the chelating ligand cupferron on the surface of the modified electrode and copper ion in the solution form the chelate complex (Cu(II)-Cpf), at the same time, the Cu(II)-Cpf was induced to be adsorbed by the carrier β-naphthol on the surface of the modified electrode by the principle of organic co-precipitation. Thus, the Cu2+ of the coprecipitated complexation can be detected at the co-poly(cupferron and β-naphthol)/GNPs/GCE. Therefore, preconcentration-separation and electrochemical detection of trace copper were simultaneously and synchronously carried through. After optimization, two linear responses were obtained in the concentration range from 9.0 × 10−10 to 4.5 × 10−8 M and 5.0 × 10−8 to 1.5 × 10−6 M, with a low detection limit of 5.0 × 10−11 M. This modified GCE does not present any significant interference from Cd2+, Ag+, Fe3+, Pb2+, Cr3+, Zn2+, NO3−, Cl−, SO42− and EDTA. No deterioration was observed in the electrode response during at least 3 weeks of successive measurements. And the modified electrode shows high selectivity, sensitivity and stability. The proposed method provides a new way for the separation, enrichment and electrochemical detection of trace copper ion.

In situ synthesis of orange rutile ceramic pigments by non-conventional methods

Different precursor-mixtures of orange Cr,Sb-TiO2 ceramic pigment have been obtained by non-conventional methods (heterogeneous ammonia coprecipitation, urea homogeneous coprecipitation, PECHINI polyester method and an original aqueous–organic coprecipitation method in water–diethylenglycol medium) in order to produce in situ the pigment through the ceramic body firing. The pigmenting performances of powders were appraised in two cases: (a) as ceramic pigment for glazed porcelain stoneware and (b) as ceramic inks for screen printing of porcelain stoneware. Samples were characterised by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), UV–vis-NIR spectroscopy by diffuse reflectance method, CIE-L*a*b* colour parameters, BET specific surface area and crystallite size measured by the Scherrer method. The colouring performance of raw powders obtained by non-conventional methods in glazed porcelain stoneware improves that of the ceramic samples fired at 1100°C used as reference. TEM observations indicate nanostructured powders with pigmenting performance depending on factors such as their specific surface area (BET), the crystalline phases detected by XRD (e.g. anatase–rutile presence) and their crystallite size (Scherrer measurements). Ammonia coprecipitated samples, both in water and in water–diethylenglycol medium without surfactant addition, or modified by the addition of sodium dodecyl sulphate as surfactant, stand out by their colouring performance.

A Novel Method for Speciation of Chromium: Coprecipitation Without Carrier Element by Using a Triazole Derivative

A coprecipitation method has been established for speciation of chromium(III) and chromium(VI) in real samples. The procedure is based on the coprecipitation of Cr(III), by using a new organic coprecipitant, 3-phenyl-4-o-hydroxybenzyl-idenamino-4,5-dihydro-1,2,4-triazole-5-one, without adding any carrier element. After reduction of Cr(VI) by concentrated H2SO4 and ethanol, the method was applied to the determination of total Cr. The level of Cr(VI) was calculated by the difference of total Cr and Cr(III) levels. For optimum recovery of Cr(III), different analytical factors such as pH, amount of coprecipitant, centrifugation rate and time, and effect of sample volume, were investigated. The influences of some anions, cations, and transition metals on the recoveries were also investigated, and no significant interferences were observed. The preconcentration factor was 100. The detection limit based on 3 times standard deviation (sigma) of the blank (n = 10) for Cr(III) was 0.50 microg/L. In order to evaluate the accuracy of the method, certified reference materials (CRM-TMDW-500 Drinking Water and National Institute of Standards and Technology Standard Reference Material 1573a Tomato Leaves) were analyzed, and the results obtained were in good agreement with certified values. The presented procedure was applied for Cr speciation in various solid and liquid samples with successful results.

