Preconcentration of 1-(2-pyridylazo)-2-naphthol-iron(III)-capriquat on a membrane filter, and third-derivative spectrophotometric determination of iron(III)

Iron(III) was preconcentrated by collection on an organic solvent-soluble membrane filter (nitrocellulose (NC)) of the iron(III)-1-(2-pyridylazo)-2-naphthol (PAN) complex in the presence of capriquat as an oily quaternary ammonium salt. Third-derivative spectrophotometry was used for measurement of the third-derivative distance (d(3)A/dlambda(3)) between lambda(1) = 520 nm and lambda(2) = 590 nm or lambda(3) = 660 nm and lambda(4) = 724 nm of the iron(III)-PAN-capriquat complex or PAN-capriquat in dimethylsulfoxide (DMSO) following preconcentration. The calibration curve was linear in the range of 1-10 mug iron(III)/5.0 ml DMSO solution. The proposed method was about five-fold more sensitive and more selective than using zero-order spectrophotometry.     

Selective potentiometric determination of Bi(III) with a coated-wire electrode

A bismuth-selective electrode based on the chlorobismuthate(III) salt of Aliquat 336 is described. The electrode gives nearly linear response in the bismuth concentration range 10⁻¹–10⁻⁴M. The optimum solution conditions for operation of the electrode have been determined together with possible interference effects. The application of the electrode to analysis of samples containing large amounts of other metals is illustrated by the determination of bismuth in pharmaceuticals. The electrode is shown to give results by direct potentiometry and the standard-addition method which differ from atomic-absorption results by not more than 2%.     

Determination of Cu(III) and Cu(II) + Cu(III) in superconducting copper ceramics

Summary Copper(III) and total copper in superconducting Y-Ba-Cu oxide and related compounds can be determinated by two successive iodimetric titrations after the sample has been dissolved under Ar in HCl/KI medium. First, the iodine equivalent to copper(III) ist titrated with Na₂S₂O₃ solution at pH 4.8, copper(II) being masked with EDTA. The total copper is then determined in the same solution by demasking with acid and iodide, followed by iodimetric titration. The method is both accurate and reproducible. The relative standard deviations for 1.074% copper(III) and 23.37% total copper are 0.8% and 0.3%, respectively.     

Determination of oxygen stoichiometry in mixed Mn(III)/Cr(III)-oxides

Summary The method and experiences with the determination of oxygen Stoichiometry in mixed manganesechromium sesquioxides are described. The decomposition is carried out in sealed glass tubes in hydrochloric acid in presence of a ferro-ferric system. The oxydation state of the analysed materials is determined by titration of Fe²⁺ ions with a solution of cerium salt, ferroin being used as indicator.

---

Bestimmung der Sauerstoff-Stöchiometrie in Mn(III)/Cr(III)-Mischoxiden

Zusammenfassung Es werden ein Verfahren sowie Erfahrungen mit der Bestimmung des Sauerstoffüberschusses in Mangan(III)/Chrom(III)-Mischoxiden beschrieben. Die Proben werden in zugeschmolzenen Ampullen mit SalzsÄure in Gegenwart von Eisen(II/III)-ionen aufgelöst. Sauerstoffüberschu\ wird durch Titration von Fe(II) mit Cer(IV)-salz in Gegenwart von Ferroin als Indicator bestimmt.

     

Spectrophotometric study of 1,2,5,8-tetrahydroxyanthraquinone-In(III) complex: Determination of In (III)

The 1,2,5,8-tetrahydroxyanthraquinone (quinalizarin) forms a colored complex with the ion In(III) in dimethylformamide-water solution. The 3:1 (R:In(III)) complex shows a λ_max of 565 nm and a molar absorptivity of 4.59 × 10⁴ liters mol^?1 cm^?1. A new method for the spectrophotometric determination of In(III) between 0.2 and 2.2 ppm with a relative error of 1.57% is proposed.     

