Cupferron separation for the determination of tantalum in high-purity iron and low alloy steel by ICP-AES

For the determination of Ta (> 0.0005 mass %) in iron and low-alloy steel spectrophotometric methods, e.g., after the extraction of the Ta-Victoria Blue B complex by benzene, are generally used. To avoid the application of poisonous benzene as extracting solvent and to improve the detection power, an ICP-AES method after the separation of Ta by coprecipitation with cupferron has been developed. The detection limit (3σ) of 0.6 μgTa/g is lower in comparison with spectrophotometric methods. Therefore, the method also allows the determination of Ta-concentrations in the μg/g-range in high-purity iron.     

Cupferron separation for the determination of tantalum in high-purity iron and low alloy steel by ICP-AES

For the determination of Ta (> 0.0005 mass %) in iron and low-alloy steel spectrophotometric methods, e.g., after the extraction of the Ta-Victoria Blue B complex by benzene, are generally used. To avoid the application of poisonous benzene as extracting solvent and to improve the detection power, an ICP-AES method after the separation of Ta by coprecipitation with cupferron has been developed. The detection limit (3σ) of 0.6 μgTa/g is lower in comparison with spectrophotometric methods. Therefore, the method also allows the determination of Ta-concentrations in the μg/g-range in high-purity iron. Received: 26 February 1998 / Revised: 4 May 1998 / Accepted: 10 May 1998     

Ultratrace analysis of uranium and thorium in glass

Three methods of determination for uranium and thorium traces and ultratraces in glass were developed: a simple and powerful ICP-MS method exhibiting limits of determination in the one ng/g-range; a complex method with end-determination by classical photometry and a limit of determination for U and Th of 20 ng/g; and a method with chelate-complex formation for U and Th and subsequent GC-detection with a ⁶³Ni-ECD with limits of determination in the g/g-range. These methods are critically compared and tested for real type samples of special glasses.Abbreviations used AAS Atomic absorption spectrophotometry - ECD Electron capture detector - FOD 1,1,1,2,2,3,3-Heptafluoro-7,7-dimethyl-4,6-octanedion - GC Gas chromatography - HFA 1,1,1,5,5,5-Hexafluoro-2,4-pentanedione - ICP-AES, -MS Inductively coupled plasma-atomic emission spectrometry, metry, -mass spectrometry - LAS Liquid absorption spectrophotometry = classical photometry - NAA Neutron activation analysis - NIST National Institute of Standardization and Technology (Gaithersburg, U.S.A.) - TBP Tri-(n-butyl)-phosphate - TFA 1,1,1-Trifluoro-2,4-pentanedione - TTFA 1-(2-Thenoyl)-3,3,3-trifluoroacetone - XRS X-ray (fluorescence) spectrometry     

Spurenbestimmung von organisch gebundenem Schwefel und Chlor in kleinen Probenmengen

Summary A rather simple device is described for mineralizing organic liquids for the determination of sulfur, chlorine, and other halogenides. The detection of the mineralization products of these elements, e.g. chloric acid or sulfuric acid, is done by ion chromatography with high-sensitive suppressor technique. For the determination in the g/g-range samples of 0.1 to 1 ml are required. Detection limits are lower than 1 g/g.     

Hydraulic high-pressure nebulization sample introduction for direct analysis or on-line matrix separation and trace preconcentration in flame AAS

Summary Only by replacement of the pneumatic nebulization by the new hydraulic high-pressure nebulization (HHPN) in flame AAS 2 to 10 times higher power of detection (depending on the element) can be achieved for the direct trace determination in a saturated tungstate solution. HHP-nebulization leads in general to higher sensitivity and additionally to lower matrix interferences. The HHPN-sample introduction system offers also facilities for a quick on-line matrix separation/trace preconcentration. Detection limits of 0.1 to 1 g/g were achieved for a tungsten matrix (depending on the element).     

