In Process Citation

The sample (up to 5 mg) is destroyed by using a wet process in a glass flask of the Kjeldahl type. Aluminium cobalt, tin and iron are determined spectrophotometrically. The following reactions are used: complexation of aluminium by Alizarin Red S and calcium cobalt(II) by tiron tin(IV) by phenylfluorone, iron(III) by tiron.     

Reactions of palladium(II) and rhodium(III) with pyridylazo-2-naphthol and dithizone on PANV–KU-2 and PANV–AV-17 fibrous materials

Reactions of palladium(II) and rhodium(III) with dithizone (DT) on polyacrylonitrile fiber filled with an AV-17 anion exchanger (PANV–AV-17) and 1-(2-pyridylazo)-2-naphthol (PAN) immobilized on polyacrylonitrile fiber filled with a KU-2 cation exchanger (PANV–KU-2–PAN) are studied by diffuse reflection spectroscopy. Conditions of rhodium complexation on PANV–KU-2–PAN (ascorbic acid concentration, pH of solution in adsorption, and the duration of heating samples) and palladium complexation with DT after adsorption from a 0.1 M NaCl solution (pH 2) on PANV–AV-17 in the dynamic mode are found. The limits of detection for rhodium and palladium are 10 and 5 ng/mL, respectively. At 640 nm, the calibration graphs are linear in the ranges of palladium and rhodium concentrations 0.008–0.06 µg/mL and 0.02–0.2 µg/mL, respectively. The mutual influence of rhodium and palladium is studied. It is shown that the determination of palladium with DT on a PANV–AV-17 solid phase is not affected by the presence of a 5-fold amount of rhodium, and rhodium can be determined on PANV–KU-2–PAN at 590 nm in the presence of 2-fold amounts of palladium.     

Voltammetric determination of zirconium using azo compounds

The Optimum oconditions for zirconium complexation with azo compounds are found. The applicability of Eriochrome Red B, Calcon, and Calcion to the voltammetric determination of zirconium, total Zr(IV) and Hf(IV), and Zr(IV) in the presence of Zn(II), Cu(II), Cd(II), Ni(II), or Ti(IV) is demonstrated. The developed procedures are used to determine zirconium in a terbium alloy and in an alloy for airplane wheel drums.     

Sorption-spectrophotometric determination of zirconium and chromium(VI) from a single sample on a two-layer support using Arsenazo III and 1,5-diphenylcarbazide

The possibility of the sorption-spectrometric determination of zirconium(IV) and chromium(VI) from a single sample using a two-layer support made of polyacrylonitrile fiber filled with a PANF-KU-2 cation exchanger and PANF-AV-17 anion exchanger is studied. After sorption zirconium is determined with Arsenazo III on PANF-KU-2 and chromium is determined with 1,5-dipehnylcarbazide on PANF-AV-17. The sorption of zirconium and chromium is studied in the dynamic mode from solutions of HCl, HNO₃, and H₂SO₄ and the optimal conditions of the simultaneous sorption of zirconium on PANF-KU-2 and chromium on PANF-AV-17 from 0.25 M HCl is chosen. Diffuse reflection spectra of zirconium and chromium complexes have are on the solid phase and the conditions of zirconium determination are optimized. Calibration curves are linear in the range of zirconium and chromium concentration 0.005–0.025 μg/mL; the detection limits are 0.002 μg/mL. The selectivity of zirconium and chromium determination is tested in the presence of interfering ions. A procedure is developed for their determination from a single sample at zirconium to chromium ratios from 3: 1 to 1: 3.     

Application of the Combustion Method in a Closed Flask to the Lead Determination in Atmospheric Aerosols

Abstract

The destruction of the filter for metal determination in atmospheric aerosols is an important step in the analysis. Nowadays the decomposition of this kind of sample has not been completely solved, so it is interesting to study new methods for filter sample attack. In the present work the application of the combustion method in a closed flask for mixed cellulose esters filter decomposition for lead determination is proposed. For this purpose optimum operating conditions as stopper flask design, sample size, flask volume, shaking time and volume and concentration of absorbing solution are established, and accuracy and precision of the proposed method using AAS for the measurements is given. The results obtained by the closed flask combustion are compared with those found by wet attack with HNO₃. The method proposed is rapid, has low reagent contamination and no loss of lead by volatilization or by amalgamation occurs. This method shows an accuracy and a precision in good agreement with the standard method.     