Volumetric titration of iron (III)-salts with disodium EDTA, using FeII-cacotheline as indicator

Summary A volumetric method has been developed for the determination of iron (III) with disodium EDTA, using a mixture of cacotheline and iron(II) as indicator. The titration of the iron (III) salt is carried out in a buffered solution ofph 4–5 in carbon dioxide atmosphere with magnetic stirring, until a pink color appears. The pink color is due to the reduction of cacotheline by ferrous-EDTA. The reduction occurs only when all the iron (III) is complexed by EDTA. The end point is sharp and the method has been found to give results accurate to±0.3 to±0.5 percent.     

Eu(III) and Tb(III) luminescence sensitized by thiophenyl-derivatized nitrobenzoato antennas

Thiophenyl-derivatized nitrobenzoic acid ligands have been evaluated as possible sensitizers of Eu(III) and Tb(III) luminescence. The resulting solution and solid-state species were isolated and characterized by luminescence spectroscopy and X-ray crystallography. The Eu(III) complex with 2-nitro-3-thiophen-3-yl-benzoic acid, 1, crystallizes in the monoclinic space group C2/c with a = 28.569(3) A, b = 17.7726(18) A, c = 17.7073(18) A, beta= 126.849(2) degrees, and V = 7194.6(13) A3. The Tb(III) complex with this ligand, 2, is isostructural, and its cell parameters are a = 29.755(6) A, b = 18.123(4) A, c = 19.519(4) A, beta= 130.35(3) degrees, and V = 8021(3) A3. Eu(III) crystallizes with 3-nitro-2-thiophen-3-yl-benzoic acid as a triclinic complex, 3, in the space group P1 with a = 11.045(2) A, b = 12.547(3) A, c = 15.500(3) A, alpha = 109.06(3)degrees, beta = 94.79(3) degrees, gamma = 107.72(3) degrees. and V = 1893.5(7) A3. With the ligand 5-nitro-2-thiophen-3-yl-benzoic acid, Eu(III) yields another molecular compound, 4, triclinic P1, with a = 10.649(2) A, b = 14.009(3) A, c = 15.205(3) A, alpha= 112.15(3) degrees, beta = 100.25(3) degrees, gamma = 106.96(3) degrees, and V = 1900.5(7) A3. All compounds dissolve in water and methanol, and the methanolic solutions are luminescent. The solution species have a metal ion-to-ligand ratio of 1:1. The quantum yields have been determined to be in the range of 0.9-3.1% for Eu(III) and 4.7-9.8% for Tb(III). The highest values of these correspond to the most intense luminescence reported for Ln(III) solutions with this type of sensitizer. The lifetimes of luminescence are in the range of 248.3-338.9 micros for Eu(III) and 208.6-724.9 micros for Tb(III). The stability constants are in the range of log 11 = 2.73-4.30 for Eu(III) and 3.34-4.18 for Tb(III) and, along with the energy migration pathways, are responsible for the reported efficiency of sensitization.     

Atomic absorption spectrometric determination of Fe(III) and Cr(III) in various samples after preconcentration by solid-phase extraction with pyridine-2-carbaldehyde thiosemicarbazone

An atomic absorption spectrometric method for the determination of Fe(III) and Cr(III) after solid-phase extraction of their Schiff-base chelates by a column procedure with Amberlite XAD-4 was developed. A Schiff base, pyridine-2-carbaldehyde thiosemicarbazone (PCTSC), was synthesized and used as a chromogenic reagent for solid-phase extraction of Fe(III) and Cr(III) ions in the column procedure. The influence of various analytical parameters including the amount of solid phase, pH, type of elution solution, volume of sample solution, and flow rate of sample solution on the extraction efficiency of analytes were investigated. The recoveries of Fe(III) and Cr(III) were 99 ± 1 and 98 ± 2%, respectively, at the 95% confidence level under the optimum conditions. Fe(III) and Cr(III) were preconcentrated up to 25-fold. The limit of detection of Fe(III) and Cr(III) are 4.1 and 3.72 μg/L, respectively. The proposed method was applied to the determination of these metal ions in tap water, river water, Atatürk Dam water, and alloy samples. The relative standard deviation and the relative error are lower than 6%. The text was submitted by the authors in English.     

