Determination of niobium and tantalum in binary alloys and zirconium alloys

Recent developments in the metallurgy of niobium, tantalum and zirconium have necessitated provision of analytical procedures for determining niobium and tantalum in the presence of each other and in the presence of zirconium. For this purpose, absorptioinetric procedures based on the formation of yellow coloured complexes, between pyrogallol and niobium or tantalum, have been critically examined. Direct absorptiometric procedures are described, which are suitable for determining niobium or tantalum in the range 2 to 7%; when either of these metals exceeds 7%, differential absorptiometric procedures are recommended. Corrections must lie made for absorption due to the presence of other metals which form complexes with pyrogallol. In tlie determination of niobium or tantalum up to 5%, the precision of the method is about ±0.05%. About 12 determinations can be made in a day, by one analyst.     

Separation and gravimetric determination of niobium,tantalum and titanium by precipitation with n-benzoyl-n-phenylhydroxylamine

A method is described for the separation and gravimetric determination of niobium, tantalum and titanium by precipitation with N-benzoyl-N-phenylhydroxylamine. Titanium is kept in solution with EDTA and hydrogen peroxide, and the earth acids are precipitated in 1N sulphuric acid Niobium and tantalum are separated and determined by a modification of the method of MAJUMDAR AND MUKHERJEE. All three metals are finally precipitated with N-benzoyl-N-phenyl-hydroxylamine. In the analysis of complex materials niobium, tantalum and titanium are separated from other constituents by a double precipitation with N-benzoyl-N-phenylhydroxylamine in the presence of EDTA and tartaric acid     

The separation and determination of niobium and tantalum by partition chromatography

A procedure is outlined for the separation and determination of niobium and tantalum by paper chromatography. A mixture of methyl isobutyl ketone and hydrofluoric acid was used as solvent and the metals were detected by means of 8-hydroxyquinoline. The minimum amount of each element detectable is 20 μg.

The procedure was applied successfully to the quantitative determination of small amounts of niobium and tantalum in a steel.     

Fast simultaneous determination of niobium and tantalum by Kalman Filter analysis with flow injection chemiluminescence method.

A fast and highly efficient Kalman Filter analysis-flow injection chemiluminescence (FI-CL) method was developed to simultaneously determine trace amounts of niobium and tantalum in geological samples. The method, without the boring process of separation and dear instruments, is suitable for field scene analysis. The mixed chemiluminescence kinetic curve was analyzed by a Kalman Filter (KF) in this method to realize the simultaneous determination of niobium and tantalum. Possible interference elements in the determination were investigated. Under the selected conditions, the detection limits (3sigma, n = 11) of niobium(V) and tantalum(V) were 2.1 x 10(-3) microg g(-1) and 4.0 x 10(-3) microg g(-1), respectively, and the relative standard deviations were 4.9% and 3.3% (n = 9). The method was applied to the determination of niobium and tantalum in geological samples with satisfactory results.     

Spectrophotometric determination of niobium in tantalum metal

A new method for the determination of traces of niobium in tantalum metal has been developed. The niobium is separated from tantalum by solvent extraction with hexone from hydrofluoric acid-hydrochloric acid solution, and from molybdenum and tungsten by solvent extraction with oxine-chloroform solution from ammoniacal citrate solution. The niobium is then determined by the spectrophotometric thiocyanate method.     

Colorimetric determination of niobium in titanium alloys

There is need for a method for the determination of niobium in titanium alloys, since niobium-titanium alloys are becoming increasingly important. The determination of niobium in this type of alloy is an extremely difficult matter. Many approaches were tried before the problem was solved. In the method proposed in this paper the sample is dissolved in a mixture of hydrofluoric and nitric acids, the solution evaporated to a small volume, and boric acid added. Two tannic acid separations are then made to separate the niobium from the bulk of the titanium. The niobium, is determined colorimetrically by the thiocyanate method using a water-acetone medium. A study was made of the possible interference of elements that might be present in titanium alloys. It was found that the presence of tantalum causes two opposing tendencies. Tantalum can cause high results for niobium because it forms a complex with thiocyanate which is visually colorless but shows some absorption. Tantalum can cause low results for niobium by hindering the development of the niobium color. The resultant effect of the tantalum depends upon the amount of tantalum present, the amount of niobium present and the ratio of tantalum to niobium. The presence of more than one per cent. tungsten can lead to high results for niobium. Other elements that might be present in titanium alloys do not interfere with the method. The procedure is designed for titanium alloys containing 0.05 to 10 per cent. niobium. The method is reasonably rapid. Six determinations can be finished in two days. The method should be applicable to many other materials besides titanium alloys.     

