Determination of tellurium in copper, lead and selenium by atomic-absorption spectrometry after extraction of the trioctylmethylammonium-tellurium bromide complex

A simple, rapid and sensitive combined solvent extraction and atomic-absorption spectrometric method has been developed for the determination of tellurium in copper, lead, selenium and blister copper. Tellurium is extracted as the trioctylmethylammonium-tellurium(IV) bromide complex into butyl acetate and determined by flame atomic-absorption spectrometry of the extract. As little as 1 mug of tellurium in a sample can be determined. The extraction of tellurium from hydrobromic acid solution with trioctylamine has also been investigated.     

Solvent extraction and separation of gallium, indium and thallium with N-benzylaniline

A simple and rapid method is proposed for the separation of tervalent gallium, indium and thallium by solvent extraction with N-benzylaniline in chloroform from different concentrations of hydrochloric acid. Thallium and gallium are extracted from 1M and 7.0-7.5M hydrochloric acid respectively. Indium is finally extracted from hydriodic acid. These metals in the final extracts are determined complexometrically. Interference from some cations can easily be eliminated by reduction with sulphite, followed by selective oxidation of thallium(I) to thallium(III) with saturated bromine water, and from others by the use of thioglycollic acid as a masking agent in the extraction of gallium and indium. Most common anions cause no interference. Log-log plots of distribution coefficients vs. concentration of amine for gallium, indium and thallium indicate a 2:1 limiting mole ratio of amine to these metals.     

Determination of gold in silver, copper, lead, selenium and anode slime by atomic-absorption spectrometry

A simple and sensitive combined solvent-extraction and atomic-absorption spectrometric method has been developed for the determination of gold in silver, copper, lead, selenium and anode slime. Samples are decomposed with hydrochloric and nitric acids, and gold is extracted as the trioctylmethylammonium-gold bromide complex and determined by atomic-absorption spectrometry by direct spraying of the extract into the flame. Optimal conditions for the extraction and determination of gold have been established. As little as 0.5 mug of gold in a sample can be determined. The extraction of gold from hydrochloric or hydrobromic acid solution with trioctylamine or trioctylmethylammonium chloride (or bromide) has also been investigated.     

Flame and flameless atomic-absorption determination of tellurium in geological materials

The sample is digested with a solution of hydrobromic acid and bromine and the excess of bromine is expelled. After dilution of the solution to approximately 3 M in hydrobromic acid, ascorbic acid is added to reduce iron(III) before extraction of tellurium into methyl isobutyl ketone (MIBK). An oxidizing air-acetylene flame is used to determine tellurium in the 0.1–20 ppm range. For samples containing 4–200 ppb of tellurium, a carbon-rod atomizer is used after the MIBK extract has been washed with 0.5 M hydrobromic acid to remove the residual iron. The flame procedure is useful for rapid preliminary monitoring, and the flameless procedure can determine tellurium at very low concentrations.     

Separation of bismuth from gram amounts of thallium and silver by cation-exchange chromatography in nitric acid

Traces and small amounts of bismuth can be separated from gram amounts of thallium and silver by successively eluting these elements with 0.3M and 0.6M nitric acid from a column containing 13 ml (3 g) of AG50W-X4, a cation-exchanger (100-200 mesh particle size) with low cross-linking. Bismuth is retained and can be eluted with 0.2M hydrobromic acid containing 20% v/v acetone, leaving many other trace elements absorbed. Elution of thallium is quite sharp, but silver shows a small amount of tailing (less than 1 gmg/ml silver in the eluate) when gram amounts are present, between 20 and 80 mug of silver appearing in the bismuth fraction. Relevant elution curves and results for the analysis of synthetic mixtures containing between 50 mug and 10 mg of bismuth and up to more than 1 g of thallium and silver are presented, as well as results for bismuth in a sample of thallium metal and in Merck thallium(I) carbonate. As little as 0.01 ppm of bismuth can be determined when the separation is combined with electrothermal atomic-absorption spectrometry.     