Indicator Tubes and Indicator Powders for Determining Fluoride and Chloride Ions

Noncovalent immobilization of Arsenazo I, Alizarin Red, Xylenol Orange, and diphenylcarbazone by incorporation into silicic acid xerogels and modification of silica gels was studied, and procedures for determining fluoride and chloride ions by solid-phase spectrophotometry and test methods were developed. Reactions of immobilized reagents with aluminum(III), zirconium(IV), and mercury(II) were studied. The possibility of using immobilized reagent–metal ion–halide ion systems for the determination of halide ions was assessed. Indicator powders were proposed for determining 0.5–10 mg/L fluoride ions and 1–30 mg/L chloride ions, and indicator tubes were developed for determining 20–200 mg/L chloride ions. The determination of fluoride and chloride ions is based on exchange complexation reactions proceeding in the systems immobilized Xylenol Orange–zirconium(IV) and immobilized diphenylcarbazone–mercury(II), respectively. Performance characteristics of the developed procedures were estimated. The procedures were verified by determining halide ions in Narzan mineral water.     

Reaction of zirconium(IV) with 2,3,4-trihydroxiphenylazo-5′-sulfonaphthalene in the presence of diantipyrilmethane and its homologues

The effect of diantipyrilmethane and its homologues on the complexation of zirconium(IV) with 2,3,4-trihydroxiphenylazo-5′-sulfonaphthalene is studied, and conditions for the formation of mixed-ligand complexes are determined. Correlations between the acidity constants of diantipyrilmethane and its homologues and the stability constants and the specific conductivity of complexes, and degree of contrast, and the change in the Gibbs free energy are found for the complexation reaction. A method is developed for the selective photometric determination of zirconium in pyrite containing modified quartz diorite.     

Application of the isotope dilution technique for Zr determination in an irradiated cladding material by multiple collector-inductively coupled plasma mass spectrometry

The determination of ⁹³Zr concentration, a long-lived radionuclide present in spent nuclear fuel and in the structural components of nuclear reactors, is a major issue for nuclear waste disposal purpose and to validate neutronic calculation codes. To measure ⁹³Zr concentration in irradiated cladding material with a high precision, an analytical method based on the use of multiple collector-inductively coupled plasma mass spectrometer (MC-ICPMS) combined to isotope dilution technique was developed. First a radiochemical separation of zirconium from a zircaloy sample (a zirconium alloy used as a cladding material for nuclear fuel elements), has allowed to obtain a very pure zirconium fraction with no potential isobaric interferences for mass spectrometric measurements. Then as the determination of all zirconium isotope ratios in the sample is necessary for the isotope dilution method, a MC-ICPMS procedure was developed to perform these precise measurements. Finally, the determination of ⁹³Zr concentration in the same sample was performed, after preparation and calibration of a ⁹⁶Zr spike solution. The uncertainties obtained on isotope ratios of zirconium by MC-ICPMS were in the order of 0.1%. The final uncertainty obtained on the ⁹³Zr concentration in the nuclear material used and after chemical purification was lower than 0.6%.     

Simultaneous spectrophotometric determination of uranium and zirconium using cloud point extraction and multivariate methods

A cloud point extraction (CPE) process using the nonionic surfactant Triton X-114 to simultaneous extraction and spectrophotometric determination of uranium and zirconium from aqueous solution using partial least squares (PLS) regression is investigated. The method is based on the complexation reaction of these cations with Alizarin Red S (ARS) and subsequent micelle-mediated extraction of products. The chemical parameters affecting the separation phase and detection process were studied and optimized. Under the optimum experimental conditions (i.e. pH 5.2, Triton X-114?=?0.20%, equilibrium time 10?min and cloud point 45?°C), calibration graphs were linear in the range of 0.01?C3?mg?L^?1 with detection limits of 2.0 and 0.80???g L^?1 for U and Zr, respectively. The experimental calibration set was composed of 16 sample solutions using an orthogonal design for two component mixtures. The root mean square error of predictions (RMSEPs) for U and Zr were 0.0907 and 0.1117, respectively. The interference effect of some anions and cations was also tested. The method was applied to the simultaneous determination of U and Zr in water samples.     

Determination of selenium in drugs by oxygen flask combustion and ion chromatography

A method is described for the determination of trace selenium (impurities in medicinal organic compounds) by ion chromatography (IC) after oxygen flask combustion. All selenium compounds formed by oxygen flask combustion are converted to selenate ion by heating with nitric acid and potassium permanganate. The selenate ion is then determined by IC, using a simple recycle system to eliminate interfering ions. The detection limit of selenium is 0.4 nmol in 50 mg of sample. The recoveries of selenium added to seven drugs are ca. 95-103% with relative standard deviations of 1-6%.     