Atomic absorption spectrometric determination of mercury in soil standard reference material following microwave sample pretreatment

Several decomposition procedures and their influence on the determination of mercury by electrothermal (ET) and cold vapour (CV) atomic absorption spectrometry (AAS) have been studied. Soil samples were decomposed by microwave digestion in closed and open vessels as well as by digestion under reflux according to German standard. The use of different acids (HNO₃, HCl or aqua regia) was evaluated and compared in respect to their influence on the determination of mercury by ET AAS and CV AAS. The digestion solutions were analyzed by ET AAS with a palladium modifier and by CV AAS using SnCl₂ or NaBH₄, as reducing agents. The detection limits obtained with different procedures were also evaluated. For the soil containing 6.25 g/g of Hg the ET AAS measurements were possible. In the case of lower concentration of mercury the CV AAS determination following the microwave digestion procedure with HCl or aqua regia is recommended. The accuracy of the proposed procedure was confirmed by the determination of total mercury in SRM 2711 Montana Soil.On leave from: Institut für Analytische Chemie, Technische Universitat Wien, Getreidemarkt 9, A-1060 Wien, Austria     

Zur Multi-Elementanreicherung aus eisenhaltigen B?den und Sedimenten

Summary Traces of Ag, Bi, Cd, Co, Cu, Hg, In, Mo, Ni, Pb, Se, and Zn can be preconcentrated with recoveries R_s 95% from soils and sediments of high iron content by collector precipitation with hexamethylene-ammonium-hexamethylenedithiocarbamate and with a small amount of the iron as a collector element. The trace concentrates are analyzed by AAS and XRF. The relative standard deviation of the combined method of sample decomposition, preconcentration and AAS determination (n = 12) is generally about 0.03; the limit of detection (3 s, n = 20) for different elements was found to be between 0.1 and 1 g·g^–1. The accuracy of the method was verified by certified standard material. The power of detection of XRF for the analysis of trace concentrates obtained from soils and sediments is only sufficient for some of the interesting elements.     

Trace determination of molybdenum and vanadium in natural waters by means of atomic spectroscopy (AAS, ICP-OES) after preconcentration

Conclusions Mo and V are abundant trace elements in the environment and of great significance for many organisms [1]. Their accurate and precise determination in natural waters by means of AAS and ICP-OES often requires a separation and/or a pre-concentration step. For the reliable and simple separation of Mo and V in the ng/l- to g/l-range, the co-precipitation on Cell-Fe and Cell-In can be applied with good reproducibility. By coupling with atomic spectroscopy, analytical procedures result for ultratrace determination of Mo and V, even in complex water matrices or biological fluids (e.g., urine).

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Atomspektroskopische Bestimmung (AAS, ICP-OES) von Molybdän- und Vanadium-Spuren in natürlichen Wässern nach Voranreicherung

     

Analysis of microgramme samples from a sputtering crater by Atomsource excited atomic absorption spectrometry

Summary Additional application work has been carried out in order to demonstrate further possibilities of the combination Atomsource/AAS for the determination of trace elements in microgramme samples. The method was tested in routine application for different elements like Cu, Nb or Zr. Moreover, a very simple method of mercury determination allowing the detection of 1 ng Hg in 1 g sample material is described. The technique permits direct analysis of dust, soil, and other oxide samples collected in microgramme amounts for several elements.     

The determination of platinum in biotic and environmental materials,I. μg/kg- to g/kg-range

A simple and reliable procedure for the determination of platinum including high pressure ashing, separation and detection by graphite furnace AAS has been developed. It was put to practical use in the analysis of biotic and environmental materials polluted with platinum in the concentration rangeg/kg to g/kg.     

Sample introduction assisted by compressed air in flame furnace AAS: a simple and sensitive method for the determination of traces of toxic elements

The power of detection of flame AAS for the toxic elements Cd, Hg, Pb and Tl can be improved by 1–2 orders of magnitude by using flame furnace AAS. In flame-furnace AAS, liquid samples are introduced directly into a nickel tube located in the flame, in the simplest case through a ceramic thermospray capillary. Transportation of the samples is achieved by using compressed air only. Comparatively low detection limits are achieved by both beam injection flame furnace (BIFF-AAS) and thermospray flame furnace AAS (TS-FF-AAS). For TS-FF-AAS, a pressure of less than 20 kPa (<80 in. water) is required. The TS-FF-AAS technique is very simple, robust and cheap. The detection limits were 0.2–0.4 g L^–1 (Cd), 40–100 g L^–1 (Hg), 5–9 g L^–1 (Pb) and 4–14 g L^–1 (Tl), respectively, depending on the method, flow rate and sample volume used. Pb and Cd were found at concentrations of 0.1–2 and 0.005–0.3 g g^–1, respectively, in samples of various spices.Dedicated to the memory of Wilhelm Fresenius.     