Atomabsorptionsspektrometrische Bestimmung von Indium in Schwefelkiesen, Abbr?nden und Zwischenprodukten der chlorierenden R?stung

Zusammenfassung Es wird über ein Verfahren zur Bestimmung von Indium in Schwefelkiesen, Abbränden und Produkten der chlorierenden Röstung mit Hilfe der atomaren Absorption berichtet. Indium wird durch Extraktion mit Diisopropyläther aus 6 N bromwasserstoffsaurer Probelösung abgetrennt. Nach Reextraktion mit 0,5 N Salzsäure wird der Indiumgehalt durch Extraktion aus 3 N bromwasserstoffsaurer Lösung in Methylisobutylketon überführt. Der Ketonextrakt wird direkt am Atomabsorptionsspektrometer gemessen. Der Variationskoeffizient betrug 32% bei 2 g/t bzw. 15% bei 10 g/t.

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Determination of indium in pyrites, pyrite cinders, and intermediate products of chlorinating roasting by atomic-absorption spectrometry

Indium is separated from the 6 N hydrobromic acid sample solution by extraction with diisopropyl ether. After re-extraction with 0.5 N hydrochloric acid the indium content is transferred into methyl isobutyl ketone by extraction from 3 N hydrobromic acid solution. The ketone extract is directly measured in the atomic-absorption spectrometer. The standard deviation is 32% for 2 g/t and 15% for 10 g/t.

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Herrn Prof. Dr. E. Asmus zum 60. Geburtstag gewidmet.     

The separation of tellurium and selenium by polyurethane foam sorbents

Tellurium and selenium can be sorbed from hydrochloric acid and hydrobromic acid solution by both polyether and polyester-based polyurethane foam. Although some acid is needed, the substitution of sodium chloride or sodium bromide increases the extraction significantly. Tellurium is extracted rapidly with > 99% sorbed in 2 min from 1.0/5.0M and 2.0/4.0M hydrochloric acid/sodium bromide. Selenium can also be sorbed quantitatively but much more slowly so that a separation is possible based on the relative rates of extraction. The capacity of polyether foam is 3% by weight of tellurium.     

Determination of silver, antimony, bismuth, copper, cadmium and indium in ores, concentrates and related materials by atomic-absorption spectrophotometry after methyl isobutyl ketone extraction as iodides

Methods for determining ~ 0.2 mug g or more of silver and cadmium, ~ 0.5 mug g or more of copper and ~ 5 mug g or more of antimony, bismuth and indium in ores, concentrates and related materials are described. After sample decomposition and recovery of antimony and bismuth retained by lead and calcium sulphates, by co-precipitation with hydrous ferric oxide at pH 6.20 +/- 0.05, iron(III) is reduced to iron(II) with ascorbic acid, and antimony, bismuth, copper, cadmium and indium are separated from the remaining matrix elements by a single methyl isobutyl ketone extraction of their iodides from ~2M sulphuric acid-0.1M potassium iodide. The extract is washed with a sulphuric acid-potassium iodide solution of the same composition to remove residual iron and co-extracted zinc, and the extracted elements are stripped from the extract with 20% v v nitric acid-20% v v hydrogen peroxide. Alternatively, after the removal of lead sulphate by filtration, silver, copper, cadmium and indium can be extracted under the same conditions and stripped with 40% v v nitric acid-25% v v hydrochloric acid. The strip solutions are treated with sulphuric and perchloric acids and ultimately evaporated to dry ness. The individual elements are determined in a 24% v v hydrochloric acid medium containing 1000 mug of potassium per ml by atomic-absorption spectrophotometry with an air-acetylene flame. Tin, arsenic and molybdenum are not co-extracted under the conditions above. Results obtained for silver, antimony, bismuth and indium in some Canadian certified reference materials by these methods are compared with those obtained earlier by previously published methods.     

Column chromatographic separation of gallium, indium and thallium

Distribution ratios are given for the extraction of gallium-(III), indium(III) and thallium(III) from aqueous solutions of hydrobromic acid into di-isopropy ether and isobutyl methyl ketone. Based on the results obtained, a scheme is presented for the quantitative separation of these elements from each other by liquid-liquid partition chromatography. The effect of a number of other metal ions upon the separation is also studied. The separation method has been applied to the analysis of a series of lead-indium alloys.     