Early (Ti,Zr)-late (Rh,Ir) heteronuclear complexes with bridging sulphido ligands

We report in this account on the controlled synthesis of novel d⁰–d⁸ early-late heteropolynuclear diolefin and carbonyl clusters. The synthetic approach was based on additive–deprotonation reactions involving the titanium and zirconium bis-hydrosulphido complexes of formula [Cp₂Ti(SH)₂] and [Cp^tt₂Zr(SH)₂] and appropriate rhodium and iridium diolefin and carbonyl compounds. The significant differences between the resulting early-late complexes and their structures coming from the titanium or zirconium metalloligand precursors are highlighted. The catalytic activity of some representative titanium–rhodium and zirconium–rhodium compounds towards alkene hydroformylation was explored. Interestingly, the heterotetranuclear ‘CpTi(μ₃-S)₃Rh₃’ structure was maintained as such under mild conditions. To cite this article: L.A. Oro et al., C. R. Chimie 6 (2003) 000–000.     

Exthaktiv-Spekthophotometrische Bestimmung Von Rh(III) in Gegenwart Der Platinmetalle,Gold Und Silber Unter Anwendung Von 1-(2-Pyridylazo)-2-Naphthol

Abstract

A spectrophotometric method is described for the determination of 25–150μ;g of rhodium (III) using 1-(2-pyridylazo)-2-naphthol. One milligram of Ir(III) or Ir(IV), 200μ;g Ru(IV), 400μ;g Os(IV), 350μ;g Pt(IV), 5 mg Ag(I), and 100μ;g Au(III) do not interfere. Larger amounts of silver and gold are removed as AgCl and, after reduction with ascorbic acid, Au metal. A modification of the method permits the successive determination of 4–100μ;g of Hh(III) and 50–500μ;g of Pd(II) in a single sample.     

Solid phase extraction of zirconium as arsenazo(III) complex on agar and spectrophotometric determination

A new solid phase extraction method for the separation and determination of zirconium using agar as an adsorbent is described. The method is based on the adsorption of zirconium as arsenazo(III) complex on agar in a mini-column, elution with sulfuric acid-acetone mixture and determination by spectrophotometry. The effect of different parameters such as pH, concentration of the reagent, eluting reagent, and volume of the sample, amount of the adsorbent and interfering ions was investigated. The calibration graph was linear in the range of 5?C300 ng ml^?1 of zirconium under optimum conditions. The limit of detection based on 3S_b was 1.3 ng ml^?1 and the relative standard deviation (R.S.D) for ten replicate measurements of 15 and 200 ng ml^?1 of zirconium was 3.7 and 1.8%, respectively. The method was applied to the determination of zirconium in water and soil samples.     

Sorption-spectroscopy determination of zirconium on a PANV-KU-2 fibrous ion exchanger using Arsenazo III

The sorption and complexation of zirconium with Arsenazo III have been studied on a polyacry-lonitrile fibrous material filled with strongly acidic KU-2 cation exchanger in strongly acidic media. The optimal conditions have been chosen for the sorption-spectrophotometric and test determination of zirconium by diffuse reflection spectroscopy or visual testing. The limit of zirconium detection is 0.02 ??g/mL. The procedure was tested in the analysis of model solutions of ammonium molybdate and vanadate and copper chloride using the standard addition method.     

Determination of phenolic compounds using spectral and color transitions of rhodium nanoparticles

This work reports a new approach for the determination of phenolic compounds based on their interaction with citrate-capped rhodium nanoparticles. Phenolic compounds (i.e., catechins, gallates, cinnamates, and dihydroxybenzoic acids) were found to cause changes in the size and localized surface plasmon resonance of rhodium nanoparticles, and therefore, give rise to analyte-specific spectral and color transitions in the rhodium nanoparticle suspensions. Upon reaction with phenolic compounds (mainly dithydroxybenzoate derivatives, and trihydroxybenzoate derivatives), new absorbance peaks at 350 nm and 450 nm were observed. Upon reaction with trihydroxybenzoate derivatives, however, an additional absorbance peak at 580 nm was observed facilitating the speciation of phenolic compounds in the sample. Both absorbance peaks at 450 nm and 580 nm increased with increasing concentration of phenolic compounds over a linear range of 0–500 μM. Detection limits at the mid-micromolar levels were achieved, depending on the phenolic compound involved, and with satisfactory reproducibility (<7.3%). On the basis of these findings, two rhodium nanoparticles-based assays for the determination of the total phenolic content and total catechin content were developed and applied in tea samples. The obtained results correlated favorably with commonly used methods (i.e., Folin-Ciocalteu and aluminum complexation assay). Not the least, the finding that rhodium nanoparticles can react with analytes and exhibit unique localized surface plasmon resonance bands in the visible region, can open new opportunities for developing new optical and sensing analytical applications.     