Fluorimetric determination of iron(III) by a kinetic method

A sensitive and relatively interference-free method for the kinetic determination of iron(III) is described. The method is based on the catalytic action of this ion on the autoxidation process of 4,8-diamino-1,5-dihydroxyanthraquinone-2,6-disulfonate (disodium salt), to produce a strong pink fluorescence that increases with time. The reaction is monitored at 585 nm, when excited at 525 nm, and the initial rate method is applied to perform the analytical procedure. The influence of reaction variables and the effect of foreign ions are discussed. Iron(III) contents between 0.1 and 1 μg ml^?1 can be determined with R.S.D. of ± 3.7%.     

Spectrofluorimetric determination of Er (III) with diantipyrylmethane

The optimum fluorescence conditions for erbium (III) are obtained by irradiating this lanthanide at 435 nm in 0.04 microg ml(-1) diantipyrylmethane solution at pH = 8 (lambdaem = 510 nm). The method proposed is satisfactory for the determination of erbium (III) in the range of 0.001 to 1 microg ml(-1). The relative standard deviation 0.02 microg ml(-1) Er (III) in 0.04 microg ml(-1) diantipyrylmethane solution is 1.1%. The effect of other rare earths upon the intensity of the fluorescence emitted by erbium (III) is discussed.     

Efficiency and application of poly(acryldinitrophenylamidrazone-dinitroacrylphenylhydrazine) chelating fiber for pre-concentrating and separating trace Au(III), Ru(III), In(III), Bi(III), Zr(IV), V(V), Ga(III) and Ti(IV) from solution samples

Poly(acryldinitrophenylamidrazone-dinitroacrylphenylhydrazine) chelating fiber was synthesized from polyacrylonitrile fiber and used for enrichment and separation for traces of Au(III), Ru(III), In(III), Bi(III), Zr(IV), V(V), Ga(III) and Ti(IV) ions from solution samples. The acidity, rate, re-use, capacity and interference on the adsorption of ions on the chelating fiber as well as the conditions of desorption of these ions from the chelating fiber were investigated by means of inductively coupled plasma optical emission spectrometry. The results show that 10-100 ngml(-1) of Au(III), Ru(III), In(III), Bi(III), Zr(IV), V(V), Ga(III) and Ti(IV) ions can be quantitatively enriched by the chelating fiber at a 2 mlmin(-1) of flow rate in the range pH 4-5, and desorbed quantitatively with 20 ml of 5 M HCl for In(III), Bi(III), Zr(IV), V(V), Ga(III), Ti(IV) and 20 ml of 4 M HCl+2% CS(NH(2))(2) solution for Au(III), Ru(III) (with recovery>95%). 50- to 500- fold excesses of Fe(III), Al(III), Mg(II), Mn(II), Ca(II), Cu(II), Ni(II) ions cause little interference in the concentration and determination of analyzed ions. When the fiber was reused for 8 times, the recoveries of the above ions enriched by the fiber were still over 87%. The relative standard deviations (RSDs) for the enrichment and determination of 10 ngml(-1) Au, Ru, In, Bi, Ga and 1 ngml(-1) Zr, V, Ti were lower than 3.0%. The results obtained for these ions in real solution samples by this method were basically in agreement with the given values with average errors of less than 6.3%. FT-IR spectra show that existence of NNCNHNH, OCNHNH and NO(2) functional groups are verified in chelating fiber, and Au(III) or Ru(III) is mainly combined with nitrogen (or oxygen) of the groups to form a chelate complex.     