Atomic-absorption spectrophotometric determination of antimony, arsenic, bismuth, tellurium, thallium and vanadium in sewage sludge

Electrothermal atomic-absorption spectrophotometry (AAS), by use of a graphite furnace, in conjunction with sample pretreatment by homogenization, was evaluated as a rapid method for the determination of bismuth, thallium and vanadium in sewage sludge. This method was compared with use of flame, electrothermal and hydride-generation (for bismuth) AAS in conjunction with conventional acid digestion and dry-ashing pretreatments and was found to be applicable to this type of sample. Comparisons were also made between flame and hydride-generation AAS in conjunction with an acid digestion pretreatment for the determination of antimony, arsenic and tellurium in sewage sludge. The hydride-generation technique was considered the better for waste-water samples because of its greater sensitivity.     

Determination of indium and thallium by hydride generation and atomic-absorption spectrometry

Hydride generation coupled with atomic-absorption spectrometry was applied to the determination of indium and thallium. The hydrides were generated in 1M HCl (In) and 1-1.5M HCl or HNO(3) (Tl) with 1% NaBH(4) solution, and were flushed with argon into an electrically heated silica tube. The characteristic mass for indium and thallium were 0.13 and 0.12 mug, respectively.     

Determination of tellurium in ores, concentrates and related materials by graphite-furnace atomic-absorption spectrometry after separations by iron collection and xanthate extraction

A method for determining approximately 0.01 mug/g or more of tellurium in ores, concentrates, rocks, soils and sediments is described. After sample decomposition and evaporation of the solution to incipient dryness, tellurium is separated from > 300 mug of copper by co-precipitation with hydrous ferric oxide from an ammoniacal medium and the precipitate is dissolved in 10M hydrochloric acid. Alternatively, for samples containing 300 mug of copper, the salts are dissolved in 10M hydrochloric acid. Tellurium in the resultant solutions is reduced to the quadrivalent state by heating and separated from iron, lead and various other elements by a single cyclohexane extraction of its xanthate complex from approximately 9.5M hydrochloric acid in the presence of thiosemicarbazide as a complexing agent for copper. After washing with 10M hydrochloric acid followed by water to remove residual iron, chloride and soluble salts, tellurium is stripped from the extract with 16M nitric acid and finally determined, in a 2% v/v nitric acid medium, by graphite-furnace atomic-absorption spectrometry at 214.3 nm in the presence of nickel as matrix modifier. Small amounts of gold and palladium, which are partly co-extracted as xanthates if the iron-collection step is omitted, do not interfere. Co-extraction of arsenic is avoided by volatilizing it as the bromide during the decomposition step. The method is directly applicable, without the co-precipitation step, to most rocks, soils and sediments.     

Determination of tellurium in geochemical materials by flameless atomic-absorption spectroscopy

A method is described for the determination of tellurium at nanogram levels in rocks and in other complex materials by the use of flameless atomic-absorption spectroscopy. A very selective organic extraction procedure is applied to avoid matrix interference effects during extraction of Te and the atomization stage in the graphite furnace. Prior separation of iron and other interfering elements is achieved by a combined cupferron-ethyl acetate extraction. Tellerium is extracted from 6M hydrochloric acid with MIBK and stripped into aqueous medium. Pipetting of the aqueous extract into the graphite furnace gives fairly good instrumental reproducibility (2-3% error). Detection limits of about 10 ppM Te for a 0.5-g sample have been achieved with the medium-performance apparatus used. Results for Te in some geochemical reference materials are reported. Indications are given for the determination of Sb and Mo in the same solutions.     

