Direct complexometric determination of aluminium in "alzinoy"

A simple and precise method for the complexometric determination of aluminium in "Alzinoy" (a binary alloy of aluminium and zinc) is described. After dissolution of the sample in hydrochloric acid, aluminium, zinc and any lead and iron are complexed with excess of EDTA. The excess of EDTA is titrated with lead solution, with Xylenol Orange as indicator. Ammonium fluoride is then added to decompose the Al-EDTA complex, and the EDTA liberated is titrated with lead solution. Four samples can be analysed in about 45 min.     

The determination of alumina in silicates (Rocks and Refractories)

New procedures have been developed for determining the alumina contents of silicate material (rocks and refractories). The material is first taken into solution by a peroxide sinter technique, followed by dissolving the sinter in warm water and the addition of sufficient hydrochloric acid to render the solution acid to litmus. A different technique is used for silicates containing less than 5% alumina. The majority of the silica is first removed by treating with hydrofluoric-sulphuric acids and the residue is fused with potassium bisulphate. Extractions with cupferron are next employed to remove iron, titanium, zirconium etc., and the aluminium is subsequently separated from other sample constituents by precipitating as its insoluble benzoate. After filtration the aluminium benzoate is dissolved in hydrochloric acid and the aluminium concentration determined volumetrically with ethylenediaminetetraacetic acid.     

Compleximetric titration of aluminum and zirconium in siliceous materials after alkali fusion of samples

Rapid methods for the determination of zirconium and aluminum in siliceous materials are described. Samples are decomposed by sodium carbonate—sodium borate fusion and dissolved in perchloric acid. The zirconium is titrated directly with standard EDTA solution at 90–95 ° C in 1 M perchloric acid solution with xylenol orange as the indicator. Aluminum is then complexed by boiling with an excess of EDTA and the free EDTA is back-titrated potentiometrically with standard zinc solution. Interference of titanium in the aluminum determination is prevented by lactic acid masking. The methods have been applied successfully to a wide variety of glass-ceramics, refractories and NBS minerals.     

EDTA滴定法连续测定铅精矿中铅和锌

建立了EDTA滴定法连续测定铅精矿中铅和锌的方法。试样用盐酸、硝酸、硫酸和氯酸钾分解。铅通过硫酸铅沉淀与其他干扰元素分离,沉淀溶解于乙酸-乙酸钠溶液中。在滤液中加入氨水、氟化钾使铁等干扰元素沉淀并与锌溶液分离。用二甲酚橙作指示剂,EDTA分别滴定溶液中的铅和锌。研究中测定了能力验证NILPT(2010)-0211铅精矿样品10-1和10-2中铅和锌,结果满意。     

The determination of zirconium in fluoride-containing solutions

In the recommended procedure the zirconium is first precipitated from solution as the insoluble barium fluozirconate. After separation, the precipitate is dissolved in a mixture of nitric and boric acids and the zirconium is then precipitated as its hydroxide. This precipitate is separated, dissolved in hydrochloric acid and this solution is evaporated to fumes of perchloric acid to remove completely fluoride ions. The zirconium content is then determined volumetrically by adding a slight excess of a standard solution of ethylenediaminetetra-acetic acid and back titrating with a standard iron solution at pH 2.3 using potassium benzohydroxamate as indicator and the photometric technique for end-point detection. This method is applicable to the determination of milligram amounts of zirconium in fluoride-containing nitric or hydrochloric acid solutions provided that the concentration of these acids is below 3N. It is also suitable for the determination of zirconium in the presence of any of the following elements - uranium, titanium, niobium, tantalum, molybdenum, tungsten, lead, iron, copper and tin.     

Separation gallium-fer en presence d'edta

Macro- or microquantities of gallium can be separated from iron by precipitating the latter with sodium hydroxide in the presence of EDTA. Nearly all the gallium remains in solution. After the separation of iron, gallium is extracted with tributylphosphate from 3 N hydrochloric acid medium, and then re-extracted into water. Gallium is finally determined by precipitation with cupferron and ignition to the oxide, or for trace amounts of gallium, by colorimetric determination with rhodamine B. The method was checked with radioactive gallium and iron.     

