Observations on the determination of osmium by inductively-coupled plasma atomic emission spectroscopy

Osmium tetroxide gives rise to very characteristic atomic emission properties. In acidic samples it gives much higher sensitivity than that given by the lower oxidation states (IV, III, II). However, in alkaline medium (pH 10.5) its atomic emission sharply decreases, and the sensitivity is the same as that for the other oxidation states. It has been shown that there is a direct relation between these characteristics of OsO(4) solutions and pH. With increasing pH the intensity of its atomic emission decreases, the electrode potential of its solutions drops sharply and the molecular absorption of radiation at 193 nm undergoes a hyperchromic and bathochromic shift. The volatility of OsO(4) has also been studied, and found to be minimum at around pH 9.5. This favours its determination at this pH.     

Reduction of tin and germanium to hydrides for determination by inductively-coupled plasma atomic emission spectrometry

The effect of a range of acids on the reduction of tin and germanium to their hydrides in aqueous solutions by means of sodium tetrahydroborate(III) solution in a continuous flow system is investigated. Interference effects in hydrochloric acid and tartaric acid reaction media are tabulated. Tartaric acid decreases many interference effects. Detection limits for both elements are low (ca. 0.2 μg l^-1) and the linear calibration ranges span nearly four orders of magnitude.     

Microcolumn liquid chromatography with inductively-coupled plasma atomic emission spectronometric detection

Summary An ICP detector is described which is compatible with microcolumn liquid chromatography. The total column effluent is concentrically nebulized and aspirated into a plasma flame. The carbon compounds are selectively detected by monitoring the characteristic emission line at 247.9 nm using water or aqueous solutions as the mobile phase. The detection limit for carbon is 500 ng or less, and the response is linear over at least two decades. The potential of this system is illustrated by a few applications.     

A flow injection/hydride generation system for the determination of arsenic by inductively-coupled plasma atomic emission spectrometry

A flow-injection system is described for the semi-automatic determination of arsenic (10–1000 μg l^?1) by hydride generation and inductively-coupled plasma atomic emission spectrometry. The elements which were found to interfere were Co, Ni, Ag, Au, Bi, Te and Sn. Standard reference materials were analyzed with good accuracy. Approximately 200 injection h^?1 are possible. The detection limit is 1.4 ng arsenic.     

Preconcentration by dithiocarbamate extraction for determination of trace elements in natural waters by inductively-coupled plasma atomic emission spectrometry

Preconcentration by dithiocarbamate extraction into 2-ethylhexyl acetate for simultaneous determination of trace elements in natural water is described. After 250-fold concentration, the organic phase is used directly for inductively-coupled plasma atomic emission spectrometry. Thirteen elements (As, Se, Mo, Zn, Cd, Ni, Co, Sn, Fe, Cr(VI), Pb, V and Cu) are simultaneously concentrated at pH 4.3 with the combination of ammonium tetramethylenedithiocarbamate and dibenzylammonium dibenzyldithiocarbamate and are determined in the extract; Mn and Cr(III) are also determined after preconcentration at pH 6.9 with the same chelating agents. Lake waters are analyzed by this method.     

On-line preconcentration with activated carbon for microwave plasma torch atomic emission spectrometry

This paper presents a method whereby trace elements are adsorbed in NH(4)ClNH(3) medium on activated carbon and then determined by microwave plasma torch atomic emission spectrometry (MPT-AES). The working conditions (including microwave forward power, gas flow rate, NH(3)NH(4)Cl concentration in the sample solution, HCl concentration in the eluant, sample introduction rate and preconcentration time) were investigated in detail. The effects of concomitant ions were studied. The experimental results for such analytes as Pb, Mn, Cd, Cu and Fe indicate that the procedure can eliminate fundamentally the interferences caused by alkali and alkaline earth metal elements and the application of it to the determination of iron in industrial silicon and tap water samples is successful.     

Determination of phosphorus in waste-waters by inductively-coupled plasma atomic emission spectrometry

Inductively coupled plasma—atomic emission spectrometry offers a simple and rapid method for the determination of total phosphorus in waste-waters: the optimum operating conditions are described. The detection limits are 0.02, 0.04, and 0.11 μg ml^-1 at the 213.618, 214.914, and 253.565-nm lines, respectively. Interferences by other elements are negligible at the concentration levels of these elements in environmental and waste-waters, except for the spectral interference of copper on the lines at 213.618 and 214.914 nm. Differences in emission response for various inorganic and organic phosphorus compounds are small. Analytical results for phosphorus in municipal and industrial waste-waters agree well with those obtained by standard methods.     