Reverse flow injection spectrophotometric determination of iron(III) using norfloxacin

A reversed flow injection colorimetric procedure for determining iron(III) at the μg level was proposed. It is based on the reaction between iron(III) with norfloxacin (NRF) in 0.07 mol l⁻¹ ammonium sulfate solution, resulting in an intense yellow complex with a suitable absorption at 435 nm. Optimum conditions for determining iron(III) were investigated by univariate method. The method involved injection of a 150 μl of 0.04% w/v colorimetric reagent solution into a merged streams of sample and/or standard solution containing iron(III) and 0.07 mol l⁻¹ ammonium sulfate in sulfuric acid (pH 3.5) solution which was then passed through a single bead string reactor. Subsequently the absorbance as peak height was monitored at 435 nm. Beer's law obeyed over the range of 0.2–1.4 μg ml⁻¹ iron(III). The method has been applied to the determination of total iron in water samples digested with HNO₃–H₂O₂ (1:9 v/v). Detection limit (3σ) was 0.01 μg ml⁻¹ the sample through of 86 h⁻¹ and the coefficient of variation of 1.77% (n=12) for 1 μg ml⁻¹ Fe(III) were achieved with the recovery of the spiked Fe(III) of 92.6–99.8%.     

Spectrophotometric Study of 1, 3-Cyclohexanedione Bisthiosemicarbazone Monohydrochloride -Bi (III) Complex. Determination of Bi (III)

Abstract

The spectrophotometric study was made of red-violet 1, 3-cyclohexanedione bis-thiosemicarbazone-Bi (III) in an acidic dimethylformamide-water solution (λ_max = 540 nm, ? = 3.3 × 10^?4 1. mol^?1. cm^?1, stoichiometry 3:1, apparent stability constant (6.0 × 10¹⁰). A new method for the spectrophotometric determination of Bi (III) is proposed for concentrations between 0.7 and 7.4 ppm. The relative error (95 % confidence level) is 0.5 % for 3.7 ppm of Bi (III).

The extraction with methyl isobutyl ketone of the red-violet complex was also studied spectrophotometrically (λ_max = 550 nm, ? = 3.34 × 10⁴ 1. mol^?1.cm^?1, stoichiometry 2:1). A new method for the extraction-spectrophotometric determination of Bi (III) is proposed for concentrations, in aqueous phase, between 0.2 and 1.2 ppm. The relative error (95 % confidence level) is 0.8 % for 0.9 ppm of Bi (III).     

Separation of gadolinium(III) and lanthanum(III) by nanofiltration-complexation in aqueous medium

A new method is proposed for the separation of gadolinium(III) and lanthanum(III) in aqueous medium by nanofiltration combined with a complexation step. First DTPA was chosen as ligand for a selective Gd(III)/La(III) complexation. Having investigated the influence of three factors (pH, temperature and amount of ligand) for the selective complexation of DTPA towards Gd(III) and La(III), the system is then combined with a nanofiltration separation process to remove 92% of initial Gd(III) and only 12% of initial La.     

Extraction separation of thallium (III) from thallium (I) with n-octylaniline

A novel method is developed for the extraction separation of thallium(III) from salicylate medium with n-octylaniline dissolved in toluene as an extractant. The optimum conditions have been determined by making a critical study of weak acid concentration, extractant concentration, period of equilibration and effect of solvent on the equilibria. The thallium (III) from the pregnant organic phase is stripped with acetate buffer solution (pH 4.7) and determined complexometrically with EDTA. The method affords the sequential separation of thallium(III) from thallium(I) and also commonly associated metal ions such as Al(III), Ga(III), In(III), Fe(III), Bi(III), Sb(III) and Pb(II). It is used for analysis of synthetic mixtures of associated metal ions and alloys. The method is highly selective, simple and reproducible. The reaction takes place at room temperature and requires 15-20 min for extraction and determination of thallium(III).     

A Coulometric Analysis Method and an Ion-exclusion Chromatographic Method for the Determination of Antimony(V) in Large Excess of Antimony(III)

A coulometric analysis method and an ion-exclusion chromatographic method were developed for the determination of antimony(V) in a large excess of antimony(III). Antimony(V) reacted with potassium iodide in a high concentration hydrochloric acid; the liberated iodine was determined by the standard-addition method using coulometrically generated iodine. Using a Dionex ICE-AS1 ion-exclusion column, antimony(V) was eluted with 40 mmol/L sulfuric acid; on the other hand, antimony(III) was strongly retained on the column. The content, expressed as the amount ratio of antimony(V) to antimony(III), was 0.035% in a 10 g/kg antimony(III) solution prepared from an antimony(III) oxide reagent by the coulometric analysis method and 0.036% in a 1 g/kg antimony(III) solution prepared from the same antimony(III) oxide by the ion-exclusion chromatographic method. The results of both methods were in good agreement with each other. The detection limit of antimony(V) in antimony(III) oxide by the former method was 0.004% of antimony(III), and that by the latter method was 0.002% of antimony(III).     