A rapid complexometric scheme for analysis of iron, aluminium, calcium and magnesium in slags

A simple and rapid complexometric method has been developed for the simultaneous determination of iron, aluminium, calcium and magnesium in a single solution in slags. Phosphorous and small amounts of chromium (1.5 mg) and vanadium (1 mg) do not interfere in the titration. Titanium and manganese are suitably masked with lactic acid and tetra sodium pyrophosphate, respectively. In a suitable aliquot, iron is titrated at pH 2 with EDTA, using sulphosalicylic acid as indicator. To this solution, excess disodium 1,2-cyclohexane diamine tetra acetic acid (DCTA) is added and aluminium is titrated by titrating the excess DCTA with standard copper sulphate solution at pH 3.5, using 1-(2-pyridylazo)-2-naphthol (PAN) as an indicator. A known excess of EDTA is added, the pH is raised to 10 and calcium and magnesium are jointly titrated by titrating the excess EDTA with copper sulphate solution, using PAN indicator. The Ca-EDTA complex is demasked with ammonium oxalate at pH 5 and the released EDTA equivalent to calcium is titrated with copper sulphate solution at pH 10 with PAN indicator. Results of analysis compare favourably with certified values and values obtained by standard methods for BCS and other slags. A set of five samples can be analysed for iron, aluminium, calcium and magnesium in four hours as compared to three days by the classical conventional method.     

Analytical aspects of some organic acids

Summary Back titrimetric procedures for the estimation of aluminium, zirconium, and thorium have been developed, which involved the adjustment of the concentration of the metallic salts, concentration of EDTA,ph, and temperature, addition of indicator solution (namely, 2-hydroxy3-naphthoic acid and back titration with standard 0.1 M ferric chloride solution. This method is based on the fact that the excess EDTA, which is added to the metal solutions may be back titrated with iron(III), which forms a highly coloured complex with the indicator, when present in slight excess. Quantities of aluminium, zirconium and thorium as small as 10.8, 4.6, 11.6 mg respectively, can be back titrated with in experimental error, when present in a volume of 100 ml.Part IV: See Z. analyt. Chem. 172, 356 (1960).     

Separation of large amounts of iron(III) from cobalt,nickel, and aliminum by combined ion exchange-solvent extraction

A method is described for the cation-exchange separation of large amounts of iron(III) from cobalt, nickel, and aluminium. On the strongly acidic Dowex 50-X8, iron(III) is not adsorbed from an 80% tetrahydrofuran-20% 3 M hydrochloric acid mixture, while cobalt, nickel, and aluminium are retained; a quantitative separation is thus possible. Cobalt and nickel or aluminium are then separated by elution with 90% tetrahydrofuran-10% 6 M hydrochloric acid. In these mixtures combined ion exchange-solvent extraction appears to occur; both ion exchange and liquid-liquid extraction are. effective simultaneously.     

Titrimetrische Bestimmung des Aluminiums in Silicatgesteinen mit potentiometrischer Indikation

Zusammenfassung Eine titrimetrische Aluminiumbestimmung in Silicatgesteinen mit potentiometrischer Indikation wird beschrieben. Ein Vergleich der Analysenergebnisse mit denen anderer Verfahren sowie die nach den Methoden der Fehlerrechnung erhaltenen Zahlenwerte beweisen die Brauchbarkeit des Verfahrens. Der Aufschluß des Probenmaterials erfolgt mit Flußsäure/Perchlorsäure. Die Störelemente Eisen, Titan und Zirkon werden mit Kupferron-Chloroformlösung aus stark salzsaurer Lösung extrahiert. Zum wäßrigen Extrakt wird 0,01 M ÄDTA-Lösung gegeben und der Überschuß mit 0,01 M Zinksulfatlösung potentiometrisch gegen Hexacyanoferrat(II)/(III) als Indicatorsystem zurücktitriert. Die Titration erfolgt automatisch. Das Verfahren benötigt keinen Farbindicator und ermöglicht daher auch die Aluminiumbestimmung in gefärbten Lösungen. Die Erfassung des Titrationsendpunktes ist objektiv.