Simultaneous determination of 14 lanthanides and yttrium in rare earth ores by inductively-coupled plasma atomic emission spectrometry

A method is described for simultaneous determination of 14 lanthanides and yttrium in monazites and xenotimes by inductively-coupled plasma atomic emission spectrometry. The ore samples were decomposed by heating with nitric acid/perchloric acid or hydrofluoric/nitric/perchloric acids, or sulfuric acid, or by fusion with sodium carbonate. Among these methods, treatment of the samples with sulfuric acid, by evaporation to dryness followed by dissolution of the residue with hydrochloric acid is recommended; it provided complete decomposition for the five monazites and xenotimes examined. The accuracy and precision of the results were significantly influenced by spectral interferences of the rare earth elements themselves; correction methods and factors are given. The chondrite-normalized rare-earth patterns were examined to characterize the monazite and xenotime samples.     

Simultaneous multielement analysis of zeolite catalysts by inductively-coupled plasma atomic emission spectrometry

Summary A method comprising digestion of zeolites with an acid mixture followed by inductively-coupled plasma atomic emission spectrometry (ICP-AES) has been established for the simultaneous determination of Al, Na, La and Si in various zeolite samples. Various aspects including sample digestion, instrumental interference effects as well as analytical performance and applicability of the established method have been investigated in detail. The results indicated that aqua regia in combination with hydrofluoric acid was effective for decomposition of a wide variety of zeolite samples. The effects of borate and fluoride ions in the digested sample solution on the ICP-AES determination have been carefully investigated. The method established will be generally applicable for the simultaneous determination of Al, Na, La and Si in zeolite with a precision of 5%. The analytical results obtained were checked by comparison with classical wet chemistry methods and found to be in reasonably good agreement. Application to the kinetic study of La-NaY exchange reaction was also performed.

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Simultane Multielementanalyse von Zeolit-Katalysatoren durch ICP-AES

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Dedicated to Prof. Dr. W. Fresenius on the occasion of his 75th birthday     

Application of hydride generation to the determination of trace concentrations of arsenic by inductively-coupled plasma atomic emission spectrometry

A method is described for the determination of traces of arsenic, based on sodium tetrahydroborate reduction of arsenic and introduction of the arsine formed to a relatively low-powered (1.6 kW) inductively-coupled plasma where the arsenic atomic emission is generated, Inter-element interference effects are described; many can be eliminated by addition of potassium iodide to the sample solutions, but the standard additions method is recommended for accurate arsenic determination. Potassium iodide is also used for prereducing arsenic(V) to arsenic(III). The method has a detection limit of 0.1 ng As ml^-1 and the linear calibration range spans nearly four orders of magnitude. The proposed method is applied to the determination of ng ml^-1 levels of arsenic in waste waters.     

Determination of cadmium by suction-flow liquid-liquid extraction combined with inductively-coupled plasma atomic emission spectrometry

The flow manifold described permits suction-flow liquid-liquid extraction of cadmium in a discrete aqueous sample as its diethyldithiocarbamate into carbon tetrachloride. The organic extract is fed into the nebulizer of an inductively-coupled plasma atomic emission spectrometer by a peristatic pump. An increase in sensitivity of ca. 250-fold is achieved in comparison with direct aspiration of the aqueous solution. The sampling frequency is 20 h^?1 and the consumption of carbon tetrachloride and 5% (w/v) sodium diethyldithiocarbamate solution are each 0.6 ml min^?1. The 3σ detection limit is 0.4 ng ml^?1 cadmium, and the calibration is linear up to 300 ng ml^?1. The relative standard deviation for 10 replicate measurements is 1.5% for 50 ng ml^?1 cadmium. The flow interferences observed can be decreased or eliminated by the addition of citrate to the buffer solution. Results of analysis of some certified biological reference materials are given.     

Simultaneous multi-element determination of trace metals in sea water by inductively-coupled plasma atomic emission spectrometry after coprecipitation with gallium

Coprecipitation with gallium hydroxide is studied for the preconcentration of trace metals in sea water before multi-element analysis by inductively-coupled plasma/atomic emission spectrometry. Gallium precipitates at pH 9 only when magnesium is present. Optimum conditions are established for multi-element preconcentration and removal of matrix elements. The method is almost free from contamination because of the use of highly pure gallium meetal and only a small amount of sodium hydroxide for pH adjustment. Spectral interferences from gallium are negligible and a concentratioin factor of more than 200 can be obtained. Detection limits range from a few ng l^?1 to 150 ng l^? for Al, Co, Cr, Fe, La, Mn, Ni, Ti, V, Zn, Y and Pb. Artificial and natural sea-water samples can be analyzed with adequate precision.     