Carrier element-free coprecipitation with 3-phenly-4-o-hydroxybenzylidenamino-4,5-dihydro-1,2,4-triazole-5-one for separation/preconcentration of Cr(III), Fe(III), Pb(II) and Zn(II) from aqueous solutions

A separation/preconcentration procedure, based on the coprecipitation of Cr 3+, Fe 3+, Pb 2+ and Zn 2+ ions using a new organic coprecipitant, 3-phenly-4-o-hydroxybenzylidenamino-4,5-dihydro-1,2,4-triazole-5-one (POHBAT) without adding any carrier element has been developed. The method, thus, has been called carrier element-free coprecipitation (CEFC). The resultant concentrated elements were determined by flame atomic absorption spectrometric determinations. The influences of some analytical parameters including pH of the solution, amount of the coprecipitant, standing time, centrifugation rate and time, sample volume and diverse ions were investigated on the quantitative recoveries of analyte ions. The validation of the present preconcentration procedure was performed by the analysis of two certified reference materials. The recoveries of understudy analytes were found in the range of 93–98%, while the detection limits were calculated in the range of 0.3–2.0 μg L −1. The precision of the method evaluated as relative standard deviation (R.S.D.), was in the range of 3–7% depend on the analytes. The proposed method was successfully applied to environmental samples for the determination of the analytes.

Carrier element-free coprecipitation (CEFC) method for the separation, preconcentration and speciation of chromium using an isatin derivative

A new, simple, rapid and sensitive separation, preconcentration and speciation procedure for chromium in environmental liquid and solid samples has been established. The present speciation procedure for Cr(III) and Cr(VI) is based on combination of carrier element-free coprecipitation (CEFC) and flame atomic absorption spectrometric (FAAS) determinations. In this method a newly synthesized organic coprecipitant, 5-chloro-3-[4-(trifluoromethoxy) phenylimino]indolin-2-one (CFMEPI), was used without adding any carrier element for coprecipitation of chromium(III). After reduction of chromium(VI) by concentrated H 2SO 4 and ethanol, the procedure was applied for the determination of total chromium. Chromium(VI) was calculated as the difference between the amount of total chromium and chromium(III). The optimum conditions for coprecipitation and speciation processes were investigated on several commonly tested experimental parameters, such as pH of the solution, amount of coprecipitant, sample volume, etc. No considerable interference was observed from the other investigated anions and cations, which may be found in natural water samples. The preconcentration factor was found to be 40. The detection limit for chromium(III) corresponding to three times the standard deviation of the blank ( N = 10) was found 0.7 μg L −1. The present procedure was successfully applied for speciation of chromium in several liquid and solid environmental samples. In order to support the accuracy of the method, the certified reference materials (CRM-TMDW-500 Drinking Water and CRM-SA-C Sandy Soil C) were analyzed, and standard APDC-MIBK liquid-liquid extraction method was performed. The results obtained were in good agreement with the certified values.

A new approach to separation and pre-concentration of some trace metals with co-precipitation method using a triazole

A new co-precipitation method was developed to separate and pre-concentrate Fe 3+, Cu 2+, Cr 3+, Zn 2+, and Pb 2+ ions using an organic co-precipitant, 3-benzyl-4- p-nitrobenzylidenamino-4,5-dihydro-1,2,4-triazole-5-on (BPNBAT) without adding any carrier element, following flame atomic absorption spectrometric (FAAS) determinations. Effect of some analytical conditions, such as pH of the solution, quantity of the co-precipitant, standing time, centrifugation rate and time, sample volume, and interference of concomitant ions were investigated over the recovery yields of the metal ions. The recoveries of the analyte ions were in the range of 95–102%. The detection limits, corresponding to three times the standard deviation of the blank, were found to be in the range of 0.3–2.0 μg L −1. The precision of the method, evaluated as the relative standard deviation (R.S.D.) obtained after analyzing a series of 10 replicates, was between 1.6% and 6.0% for the trace metal ions. The method was validated by analyzing two certified reference materials and spiked addition. The proposed procedure was applied for the trace metal ions in some environmental samples.