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Titrimetric determination of aluminium in silicate rocks by potentiometric indication

A comparison of the analysis results with those of other methods and especially the numerical values according to the methods of the error calculation, prove the usefulness of the method described. The decomposition of the test material is carried out with hydrofluoric acid/perchloric acid. The interfering elements iron, titanium and zirconium are extracted from a strong hydrochloric acid solution by means of a cupferron-chloroform solution. 0.01 M EDTA solution is added to the aqueous extract, and its excess is back-titrated potentiometrically with 0.01 M zinc sulphate solution against hexacyanoferrate(II)/(III) solution as an indicating system. The titration takes place automatically. The method requires no colour indicator, thus allowing the determination of aluminium in coloured solutions, too. The registration of the end point of the titration gives a detached result.

     

Determination of zinc in blast furnace flue dusts

Two methods for the determination of zinc in blast-furnace flue dusts are described. One involves a solvent extraction step using methyl isobutyl ketone to separate the zinc from the bulk of the interfering elements, followed by a complexometric titration of the zinc with EDTA, using Eriochrome Black T as indicator. The other employs differential pulse polarography with a hydrochloric acid + pyridine supporting electrolyte. In this method, the interference of iron is prevented by reducing it with hydroxylamine hydrochloride; aluminium is complexed with potassium fluoride. Other elements, with the exception of cobalt, do not interfere. Excellent agreement between the two methods is obtained in the range 0.01–0.6% zinc.     

Selective masking and demasking for the stepwise complexometric determination of aluminium,lead and zinc from the same solution

Background  

A complexometric method based on selective masking and de-masking has been developed for the rapid determination of aluminium, lead and zinc from the same solution in glass and glass frit samples. The determination is carried out using potassium cyanide to mask zinc, and excess disodium salt of EDTA to mask lead and aluminium. The excess EDTA was titrated with standard Mn(II)SO₄ solution using Erichrome Black-T as the indicator. Subsequently selective de-masking agents – triethanolamine, 2,3-dimercaptopropanol and a formaldehyde/acetone mixture – were used to determine quantities of aluminium, lead and zinc in a stepwise and selective manner.     

The determination of metallic iron in the presence of fayalite

In a proposed new procedure the sample is treated with bromine, the excess of bromine removed, and the residue extracted with methanol. After filtration the filtrate is evaporated to remove methanol and the bromides are dissolved in hydrochloric acid for determination of metallic iron. The oxide residue from the filtration is fused in sodium peroxide and then dissolved in hydrochloric acid for the determination of iron present either as oxide or silicate. Iron in the hydrochloric acid solutions from the residue and filtrate is determined either by titration with standard potassium dichromate solution or by atomic-absorption spectrometry.     

Photometric determination of gallium with rhodamine b

Gallium is extractable as rhodamine B chlorogallate with benzene from 6M hydrochloric acid, and can be determined absorptiometrically or fluorimetrically in the extract. The interference of iron(III) is avoided by first separating gallium by extraction with isopropyl ether from hydrochloric acid solution containing titanous chloride. Traces of gallium can be determined in the presence of aluminium, indium, zinc, antimony, thallium, tungsten and other elements.     

Complexometric determination of aluminium, zirconium, and hafnium

Summary Methods for the complexometric titration of aluminium, zirconium and hafnium are described using pyrocatechol violet as indicator. The EDTA titration of zirconium and hafnium is performed in acid medium and that of aluminium in a solution buffered with acetate.

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Zusammenfassung Methoden zur komplexometrischen Titration von Aluminium, Zirkonium und Hafnium unter Verwendung von Brenzcatechinviolett als Indicator werden beschrieben. Die ÄDTA-Titration von Zirkonium und Hafnium erfolgt in relativ stark saurer Lösung, während die des Aluminiums in acetatgepufferter Lösung ausgeführt wird.

