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.     

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.     

The use of long-chain alkylamines for preconcentration of traces of molybdenum, tungsten and rhenium in their determination by atomic-absorption spectroscopy-I General studies

Long-chain alkylamines are used for the preconcentration of traces of molybdenum, tungsten and rhenium as thiocyanate complexes, in their determination by atomic-absorption spectroscopy. General studies of factors, influencing the extraction show that the thiocyanate complexes can be extracted into chloroform containing a low concentration of Amberlite LA1. Detection limits are 0.02 ppm Mo, 0.75 ppm W and 0.34 ppm Re in the final MIBK solution and are improved by a factor of 5-10 over those obtained by using current extraction methods. Serious interelement effects are eliminated and a range of other cations and anions are shown to have little effect on the absorption.     

Atomic-absorption spectrophotometric determination of traces of manganese with thenoyltrifluoroacetone

An atomic-absorption spectrophotometric method for the determination of traces of manganese in solution with thenoyltrifluoroacetone (TTA) is described. Manganese(II) is extracted with 0.01M TTA in methyl isobutyl ketone (MIBK) at pH 9.5. The atomic-absorption of the organic phase at 279.5 nm is measured. Except for chromium, iron, hafnium, niobium, nickel, rhodium, tin, titanium and zirconium, microquantities of many other cations and anions do not interfere. Iron can be removed by MIBK extraction before the TTA extraction. The sensitivity of the method was 1.6 ng/ml for 1% absorption in aqueous solution. The method was successfully applied to the analysis of environmental waters. Manganese in the filtered fractions of water samples was reliably determined with relative standard deviations of 7% at the 5 mug/l. level and 1% at 50 mug/l.     

Determination of silver in copper and lead metals and alloys and in zinc and selenium by atomic-absorption spectrometry after separation by extraction of the tri-n-octylmethylammonium-silver bromide complex

A simple and sensitive combined solvent extraction and atomic-absorption spectrometric method has been developed for the determination of silver in copper and lead metals and alloys and in zinc and selenium. Optimal conditions have been established for the extraction and determination of silver. Silver is extracted as the tri-n-octylmethylammonium-silver bromide complex and determined by atomic-absorption spectrometry by spraying the extract directly into the flame. As little as 0.2 mug of silver in a sample can be determined.     

Determination of traces of Mo in soils and geological materials by solvent extraction of the molybdenum-thiocyanate complex and atomic absorption

Comprehensive studies of the extraction of the molybdenum-thiocyanate complex with methyl isobutyl ketone have resulted in an improved method for the determination of traces of molybdenum in soils and geological materials by atomic-absorption spectroscopy. The method is applicable in the range 1-500 ppm Mo, with 1-g samples, giving relative standard deviations not exceeding about 8% at a level of 1 ppm. The limit of detection is 0.1 ppm. There are few interferences, and large quantities of iron are without effect.     

Determination of trace amounts of scandium by atomic absorption spectroscopy

Optimum instrumental conditions were investigated for the determination of trace quantities of scandium by atomic-absorption spectroscopy. Enhancement effects by organic solvents and by complex extractions were also studied. (46)Sc was used to establish the optimum extraction conditions. A sensitivity of 0.06 ppm of Sc was observed when using extraction into oxine-butanol and atomic absorption was measured with an acetylene-nitrous oxide flame.     

Determination of lanthanides and yttrium in rocks and minerals by atomic-absorption and flame-emission spectrometry

The sensitivity of atomic-absorption and flame-emission determination of lanthanides and yttrium is improved by a factor of 2-5 when an absolute ethanol solution of the perchlorate of the metal (instead of an aqueous solution) is aspirated into a nitrous oxide-acetylene flame. Based on this, a method has been developed for accurate determination of small amounts of certain rare earths and yttrium. Lanthanum (1%) is used as a spectroscopic buffer to eliminate interferences and to enhance the sensitivities in certain determinations. Where the use of lanthanum is not practicable because of interferences (such as in the determination of praseodymium and samarium by flame emission), sodium (2000 ppm) is used as the spectroscopic buffer. Studies with synthetic solutions indicate that yttrium and most lanthanides can be directly determined in minerals without any chemical separation. With rock samples it is necessary to preconcentrate the traces of the rare earths by fluoride or oxalate precipitation with calcium as the carrier, followed by removal of calcium by hydroxide precipitation using mg amounts of iron as the carrier. The method developed has been applied to the determination of certain lanthanides and yttrium in a variety of rocks, including the Canadian reference rocks, syenites SY-1, SY-2 and SY-3, and some minerals such as britholite, cenosite, chevkinite, allanite, apatite and sphene.     

Optimization of the determination of selenium by atomic-absorption spectrometry: Comparison of two hydride generation systems

Two commercially available systems for the determination of selenium by hydride-generation and atomic-absorption spectrometry were compared. Chemical and physical parameters were optimized both for an electrothermally heated closed atom-cell method and a flame-heated open-cell technique. Both systems were evaluated with respect to performance and applicability to determination of traces of selenium.     

Determination of trace levels of calcium in steels by carbon-furnace atomic-absorption and atomic-emission spectrometry

Methods are described for the determination of trace levels of calcium in steels by atomic-absorption and atomic-emission spectrometry with a carbon furnace for atomization and excitation. In both cases, a commercial electrothermal atomic-absorption instrument was used. Samples were analysed after dissolution in a mixture of nitric, hydrochloric, and hydrofluoric acids.     