Application of the combustion method in a closed flask to the lead determination in atmospheric aerosols

The destruction of the filter for metal determination in atmospheric aerosols is an important step in the analysis. Nowadays the decomposition of this kind of sample has not been completely solved, so it is interesting to study new methods for filter sample attack. In the present work the application of the combustion method in a closed flask for mixed cellulose esters filter decomposition for lead determination is proposed. For this purpose optimum operating conditions as stopper flask design, sample size, flask volume, shaking time and volume and concentration of absorbing solution are established, and accuracy and precision of the proposed method using AAS for the measurements is given. The results obtained by the closed flask combustion are compared with those found by wet attack with HNO3. The method proposed is rapid, has low reagent contamination and no loss of lead by volatilization or by amalgamation occurs. This method shows an accuracy and a precision in good agreement with the standard method.     

Spectrophotometric determination of total vicinal diketones with isoniazide and a zirconium salt

Summary A method has been worked out for the spectrophotometric determination of total vicinal diketones.It is based on the distillation of diacetyl and/or 2,3-pentanedione, the subsequent condensation with isoniazide (yielding the corresponding hydrazones), the complexation with zirconium(IV) and the photometric measurement of the resulting yellow complexes at 410 nm. The two reactions were studied separately. Variables such as pH, heating time, and excess reactives are discussed. The method may be used for the determination of these compounds in foods.     

Infrared macro and semimicro determination of nitrogen in raw nitrocellulose and nitrocellulose contained in propellants

The infrared procedure for the determination of nitrogen in raw nitrocellulose has been improved. In the original method 0.31-0.32 g of sample was dissolved in 45 ml of tetrahydrofuran, the solution was weighed, and the infrared peak at 6.0 microm was measured. The calibration curve was prepared by plotting absorbance against mg of nitrogen per g of solution. The method has the disadvantage that the height of the peak is affected by the sample weight. In the improved method the error due to the sample weight is eliminated by using 0.3000 g of sample and diluting to 50 ml in a volumetric flask. The calibration curve is prepared by plotting absorbance against % nitrogen. The method was extended to the semimicro scale by using a 30.0-mg sample and diluting to 5 ml in a volumetric flask. The method has been applied on the macro and semimicro scales to the direct determination of nitrogen in nitrocellulose after a methylene chloride extraction. The amounts of graphite and inorganic salts found in nitrocellulose-base propellants do not interfere, but a correction must be made to refer the results to 0.3000 g of nitrocellulose for the macro method or 30.0 mg of nitrocellulose for the semimicro method. The same calibration curve is used for all procedures.     

The determination of zirconium in its binary alloys with niobium and tantalum

A procedure is presented for the determination of zirconium in the presence of niobium or tantalum. The bulk of the niobium or tantalum is first removed by extracting with hexone from a 10M hyclrofluoric acid, 6M sulphuric acid solution of the sample. The zirconium is then. separated from any unextractcd earth, acid element by precipitation with ammonium hydroxide followed by the addition of hydrogen peroxide. Under these conditions, both the niobium and tantalum form soluble peroxy complexes whereas the zirconium is completely precipitated from solution. After the separation of the precipitate by filtration, it is re-dissolved in hydrochloric acid and the zirconium concentration is finally determined by titration with ethylenediaminetetraacetic acid.     

The role of complexing ligands in the formation of non-aggregated nanoparticles of zirconia

The hydrolysis and condensation of zirconium n-propoxide in n-propanol have been chemically controlled via the complexation of the zirconium precursor with acetylacetone. The size of the zirconium oxide-based particles is mainly controlled by the complexation ratio x=[acac]/[Zr]. the mean size increases from nanometric to submicronic range when x decreases from 1 to 0.1. Amorphous colloidal particles are obtained at room temperature. They result from a competitive growth/termination mechanism of zirconium-oxo species in the presence of acac surface capping agents. However non-aggregated nanocrystalline particles of tetragonal zirconia, about 2 nm in diameter are formed upon aging at 60°C when hydrolysis is performed in the presence of paratoluene sulfonic acid (PTSA).