     

Indirect complexometric titration of sodium and potassium with EDTA

Summary Sodium is precipitated as sodium zinc uranyl acetate, filtered and dissolved in water, and zinc is titrated with EDTA using eriochrome black T as indicator. Potassium is precipitated as potassium sodium cobaltinitrite and dissolved in hot water containing little hydrochloric acid. The blue colored solution produced by cobalt in solution, with ammonium thiocyanate and acetone was titrated with EDTA until colorless. The results are good.The author is grateful to Prof. Philip W. West, Boyd Professor of Chemistry, Louisiana State University, for kindly providing the facilities to carry out the investigation.     

Flow-injection analysis of silicate rocks for total iron and aluminium

A flow-injection method is described for the spectrophotometric determination of total iron and aluminium in silicate rocks. Rock samples are opened up by fusion with a mixture of lithium carbonate and boric acid, the melt is taken up in 1M hydrochloric acid and the resulting solution is used for the determination of both iron and aluminium. The flow system for the determination of iron needs no particular reagents, involving simply measurement of the absorbance of the chloro-complex of iron(III) at 335 nm. The system for aluminium consists of the reduction of iron(III) to iron(II), colour development with Xylenol Orange (XO), destruction of XO-chelates other than that of aluminium by addition of EDTA and subsequent measurement of the absorbance of the aluminium-XO complex at 506 nm. The systems permit semi-automatic, rapid analysis of silicate rocks for iron and aluminium. Results obtained for standard rocks were in good agreement with the recommended values. The precision ranged from 0.1 to 0.9% for iron and from 0.3 to 0.7% for aluminium.     

Use of nitrosochromotropic acid as a metal indicator

Summary Nitrosochromotropic acid and copper give a purple coloured complex in the pH range 5.8–6.5, which is less stable than Cu(II)-EDTA complex. When milligramme quantities of copper solution containing few drops of nitrosochromotropic acid were titrated with EDTA the colour changes to light green or colourless. Copper can be titrated from 15–30° C, but at higher temperature low results are obtained due to dissociation of copper complex. Alkaline earths do not interfere in the titration of copper, but zinc, cadmium, nickel, cobalt, aluminium and iron(III) interfere. The interference of aluminium and iron(III) is masked by sodium fluoride. Microtitration can be carried out using nitrosochromotropic acid screened with xylene cyanol FF as metal indicator.     

The determination of beryllium in geological and industrial materials by atomic-absorption spectrometry after cation-exchange separation

A method is described for the determination of beryllium in geological and industrial samples. After dissolution of the sample in mineral acids, beryllium is separated from the matrix elements by chloroform extraction of its acetylacetonate from a solution of pH 7 containing ascorbic acid and EDTA. Beryllium is separated from the organic extract and from co-extracted aluminium by means of a column of the strongly acidic cation-exchanger Dowex 50; beryllium is adsorbed from a medium consisting of 60 % (v/v) tetrahydrofuran, 30 % (v/v) chloroform and 10 % (v/v) methanol containing hydrochloric acid, aluminium is removed with 0.4 M oxalic acid and after elution with 6 M hydrochloric acid, beryllium is determined by atomic-absorption spectrometry with a nitrous oxide-acetylene flame. The method was used to determine p.p.m. and sub-p.p.m. quantities of beryllium in geochemical reference materials, U₃O₃ and yellow cake samples, and manganese nodules.     

Rapid photometric determination of phosphorus in iron ores and related materials as phosphomolybdenum-blue

A rapid, simple and accurate method for determining phosphorus photometrically in iron ores and related materials, obviating the use of perchloric acid, is described. The sample is fused with sodium peroxide in a zirconium crucible and the melt dissolved in hydrochloric acid. The molybdenum-blue complex is developed by the addition of ammonium molybdate and hydrazine sulphate and the absorbance is measured at 725 nm. The range of the method is from 0.005 to 1.0% P. A batch of 6 samples can be analysed in about 2 hr.