Historical changes in the concentrations of polycyclic aromatic hydrocarbons (PAHs) in Lake Peipsi sediments

The distribution of 11 individual polycyclic aromatic hydrocarbons (PAHs) was analysed in a (210)Pb dated sediment core from the deepest area of Lake Peipsi and in four surface sediment samples taken from littoral areas. According to the concentrations in the core three groups of PAHs may be distinguished: (1) relatively stable concentrations of PAHs within the whole studied time interval; (2) very low concentrations in sediments accumulated before intensive anthropogenic impact (from 19th century up to the 1920s) following a slight increase and (3) an overall increase in PAH concentrations since the 1920s up to the present. Comprehensive analysis of PAHs in the core and monitoring data obtained in the 1980s together with the lithology of sediments show that an increase of anthropogenically induced PAHs correlates well with the history of fuel consumption in Estonia and speaks about atmospheric long-distance transport of PAHs. The continuous increase of PAH concentrations since the 1920s do not support the earlier hypothesis about the dominating impact of the oil shale fired power plants near the lake, because their emissions decreased significantly in the 1990s. The concentration of PAHs in the deep lake core sample correlates well with the content of organic matter, indicating absorption and co-precipitation with plankton in the sediment.

Coprecipitation of Naphthol Azosulfonates with Organic Coprecipitants and Its Use in Flow-Injection Analysis

The coprecipitation of azo compounds based on 4-nitrophenyl- and 4-sulfophenyldiazonium naphthol sulfonates as their diphenylguanidinium ion-pair complexes with analogous compounds of naphthalene-2-sulfonic acid and 4-phenylsulfodiazonium is investigated. The optimization of the coprecipitation is considered based on the notions of the driving force of the cocrystallization of impurities. The optical characteristics of colored ion-pair complexes are measured. It is found that the water solubility is decreased most substantially for azosulfonates with hydrophobic nitro groups and with no more than two sulfo groups in different aromatic nuclei, which can lead to a decrease in the detection limit due to preconcentration by coprecipitation, which stimulates the thermodynamic flux of concentrate elution. Coprecipitation is combined with flow-injection analysis in the on-line mode, and new procedures are developed for determining naphthol sulfonates and related azo compounds with the detection limit equal to 0.003–0.006 mg/50 mL.

Magnetic and microwave properties of Sm1?xBa2Cu3+xO7?? superconductors at 4.2 K prepared by an organic carbonate coprecipitation route

Samples of Sm1Ba2Cu3O7−δ and Sm0.95Ba2Cu3.05O7−δ are prepared by a coprecipitation technique using organic carbonates in the presence of stable polymers. The electrical, magnetic, and microwave measurements have been carried out to characterize the materials. Both normal (Sm1Ba2Cu3O7−δ ) and copper-rich (Sm0.95Ba2Cu3.05O7−δ ) samples showed sharp superconducting transitions at 94 K. Lower and upper critical fields of the samples are estimated from magnetization measurements. The critical magnetization current density (J mc ) and pinning force density (F p ) of the samples are obtained from the magnetization hysteresis loop at 4.2 K for fields up to 5T. Superconducting parameters (H c (O),K GL,λ,ξ) are obtained by using the values of lower and upper critical magnetic fields. Microwave-induced d.c. voltage measurements indicated a smaller number of weak links for copper-rich samples. The enhancement of critical current density and the reduction of total number of weak links for copper-rich samples may be due to the increase in hole concentration caused by the partial replacement of Sm by Cu.

Spectrophotometric determination of molybdenum in sea water with 5-chloro-7-iodo-8-quinolinol

5-Chloro-7-iodo-8-quinolinol was used for the spectrophotometric determination of micro amount of molybdenum in sea water after the preconcentration with organic coprecipitant. Effect of pH on the coprecipitation of molybdenum in phenolphthalein was examined using 99Mo as a tracer. Recovery of molybdenum was about 93% between pH of 2 to 4. Because the concentration of molybdenum in sea water is too low, it is preferable to reduce the volume of water sample to about one fifth by evaporation. No loss of molybdenum was observed by evaporation with the presence of a small amount of nitric acid. On the basis of these results water sample was analyzed with following procedure: Add 4 ml of nitric acid to 1 l of filtered sea water and evaporate to about 200 ml. Add 1 ml of 1% oxineacetic acid solution to the solution. After the pH of the solution adjust to 4.0, add phenolphthalein-ethanol solution (0.3 g/5 ml) and allow to stand over night. Collect the precipitate and dissolve in 10 ml of hot nitric acid. Add 5 ml of 60% perchloric acid to the solution and decompose organic matter by heating. After the pH of the solution adjust to 1.0, dilute to 25 ml with water. Extract molybdenum with 10 ml of 2.5 × 10-3 M 5-chloro-7-iodo-8-quinolinol-CHCl3 solution. Measure the absorbance of CHCl3 solution at 392 nm against the reagent blank. The overall recovery of molybdenum from sea water was about 89%. The content of molybdenum in surface sea water in the Pacific near the Ogasawara Islands and Yoron Island were found to be 10.4 and 9.8μg/l, respectively.