Determination of trace impurities in electronic grade quartz: Comparison of inductively coupled plasma mass spectroscopy with other analytical techniques

An analytical procedure for the determination of uranium and thorium in the sub-ng/g range as well as of other trace elements in the ng/g to g/g range in high purity quartz samples is described. The results obtained by inductively coupled plasma mass spectroscopy (ICP-MS) are compared to those obtained by other analytical techniques (instrumental neutron activation analysis, INAA; flame atomic absorption spectrometry, AAS; Zeeman graphite furnace atomic absorption spectrometry, ZGFAAS; total reflection X-ray fluorescence analysis, TRFA; direct current arc optical emission spectrometry, DC-arc OES; and X-ray fluorescence analysis, XRFA). For the ICP-MS measurements, the decomposition of the samples is carried out with HF/HNO₃/H₂SO₄-mixtures. The results obtained by the different methods show reasonable agreement. For uranium and thorium, ICP-MS proves to be the most sensitive method: detection limits of about 50 pg/g can be achieved for both elements.Presented in part at the 1989 European Winter Conference on Plasma Spectrochemistry, Reutte, Austria     

A microbatch anion-exchange technique for matrix separation

Summary A rapid and simple one-vessel microbatch anionexchange method has been developed for matrix separation prior to the AAS determination of the trace elements. The method can be applied to the separation of matrix elements which are strongly sorbed on anion exchangers, e.g. gold, palladium, bismuth a.o. The method was illustrated by the flame or ET-AAS determination of 20 trace elements in pure gold. The limits of detection were from 0.002 to 0.4 g/g, the RSD from 3 to 8% depending on the trace element.     

Testing and Determination of Iron(II, III) as an Adsorbate of Iron(II) Phenanthrolinate by Chromaticity Measurements

It was demonstrated that cation exchangers of different nature can be used for the sorption preconcentration of iron(II) as phenanthrolinate and its determination in the adsorbent phase by diffuse reflectance spectrometry and chromaticity measurements. A procedure was developed for the determination of iron in solutions with a detection limit of 2.5 g/L. A scale was proposed for the visual determination of iron(II) at concentrations down to 0.4 g/L. The test procedure was verified using water samples from the Severnaya Dvina estuary and Dvinskii Bay taken during the summer and winter periods in 2000–2001.     

Determination of Iron in Caco-2 cells by ET-AAS

An electrothermal atomic absorption spectrometric method (ET-AAS) was developed for the direct determination of iron in intestinal Caco-2 cells after studying cell viability and proliferation using 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyl tetrazolium bromide (MTT test). Zeeman background correction and end-capped graphite tubes with Lvov platforms were used. Samples were dissolved in dimethylsulfoxide (DMSO) and pipetted directly into the graphite tube. The preashing, pretreatment and atomization steps were optimized. The temperatures selected were 600, 1200, and 2100 °C, respectively. Stability measurements were performed using iron standard solutions in DMSO on the one hand and acidified cell solutions on the other. Direct measurement and standard addition were compared in order to determine possible influences of the matrix. The low detection limit of the ET-AAS method (1.3 g/L or 3.3 g/g) combined with the small sample quantities required are ideal for the determination of iron in cells due to the low iron content and the limited growth area of the cells. The method was developed for iron uptake studies for toxicological purposes.     

Efficiency of four different techniques in coupled HPLC-UV/VIS to quantify overlapping peaks with known spectral features

Summary Four different techniques to quantify unresolved chromatographic peaks with known spectral features combined with photodiode array detection, are investigated as regards their efficiency for the accurate and precise determination of drugs in the low g-range. The comparison includes peak suppression utilising difference chromatograms, first-order derivative chromatograms, selective chromatograms, generated by the calculation of orthogonal polynomial shares, and the powerful least-squares multicomponent analysis approach. Each of these methods uses UV-spectra taken throughout, the peak. The results presented and conclusions reached should enable the chromatographer to come to a decision about the reasonable use of these options now provided by multichannel detection in HPLC.     