Determination of silver, bismuth, cadmium, copper, iron, nickel and zinc in lead- and tin-base solders and white-metal bearing alloys by atomic-absorption spectrophotometry

A simple atomic-absorption spectrophotometry method is described for the determination of silver, bismuth, cadmium, copper, iron, nickel and zinc in lead- and tin-base solders and white-metal bearing alloys, with use of a single sample solution. The sample is dissolved in a mixture of hydrobromic acid and bromine, then fumed with sulphuric acid. The lead sulphate is dissolved in concentrated hydrochloric acid. The method is particularly suitable for the determination of silver and bismuth, which are co-precipitated with lead sulphate. The other elements can also be determined after removal of the lead sulphate by filtration.     

Extraction-spectrophotometric determination of thallium in high-purity indium

Trace amounts of thallium in high-purity indium are separated from the matrix by extraction from 6M hydrochloric acid by di-isopropyl ether. On shaking the extract with Brilliant Green in 0.15M hydrochloric acid, an ion-association complex is formed in the organic phase. Interference of other elements is removed by their reduction with metallic copper and scrubbing. The proposed method permits determination of 10(-5)-10(-6)% thallium in high-purity indium with good precision and accuracy.     

An evaluation of four titrimetric methods for the determination of lead in ores

Four titrimetric methods for the determination of lead in ores were evaluated. In the absence of bismuth and indium, a method based on EDTA titration of lead, after chloroform extraction of lead diethyldithiocarbamate, yields accurate and more precise results than the other methods evaluated. Interference from indium can be avoided by di-isopropyl ether extraction of its bromide from 6M hydrobromic acid. Interference from bismuth can be eliminated by separating it from lead by chloroform extraction of its xanthate from 2M hydrochloric acid-tartaric acid media.     

Extraction—spectrophotometric determination of traces of thallium in lead,cadmium, indium and zinc metals with tri-n-octylamine

A sensitive spectrophotometric method is described for the determination of thallium in lead, cadmium, indium and zinc metals. Optimal conditions have been established for the extraction and determination of thallium. Thallium is extracted as its bromo complex with tri-n-octylamine and then converted to an iodo complex, the absorbance of which is measured at 400 nm. As little as 1 p.p.m. of thallium in lead, cadmium and zinc metals, and 2 p.p.m. of thallium in indium metal can be determined.     

An extraction study of gallium, indium and thallium using TPASO as an extractant

A method is proposed for the extraction and individual separation of trivalent gallium, indium and thallium from salicylate media using triphenylarsine oxide dissolved in toluene as an extractant. The optimum extraction conditions are evaluated and described. The extracted metal ions are stripped and estimated spectrophotometrically following complexation with 4-(2-pyridylazo) resorcinol. A possible mechanism of the extraction is discussed. The method permits rapid and precise individual separation of gallium (III), indium (III) and thallium (III) and is applicable to the analysis of alloy samples.     

Interference caused by indium in the atomization of Ag, Bi, Cd, Sn, and Tl in ETA-AAS

The depression of the signals for Ag, Bi, Cd, Sn, and Tl trace determination by ETA-AAS, which occurs in the presence of hydrobromic acid (with or without indium present), has been investigated by use of a new combined atomization equipment, molecular absorption measurements and thermodynamic calculations. The results show that all these elements form easily volatile bromides and more or less stable diatomic molecules of MBr type. These diatomic molecules, formed in the gaseous phase, are removed from the observation volume by diffusion, before their dissociation is complete. These two effects-formation of easily volatile compounds and stable diatomic molecules-are the main reasons for the depression of the atomic-absorption signals.     

Extraction-photometric determination of indium in zinc-base alloys with bromopyrogallol red

The extraction-photometric determination of indium at the 5 p.p.m. level in highpurity zinc and zinc-base alloys is described. After a preliminary separation of indium by isopropyl ether extraction from hydrobromic acid medium, indium is determined by extraction into benzyl alcohol of its complex with bromopyrogallol red at pH 9.0. It is shown that 2:1, 1:1 and 1:2 complexes can be formed in aqueous and water-ethanol media; the 1:3 complex reported earlier was not found. The composition of the complexes extracted into benzyl alcohol from aqueous solutions at pH 6.5 and 9.0, was found to be 1:2.