Determination of niobium and tantalum in some ores and special alloys by inductively coupled plasma atomic emission spectrometry

A fast analytical method for the determination of niobium and tantalum in ores and special alloys by inductively coupled plasma atomic emission spectrometry has been developed. Optimum conditions for the determination of both metals in the plasma were worked out and possible interferences were studied before attempting the determination in the real samples. Ores are dissolved in a mixture of HCl, HF and H₃PO₄ acids while for the special alloy a HCl+H₂O₂ mixture is used. The resulting solutions are diluted to the mark with tartaric acid before their final direct nebulization into the plasma. Other elements present did not interfere in the determination of Nb or Ta at concentration levels similar to those found in the analyzed samples. The results obtained determining niobium and tantalum in pyrochlore and special alloys by the proposed procedure are in good agreement with the certified values.     

N-acetylsalicyloyl-N-phenylhydroxylamine as an analytical reagent Determination of niobium and tantalum in the presence of each other

N-Acetylsalicyloyl-N-phenylhydroxylamme is proposed for the separation of niobium(V) and tantalum(V) and their gravimetric determination. Niobium is precipitated at pH 5.5-6.5 by the reagent and the complex is weighed directly. Tantalum is precipitated from 1-2M hydrochloric acid solutions and the complex is ignited to tantalum pentoxide. The method is fairly selective. In the presence of thiocyanate the reagent forms an extractable complex with niobium. The reaction forms the basis of a selective and sensitive spectrophotometric determination of niobium.     

Determination of manganese in high-purity niobium, tantalum, molybdenum and tungsten metals with pan

A spectrophotometric method for the determination of 0.0005-0.10% of manganese in high-purity niobium, tantalum, molybdenum and tungsten metals is described. The matrix materials are separated from the manganese by extraction as cupferrates, after sample dissolution, then the red complex formed between manganese(II) and 1-(2-pyridylazo)-2-naphthol, PAN, is extracted into chloroform from an ammoniacal tartrate-cyanide medium. The absorbance of the extract is determined at 562 mmicro. With the exception of zinc and lead, other impurities present in the four high-purity metals described do not interfere with the proposed method.     

Determination of niobium in zirconium-niobium alloys

A rapid control determination of niobium in 50% zirconium/50% niobium master-alloy is described; it is a direct spectrophotometric procedure, based on the reaction of niobium ions with hydrogen peroxide in concentrated sulphuric acid. The procedure is suitable for the examination of zirconium alloys containing niobium in the range 0.1 to about 60%. At least 1% of chromium, cobalt, copper, manganese, nickel or tantalum, does not interfere. Interference due to optical absorption by the peroxy-complexes of titanium, tungsten, molybdenum and vanadium is not significant in the determination of niobium above about 1%, provided that these metals are not in excess of about 0.5%, 0.25%, 0.1% and 0.02%, respectively. To compensate for optical absorption due to iron(III), a solution of the sample, not treated with peroxide, is used.     

Substoichiometric extraction of tantalum with diantipyrylmethane

Diantipyrylmethane is used for substoichiometric extraction of tantalum from 1—4M hydrofluoric acid into 1,2-dichlorethane. The selectivity of the method is good, niobium and antimony(V) being the main inteferences. The stoichiometric composition of the tantalum/diantipyrylmethane complex is 1:1. The method was usef for the determination of trace amounts of tantalum (0.52 ± 0.05 μ g^?1) in a lake sediment (Bodensee/Lake Constance) by neutron activation/μ-spectrometry. Tantalum was determined in niobium samples by an isotope dilution procedure after separation of the matrix on a polyurethane foam column loaded with diantipyrylmethane.     

Spectrophotometric Determination of Simultaneously Present Niobium and Tantalum

The formation of niobium(V) and tantalum(V) complexes of 2,3,4-trioxyphenylazo-5-sulfonaphthalene in the presence of cetyltrimethylammonium bromide was studied by spectrophotometry. The effect of surfactants on the chemical and analytical properties of niobium(V) and tantalum(V) complexes of this reagent was studied. Procedures were developed for the spectrophotometric determination of niobium and tantalum present simultaneously as mixed-ligand complexes. The procedures were tested on model solutions.     

Criteria for selecting analytical wavelengths for multicomponent mixtures by the CPA matrix method and simultaneous spectrophotometric determination of niobium and tantalum

The reversed matrix representation of the Lambert-Beer law (CPA matrix method) is applied in simultaneous spectrophotometric determinations. Restrictions on the selection of analytical wavelengths in applying the CPA matrix method are investigated experimentally and theoretically. Four criteria for selecting suitable wavelengths are described. A spectrophotometric procedure for niobium and tantalum with salicylfluorone and cetyltrimethylammonium bromide in the presence of tartaric acid was developed and used for the simultaneous determination of niobium and tantalum by the CPA matrix method. The absorption maxima were at 520 and 513 nm, respectively. Measurements at six wavelengths in the range 500–530 nm provided data from which niobium (0.04–0.4 μm ml^?1) and tantalum (0.08–0.8 μg ml^?1) were evaluated, with relative standard deviations of <2.     