Bestimmung von Gold im ppm- bis ppb-Bereich in Selen und Erzen mittels AAS nach Anreicherung durch Extraktion und Adsorption

Zusammenfassung In einem einfachen Verbundverfahren werden ppm- und ppb-Gehalte von Gold entweder nach Extraktion mit Methacrylsäuremethylester (MME) direkt im ppm-Bereich mittels Flammen-AAS oder im ppb-Bereich nach Absorption an selenorganische Verbindungen in der Graphitküvette bestimmt. Die Nachweisgrenze in der Flammen-AAS ist 0,2 g Au/ml MME; in der Graphitküvette können noch 0.25 ng nachgewiesen werden. Die relative Standardabweichungen für die Goldbestimmungen sind bei Gehalten von 0,064 ppm in Selen 23%, bei 14 ppm 3,5%; in Bleikonzentraten bei 0,41 ppm 10,2%. Das angegebene Verfahren ist auf Erze und andere Metallkonzentrate übertragbar.

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AAS Determination of gold in the ppm to ppb range in selenium after enrichment by extraction and adsorption

Summary With a simple method ppm and ppb amounts of gold were determined either after extraction with methyl methacrylate (MME) directly by flame AAS in ppm amounts or after absorption on organoselenium compounds in ppb amounts with flameless AAS. The determination limit by flame AAS is 0.2 g Au/ml MME, by flameless AAS 0.25 ng. The relative standard deviations for the determination of gold are 23% for the determination in selenium in the range of 0.064 ppm, in the range of 14 ppm 3.5%. For lead concentrates with 0.41 ppm the relative standard deviation is 10.2%. This method may be used, too, for the analysis of other metal concentrates and ores.

Für die Gewährung eines Stipendiums (L.F.) danken wir der Alexander von Humboldt-Stiftung.     

Simultaneous flow injection speciation of iron(II) and iron(III) cyano complexes utilizing electrochemical and atomic absorption detectors in series

Summary A method is described for the simultaneous speciation of Fe(CN) ₆ ^4– and Fe(CN) ₆ ^3– in a flow injection (FIA) system comprising electrochemical (EC) and flame atomic absorption spectrometry (AAS) detectors in series. One of these species is detected amperometrically at a Pt-electrode by applying the required potential and measuring the resulting reduction or oxidation current of the appropriate iron cyanide complex. Total iron in both species is determined by an AAS detector. The EC detector is inherently more sensitive, with a detection limit of 0.5 g Fe l^–1 and a relative standard deviation of 1.0% for a 0.040 g Fe ml^–1 sample. The limit of detection for the AAS detector is 0.5 g Fe ml^–1, and the relative standard deviation for a 5.70 g Fe ml^–1 sample is 0.40%. The method enables up to 60 analyses (120 speciations) per hour and obviates the problem of easy oxidation of Fe(CN) ₆ ^4– .

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Simultane Speziation von Eisen(II)- und Eisen(III)-Cyanokomplexen durch Flie\injektionsanalyse mit Hilfe von hintereinander geschalteten elektrochemischen und AAS-Detektoren

     

Determination of vanadium in biological matrices by flame atomic absorption spectrometry with activated carbon enrichment

For the determination of vanadium in biological materials by flame AAS an enrichment is described which comprises chelation with oxine and adsorption on activated carbon: The relative standard deviation for 10 g V/L was found to be 6% (n=15).Dedicated to Professor Dr. Dieter Klockow on the occasion of his 60th birthday     

Determination of beryllium in plants by means of flameless atomic absorption with zirconium-coated and non-coated graphite tubes

Summary After removing the major part of the matrix elements and other accompanying ions from the digested plants by an extraction with acetylacetone/methylisobutyl-ketone in presence of EDTA, subsequently followed by a reextraction with nitric acid, this element can be determined interference-free by means of flameless atomic absorption with non-coated and zirconium-coated graphite tubes as electrothermal atomizers. During the above mentioned extraction-reextraction procedure only very small amounts of aluminium and iron are coextracted and did not interfere with the determination of beryllium. Recovery analyses confirmed that the whole analytical procedure was quantitative. The detection limit of beryllium was found to be 1.5 g/l reextract. As an example, roots, stems and leaves of Calluna vulgaris were analyzed.

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Bestimmung von Beryllium in Pflanzen durch flammenlose AAS unter Verwendung von Graphitrohren mit und ohne Zr-Beschichtung