Spectrophotometric determination of palladium after coprecipitation of its α-furildioxime chelate using naphthalene as an organic coprecipitant

Spectrophotometric determination of palladium after coprecipitation of its α-furildioxime chelate using naphthalene as an organic coprecipitant

Radioactivation analysis of aluminium, vanadium, copper, molybdenum, zinc and uranium in natural water samples using organic coprecipitants

A method is described for the determination of trace metal ions, V, Al, Cu, Mo Zn, and U, in natural water samples by neutron activation analysis, using organic coprecipitation as a preconcentration method. The preconcentration of trace elements was accomplished by converting the dissolved trace metal ions into the oxine chelates atpH 5.2 and extraction of the chelates witho-phenylphenol which is a liquid above 56 °C and solidifies at room temperature. After cooling the extraction system, the fine particles of the organic phase were collected on a millipore filter and the precipitate was air-dried in a clean environment. The solid extract was wrapped up in a sheet of clean polyethylene and subjected to neutron irradiation in a reactor for less than 10 min at a thermal flux of 2·1013 n·cm−2·sec−1. γ-Ray spectrometry by a coaxial Ge(Li) detector connected to a 1024-channel PHA was performed on the irradiated sample without further chemical separation, and thus the ppb level concentration of the elements in natural water samples could be determined. The fundamental study of the collection of the trace elements is also described.

The Coprecipitation and Spectrophotometric Determination of Iron as 8-Hydroxyquinolinate

Abstract The coprecipitation and spectrophotometric method, which is likened to the solvent extraction and spectrophotometric method, was applied to the following system for the first time; ferric ion was coprecipitated as 8-hydroxyquinolinate with an organic coprecipitant, and was determined spectrophotometrically after the precipitate was dissolved with an organic solvent. The effect of the ligand concentration on the pH vs. absorbance curve in the present method was apparently similar to that for solvent extraction. A nearly constant absorbance was obtained above pH 4 at a ligand concentration of 4×10−3 m. Over 100 mg of o-phenylphenol, an almost quantitative coprceipitation was obtained, though the absorbance decreased gradually as the coprecipitant was increased. The effect of diverse ions was also examined. Titanium(IV), vanadium(V) and molybdenum(VI) interfered considerably, while others have little effect on the absorbance. The method was applied to the determination of trace amounts of iron in natural waters and reagent grade sodium chloride.

Coprecipitation of microgram amounts of beryllium and thorium with organic reagents

Methods for coprecipitating microgram amounts of beryllium and thorium using organic coprecipitants are reported. The former is coprecipitated with méthylène blue and tannie acid at pH 8–10, while the latter is coprecipitated with methyl violet and SPADNS at pH 8.

速中性子による放射性同位体製造の研究, (III)

Preparation of 64Cu of high specific activity by the reaction 64Zn (n, p)64Cu was investigated. Five grams of zinc oxide were irradiated in JRR-1 reactor for 5 hr. 64Cu produced was separated from zinc by an anion exchange or the combination of organic co-precipitation and anion exchange. About 1 mc of 64Cu with specific activity of more than 2.5×106 mc/g Cu at best was prepared.The use of an orgnic co-precipitation was useful to reduce processing time.Some comparisons were made to a Szilard Chalmers process, which was the other method to prepare 64Cu of high specific activity.

Coprecipitation of Pu (IV) with organic coprecipitants

Coprecipitation of Pu (IV) with organic coprecipitants

Using radioactive isotopes in elaborating new methods in analytical chemistry: organic co-precipitants: V. I. Kuznetsov, U.S.S.R.

Using radioactive isotopes in elaborating new methods in analytical chemistry: organic co-precipitants: V. I. Kuznetsov, U.S.S.R.