Indirect atomic-absorption determination of boron by solvent extraction as tris(1,10-phenanthroline)cadmium tetrafluoroborate

An indirect atomic-absorption method for boron has been developed. Boric acid is converted into tetrafluoroborate and extracted into nitrobenzene with Tris(1,10-phenanthroline)cadmium(II). The cadmium in the extract is determined by its atomic-absorption at 228s>d8 nm. A fivefold molar excess of the cadmium chelate is necessary for the extraction from pH 4>d3-6>d0 medium. The sensitivity for boron is thus made about the same as that of cadmium, 0>d005 ppm. Metal ions that react with fluoride or phenanthroline interfere. A procedure is described for determination of boron in steel.     

Atomic-Absorption Determination of Zinc in Water with Micellar-Extraction Preconcentration with Phases of Nonionic Surfactants

Effects of various factors on the extraction of zinc with carboxylic acids and their mixtures with amines into a micellar phase of a nonionic surfactant at the cloud point were studied. The conditions for the atomic-absorption determination of zinc preconcentrated into an OP-10 phase on heating with capric acid and n-octylamine were developed.     

Improved tribenzylamine-silver bromide extraction/atomic-absorption spectrophotometric method for the determination of silver in ores, related materials and zinc process solutions

An improved tribenzylamine extraction/atomic-absorption method for the determination of silver in ores, related materials and zinc process solutions is described. The method, which involves the separation of silver by a single methyl isobutyl ketone extraction of the tribenzylamine-silver bromide ion-association complex from ~ 0.5-2M sulphuric acid-0.14M potassium bromide, is simpler and more rapid than a previous method based on a triple chloroform extraction of the complex. Silver is stripped with 12M hydrochloric acid containing 1% thiourea as a complexing agent. Thiourea is destroyed with nitric and perchloric acids and silver is ultimately determined by atomic-absorption spectrophotometry in an air-acetylene flame, at 328.1 nm, in a 10% v v hydrochloric acid-1% v v diethylenetriamine medium. Cadmium and bismuth are partly co-extracted but do not interfere. Results obtained by this method are compared with those obtained previously by the tribenzylamine/chloroform extraction method and with those obtained by a direct acid-decomposition/atomic-absorption method.     

An investigation of a flameless atomic-absorption method for determination of aluminium, calcium, iron and magnesium in sewage sludge

The methods currently used for the determination of aluminium, calcium, iron and magnesium in sewage sludge are time-consuming. A rapid flameless atomic-absorption procedure, utilizing homogenization of diluted samples as the only pretreatment, has been compared with wet and dry analytical methods followed by flame atomic-absorption analysis, in a statistically designed experiment. Low-sensitivity (secondary absorption) lines have been used for the flameless analysis. The flameless atomic-absorption method described is better than all the other methods tested, with the exception of the nitric-perchloric-hydrofluoric acid digestion procedure. The time saved is substantial and the method could be used advantageously for routine analysis.     

Determination of traces of calcium, magnesium, iron and nickel in aluminium salts by atomic-absorption spectrophotometry with a microwave-excited source and hollow-cathode lamps

The determination of trace amounts of calcium and magnesium in solutions containing large concentrations of aluminium salts may be accomplished by co-precipitating their hydroxides on iron(III) hydroxide, dissolving the precipitate, and extracting the 8-hydroxyquinolates of calcium and magnesium into methyl isobutyl ketone at about pH 11. The extract may be sprayed into the airpropane flame of a simple unmodulated spectrophotometer and atomic-absorption measurements for calcium and magnesium made at 4227 and 2852 A respectively. The limits of determination correspond to 10 and 1 ppm of calcium and magnesium in solid alumina. Iron and nickel may be co-precipitated on hydrated manganese(IV) oxide and their 8-hydroxyquinolates extracted at pH 4.5. Measurements of atomic absorption for these elements at 2483 and 2320 A respectively yield limits of determination corresponding to 10 ppm in alumina. Hollow-cathode lamps may be used for calcium, magnesium and nickel, but a simple microwave-excited discharge tube gives much better sensitivity than a hollow-cathode lamp for iron.     

APDC-MIBK extraction system for the determination of trace elements in saline waters by atomic-absorption spectrophotometry

A technique has been developed for the determination of "soluble" cobalt, copper, iron, lead, nickel and zinc in saline waters by simultaneous extraction of their complexes with ammonium pyrollidine dithiocarbamate (APDC) into methyl isobutyl ketone (MIBK) and subsequent analysis by atomic-absorption spectrophotometry. Particulate matter is analysed separately by dissolving millipore filters in an acetone-hydrochloric acid mixture. Various analytical and instrumental parameters have been evaluated. The method is selfcompensating in that it makes allowance for any incomplete extraction of the complexes. The technique has been applied to the determination of these elements in sea-water and saline lakes.     

Ultramicro atomic-absorption spectroscopy with a tungsten-filament atom-reservoir

The detection and measurement of traces of zinc, lead, copper and silver by atomic-absorption spectroscopy, with a tungsten-filament atom-reservoir (TFAR), hollow-cathode lamps and limited-field viewing is described. The performance of this atom cell is compared with that of the carbon-filament atom-reservoir for determination of lead. Greater sensitivity and fewer matrix effects are observed with the TFAR system. The lifetime of the tungsten filament is almost indefinite.     

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 tungsten in rocks and minerals by chelate extraction and atomic-absorption spectrometry

An atomic-absorption method for determination of tungsten in rocks and minerals is proposed. The method involves sample decomposition by acid digestion or by pyrosulphate fusion, followed by chelate extraction of tungsten by N-benzoylphenylhydroxylamine in toluene. Atomic-absorption measurements are made on the organic phase aspirated into a nitrous oxide-acetylene flame. Quantitative extraction with efficient separation from other elements is achieved in a single extraction from strong acid media. The method is rapid and reliable in terms of precision and accuracy and is applicable to rocks and minerals containing tungsten in the range from 100 ppm to 15%.