Determination of scandium in sea-water by atomic-absorption spectroscopy

A method for the determination of scandium in sea-water at the sub-microgram level has been developed. Scandium is coprecipitated with iron(III) hydroxide at pH 8-9, and then separated from the iron by ion-exchange. The final concentration is achieved by extracting the scandium into a solution of oxine in butanol. A nitrous oxide-acetylene flame is used for the determination by atomic-absorption spectroscopy. Recoveries of 99-100% are obtained. The storage of the solutions before analysis has been investigated by radiometric techniques with (46)Sc. The scandium concentration in surface waters of the South China Sea was found to be 0.01 +/- 0.005 microg/l .     

Determination of lead in stainless steel by atomic-absorption spectroscopy

A method has been developed for the determination of lead in stainless steels by atomic-absorption spectrometry after removal of iron by solvent extraction and volatilization of chromium as chromyl chloride. The method proposed is suitable for the determination of lead in the range from 5 to 100 ppm.     

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 nanogram amounts of nickel by flameless atomic-absorption spectroscopy

A simple flameless atomizer, made from a heated graphite resistor, was investigated for the determination of nickel in various salts. The parameters characterizing its behaviour were optimized, to yield an absolute detection limit of 0.1 ng of nickel.     

Determination of sub microgram amounts of selenium in rocks by atomic-absorption spectroscopy

Atomic-absorption spectroscopy was used to determine trace amounts of selenium accurately in U.S. Geological Survey standard rocks, GSP-1, W-1 and BCR-1. The results obtained were compared with those obtained by neutron-activation analysis and excellent agreement was found; in addition, the selenium:sulphur ratio was calculated and agreed with results obtained by other workers.     

Determination of tin in poly(vinyl chloride) by atomic-absorption spectroscopy

A simple procedure is described for the determination of tin in PVC by atomic-absorption spectroscopy with an air-hydrogen flame, after wet digestion of the sample with sulphuric acid and hydrogen peroxide.     

Determination of subnanogram amounts of chromium in different matrices by flameless atomic-absorption spectroscopy

A carbon rod flameless atomizer is used for the determination of Cr in water, sea-water, sugar, glycine and blood. The reported analytical curves show that the quantitative determination of Cr in these matrices is feasible in the ppM-ppm range. The influence of the most common anionic and cationic interferents is reported.     

Determination of silicone fluid surfactants in polyurethane/polyether blends by atomic-absorption spectroscopy

A method for the atomic-absorption determination of silicone fluid surfactants present in some polyurethane/polyether blends is described. The silicone fluid in the pure state, or in the presence of polyurethane blend, is diluted with a solvent and sprayed into the nitrous oxide/acetylene flame. The effects of solvent, instrumental conditions, time and presence of the polyurethane blends were investigated. Polyurethane/polyether blends do not interfere with the silicon absorption when the samples are dissolved in aqueous ethanol (1:1) and sprayed into a fuel-rich flame.     

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.     

Determination of indium in aluminium alloys by flame atomic-absorption spectroscopy and flame atomic-emission spectrometry

The use of flame atomic-absorption and atomic-emission spectrometry for the determination of indium in aluminium alloys is described. Two types of flame are used: air—acetylene and nitrous oxide—acetylene. The efrect of other ions, especially aluminium, has been studied, and the use of lanthanum as a releasing agent is proposed for both techniques, the amount used depending on the amount of aluminium present.     

The separation of iridium and ruthenium by ion flotation

Mixtures of iridium(IV) and ruthenium(III) as IrCl^2?₆ and RuCl^t—₆ are separated by ion flotation. Iridium (IV) is selectively floated from mixtures of the metal complexes in aqueous 1.0 M hydrochloric acid with hexadecylpyridinium bromide (HPB) and nitrogen. Ruthenium(III) does not float under the same conditions. In order to assess the usefulness of this procedure, the separation was also investigated with hexadecyltrimethylammonium bromide and hexadecyltripropylammonium bromide, from solutions of varying concentrations of sodium chloride, sodium nitrite and hydrochloric acid. Under optimal conditions at the 5 × 10^?5 M level, 78% of the iridium is recovered free of ruthenium, provided that excess of HPB and > 1 M chloride are present.     

Determination of gold in geological samples at parts per milliard levels by flameless atomic-absorption spectroscopy

Summary A method is described for the determination of gold at ppM levels in geological materials by the use of flameless A. A. spectroscopy. The gold is separated as bromoaurate from HBr solution by methyl isobutyl ketone (MIBK). The MIBK phase is pipetted directly into an HGA-2000 Graphite Furnace. Detection limits of about 0.6–0.8 ppM Au for a 1-g sample are achieved. The error of determination (relative standard deviation) varies in the range 5–50%, depending on the absolute gold level.

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Zusammenfassung Ein Verfahren zur Bestimmung von ppM-Mengen Gold in geologischem Material mit Hilfe der flammenlosen Atomarabsorption wurde beschrieben. Dabei wird das Gold als Bromoaurat aus bromwasserstoffsaurer Lösung mit Methylisobutylketon extrahiert. Die organische Phase wird unmittelbar in einen HGA-2000 Graphitofen pipettiert. Die Nachweisgrenze beträgt etwa 0,6–0,8 ppM Au in einer 1-g-Einwaage. Die relative Standardabweichung variiert je nach der absoluten Goldmenge zwischen 5 und 50%.

     

Determination of lead in drinking waters by hydride generation and atomic-absorption spectroscopy, and three other methods

Simultaneous presence of copper and nickel in potable waters interferes with the determination of lead at trace levels by the hydride-atomic-absorption spectrophotometric method. This interference is eliminated by co-precipitating lead with manganese dioxide from acidic solution. The precipitate is dissolved in 0.85% nitric acid and analysed by the automated hydride-atomic-absorption method. This method has been applied to 22 representative water samples and results compared with those obtained by using differential pulse anodic-stripping voltammetry, flame atomic-absorption and graphite-furnace atomic-absorption spectrophotometry. The precision of the three methods is reported and their accuracy checked by the analysis of reference standard water samples. The sensitivity of the three methods is of the order of 1 mug/l., compared to 100 mug/l. for flame atomic-absorption. The merits of each method are discussed.     

Determination of molybdenum by atomic-absorption spectrophotometry

A new procedure is described for precise estimation of molybdenum by atomic-absorption spectrophotometry using an airacetylene flame. Phosphoric acid was found to be effective in suppressing interference by Fe(III), Al, Sb(III), Ca, Mg, Pb and Mn(II).     

Determination of mercury by atomic-absorption spectrophotometry

A flameless atomic-absorption system has been developed for the determination of low concentrations of mercury in gaseous, solid and liquid samples of organic and inorganic materials.     

Determination of cadmium by atomic-fluorescence and atomic-absorption spectrophotometry

The adaptation of a conventional atomic-absorption/flameemission spectrophotometer to the measurement of atomic-fluorescence in an air-acetylene flame is described. The determination of cadmium on the same instrument by both atomic-fluorescence and absorption shows that, even with a rather simple and inefficient means of exciting and measuring fluorescence, results can be obtained which indicate that the fluorescence technique is considerably more sensitive than atomic-absorbance and is equally free from inter-element interference.