Screening for selected toxic elements in urine by sequential-scanning inductively-coupled plasma atomic emission spectrometry

A rapid screening method for nine elements (Se, As, Cr, Zn, Cd, Pb, Ni, Mn, and Cu) in human urine is described. A sequential-scanning inductively-coupled plasma atomic emission spectrometer, incorporating a cross-flow nebulizer, was used. Internal standardization with yttrium compensated for the differences between the aqueous calibration standards and the undiluted urine specimens. Accuracy was evaluated with aqueous (NBS SRM 1643a, EPA 378-13, and EPA 476-3) and urine (NBS SRM 2670 and Fisher Urichem Level II) reference and control materials. Detection limits for the system were evaluated from analyses of normal urine materials found to contain low levels of the elements investigated.     

Comparative study for aluminum determination in bone by atomic absorption techniques and inductively coupled plasma atomic emission spectroscopy

A comparative investigation was carried out on the suitability of atomic absorption spectrometry and inductively coupled plasma atomic emission spectroscopy for aluminum determination in bone. Both techniques give reliable results but the nitrous oxide-acetylene flame method was not found to be sensitive enough to accurately measure low aluminum content. A suitable method for sample treatment is also described. Quantitation of aluminum in bone from patients on regular hemodialysis is also done.     

Determination of sulfur in biological samples by vacuum-ultraviolet inductively-coupled plasma atomic emission spectrometry

Sulfur is most sensitively determined at 180.7 nm, the detection limit being 10 μg l^?1. A comparison of digestion procedures shows that acid digestion in a teflon bomb gives least loss of analyte. Only calcium interferes spectrally at this wavelength. Results for various reference materials are presented.     

Simultaneous determination of heavy metals in waters by inductively-coupled plasma atomic emission spectrometry after extraction into diisobutyl ketone

Nebulization of more than thirty aliphatic and aromatic liquids into a low power (<1.6 kW) argon inductively-coupled plasma (i.c.p.) was evaluated. Diisobutyl ketone (DIBK) was best owing to the ease of its introduction into the i.c.p. and low aqueous solubility. Dichloro-8-quinolinol, hexamethyleneammonium hexamethylenedithiocarbamate and ammonium pyrrolidinedithiocarbamate were tested for extraction ; the last was preferred as chelating reagent because it formed complexes with Cd, Pb, Zn, Fe, Cu, Ni, Mo and V at pH 2.4. These metals at μg l^-1 levels in river and sea water were extracted into DIBK and determined simultaneously by i.c.p. atomic emission spectrometry. The optimum observation height for the DIBK extract was higher than that for an aqueous solution.     

Preconcentration and determination of trace chromium(III) by flow injection/inductively-coupled plasma/atomic emission spectrometry

A manifold incorporation an activated alumina (basic form) minicolumn is used to preconcentrate chromium(III), which is then eluted with 2 M nitric acid for detection. Calibration is linear up to 1000 μg l^? Cr, and the limit of detection for a 10-ml sample is 0.05 μg l^?1. The determination of chromium(III) in human urine is discussed.     

Sensitivity enhancement for inductively-coupled plasma atomic emission spectrometry of cadmium by suction-flow on-line ion-exchange preconcentration

A column of iminodiacetate chelating resin is used to preconcentrate cadmium by a factor of 25-fold for a 5-ml sample. The sampling rate was 25 h^?1, and the detection limit 0.05 ng Cd²⁺ ml^?1. The r.s.d. for 0.1 μg Cd²⁺ ml^?1 was 2.2% (n = 10). This technique was applied to the determination of cadmium in certified biological reference materials and waste-water samples.     

Dissolution of geological material with orthophosphoric acid for major-element determination by flame atomic-absorption spectroscopy and inductively-coupled plasma atomic-emission spectroscopy

An analytical procedure has been developed for the determination of major elements in geological material by both flame atomic-absorption spectrometry and inductively-coupled plasma atomic-emission spectrometry. Condensed phosphoric acid was used for the decomposition of 70 natural minerals containing sulphide, oxide, silicate or carbonate constituents. The results were compared with those obtained when a perchloric acid and orthophosphoric acid mixture was used for the decomposition, to ensure dissolution of even the most acid-resistant minerals. The procedure can be applied to rocks, ores, soils, slags and refractory material as a means of rapid and complete dissolution for the analysis of even the most insoluble material.     

Analytical characteristics of an optimized miniature inductively-coupled plasma source for atomic emission spectrometry

The inside dimensions of a miniature (13 mm i.d.) inductively-coupled plasma (i.c.p.) torch were optimized in an attempt to reduce further the r.f. power and argon gas required to sustain an i.c.p. As found earlier with a conventional-sized (18 mm i.d.) torch, the annular spacing between the plasma (intermediate) and coolant (outer) tube was shown to be the most critical design parameter. However, the optimized miniature i.c.p. could not necessarily be operated at lower r.f. power and argon flow rate than the optimized 18-mm torch or at lower argon flow rate than the original 13-mm torch. Moreover, although the detection limits and working-curve linearity of the optimized mini-i.c.p. were comparable to those of a conventional-sized torch, the errors caused by classical vaporization interferents were somewhat greater.