Aerobic catechol oxidation catalyzed by a bis(mu-oxo)dimanganese(III,III) complex via a manganese(II)-semiquinonate complex

A 3,5-di-tert-butyl-1,2-semiquinonato (DTBSQ) adduct of Mn(II) was prepared by a reaction between Mn(II)(TPA)Cl(2) (TPA = tris(pyridin-2-ylmethyl)amine) and DTBSQ anion and was isolated as a tetraphenylborate salt. The X-ray crystal structure revealed that the complex is formulated as a manganese(II)-semiquinonate complex [Mn(II)(TPA)(DTBSQ)](+) (1). The electronic spectra in solution also indicated the semiquinonate coordination to Mn. The exposure of 1 in acetonitrile to dioxygen afforded 3,5-di-tert-butyl-1,2-benzoquione and a bis(mu-oxo)dimanganese(III,III) complex [Mn(III)(2)(mu-oxo)(2)(TPA)(2)](2+) (2). The reaction of 2 with 3,5-di-tert-butylcatechol (DTBCH(2)) quantitatively afforded two equivalents of 1 under anaerobic conditions. The highly efficient catalytic oxidation of DTBCH(2) with dioxygen was achieved by combining the above two reactions, that is, by constructing a catalytic cycle involving both manganese complexes 1 and 2. It was revealed that dioxygen is reduced to water but not to hydrogen peroxide in the catalytic cycle.     

The successive polarographic determination of As(III) and As(V)

A method has been described for the successive polarographic determination of As(III) and As(V)in a sulphuric acid solution.A directly recorded polarogram shows a limiting current corresponding to the As(III) concentration, another polarogram, recorded with a second sample after reduction of As(V) to As(III) by hydrazine sulphate, gives a limiting current corresponding to the concentration As(II) + As(V).     

Fluorimetric trace determination of cerium(III) with sodium triphosphate

Sodium triphosphate acts as a specific reagent for enhancing the fluorescence intensity of cerium(III). The purpose of this study was to investigate the spectrofluorimetric determination of trace amounts of Ce(III) in sodium triphosphate solution. The excitation and emission wavelengths are 303.5 nm and 353 nm respectively. Optimum sodium triphosphate concentration is found to be 0.074 g l(-1) at room temperature. The fluorescence varies linearly with the concentration of cerium(III) in the range 0.001-45 mug ml(-1). The detection limit is 9.4 x 10(-4)mug ml(-1). The relative standard deviations for 30 mug ml(-1) and 0.05 mug ml(-1) Ce(III) in 0.074 g l(-1) sodium triphosphate solution are 1.1% and 0.72% respectively. Quenching effects of other lanthanides and some inorganic anions are described. This method is a direct and rapid analytical method for the determination of Ce(III) in rare earth mixtures and cerium concentrates.     

Spectrofluorometric determination of thallium(III) with pyrogallol red and 3,4,5,6-tetrachlorofluorescein

Summary A spectrofluorophotometric determination of thallium(III) is proposed. It is based on the enhancement of the fluorescence reaction of 3,4,5,6-tetrachlorofluorescein (TCF) with Pyrogallol Red (PR) by thallium(III) in the presence of Swanol (AM 301, lauryldimethyl aminoacetic acid betain) as an amphoteric surfactant. The method was found to be suitable for the determination of thallium(III) down to 4.0 g in 10.0 ml by measuring the difference in the relative fluorescence intensities of a TCF/PR/thallium(III) solution and a TCF/PR solution. The recovery test in artificial urine was satisfactory (96±2%).