Analytische Bestimmung von Niob,Tantal, Phosphor,Chlorid und 2,2-Dipyridyl in einigen Komplexverbindungen

Zusammenfassung Die analytische Bestimmung der Metalle, des Dipyridyls und der Chloride in Oxo-chloro-alkoxo-dipyridyl-Komplexverbindungen des Niobs und Tantals wurde beschrieben. Eine modifizierte Methode der Dipyridylanalyse, wie auch der Chloridbestimmung in Gegenwart von Dipyridyl wurde angegeben. Die radiometrische Metallbestimmung in Extraktionsverbindungen von Niob und Tantal mit Di-oktyl-methylenbis-phosphonsäure wurde dargelegt.

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Summary The analytical determination of metals, dipyridyl and chlorides in oxochloro-alkoxo-dipyridyl complex compounds of niobium and tantalum is described. A modified procedure of the dipyridyl analysis and also of the determination of chloride in the presence of dipyridyl is given. The radiometric determination of the metals in extraction compounds of niobium and tantalum with di-octyl-methylene-bis-phosphonic acid is discussed.

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Résumé On décrit le dosage des métaux, du dipyridyle et des chlorures dans les composés complexes oxo, chloro, alcoxo, dipyridyle, du niobium et du tantale. On indique une méthode modifiée pour le dosage de dipyridyle ainsi que pour la détermination des chlorures, en présence de dipyridyle. On décrit le dosage radiométrique des métaux dans les produits d'extraction du niobium et du tantale par l'acide di-octyl-méthylène-bis-phosphonique.

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Vorgetragen beim Symposium für analytische Chemie in Graz, 29. September bis 1. Oktober 1965.     

Precipitation and determination of tantalum and niobium from homogeneous solution with 3:3' :4' :5:7-pentahydroxyflavanone

3:3,:5:7-Pentahydroxyflavanone in fairly concentrated acidic solution (6-9N) does not precipitate tantalum and niobium ; however, on heating or boiling, in the presence of air, this flavanone is transformed into 3:3':4':5:7-pentahydroxyflavone, which precipitates any tantalum and niobium present in the solution. Under the precipitation conditions, racemisation of the flavanone also takes place. The racemised flavanone which is less soluble than the original d-form may accompany the tantalum and niobium precipitates without affecting the quantitative determination of these elements.

The precipitation of the tantalum and niobium complexes can be controlled by regulating the acidity and the duration of boiling, as well as the concentration of the flavanone. Experimental data and procedures are given for the precipitation and determination from homogeneous solution of tantalum and niobium complexes. Zirconium and molybdenum do not interfere with the determination. Titanium must be absent or present only in minute quantity.

Since the generation of the precipitating reagent, flavone, from the flavanone is comparatively slow, the precipitation of tantalum and niobium is uniform throughout the solution. By this technique, adsorption and co-precipitation of potassium and sulphate ions in the solution are shown to be negligible. This is in contrast to the less effective dropwise addition of the flavone reported by earlier investigators, in which adsorption and co-precipitation were pronounced.

In the present study, tantalum and niobium oxides were fused with potassium bisulphate. There is no necessity using hydrofluoric acid to dissolve these oxides and therefore no polyethylene apparatus is required.     

Spektrophotometrische Bestimmung von Tantalspuren in Niob mit Malachitgrün

Traces of tantalum are separated from niobium by extraction from hydrofluoric acid solution with methylisobutyl ketone. The determination of the separated trace amounts of tantalum is based upon their conversion to a complex with malachite green, the absorbance of which is measured at 635 nm. 0.2 μg of tantalum can be determined in 0.5 g of niobium metal.     

双波长分光光度法同时测定铌和钽

双波长分光光度法测定混合组分已被广泛应用,目前提出的有等吸收或K-系数双波长法、双显色双波长法及双峰双波长法等。由于铌钽性质相似,不易完全分离,已有人提出同时分析的方法。最近,文献报道了以5-Br-PADAP为显色剂用等吸收     

Analysis of alloys of titanium,niobium and tantalum by ion exchange

A procedure for the analysis of alloys of titanium, niobium and tantalum is described. After dissolution the metals are separated by ion exchange in hydrochloric-hydrofluoric acid media. Finally the metals are determined spectrophotometrically,     

Spectrophotometric determination of tantalum as reduced 12-molybdotantalic acid

A simple sensitive spectrophotometric method for the determination of tantalum is described. The method is based on the reaction of sodium molybdate with tantalum at pH 1.5–2.0. The resulting 12-molybdotantalic acid is reduced and the absorbance measured at 820 mμ. The method is subject to a number of interferences but is applicable in the presence of several-fold excesses of niobium and titanium.     

The polarography of molybdenum,titanium and niobium in solutions of organic acids

Further work on the polarographic reduction of molybdenum(VI), niobium(V) and titanium(IV) in base electrolytes containing organic acids is reported. A base electrolyte of 0.5 M citric acid-0.025 M sulphuric acid-0.05 M thorium nitrate proved suitable for the determination of molybdenum and titanium in the presence of niobium, tantalum, tungsten and zirconium. A direct polarographic method using this base electrolyte is described for the determination of molybdenum in a niobium base alloy.