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  • 1
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Zirconium trace analyses play an important role for polyolefins produced by modern catalytic processes with zirconium metallocenes. A reliable and fast routine testing method by inductively coupled plasma isotope dilution mass spectrometry (ICP-IDMS) was therefore developed, which allows the determination of zirconium in polymers down to the low ng/g level. With respect to its precision, accuracy, and time-consumption this method is suitable for routine testing of production processes. A spike solution, enriched in the stable isotope 91Zr, was prepared and used for the isotope dilution procedure, which has the advantage of being an internal “one point” calibration method. The polyolefin samples were dissolved by microwave assisted digestion with a mixture of concentrated HNO3/HF.
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  • 4
    ISSN: 1432-0517
    Keywords: Key words Trace elements ; Water ; Intercomparison ; Comparability ; Traceability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract  The sixth round of the International Measurement Evaluation Programme (IMEP) is presented. The programme offers reference values, established by primary methods of measurement, against which participating laboratories can evaluate their performance. The degree of comparability is thus established against the most objective references available at present. In IMEP-6, reference values for total concentrations of 14 trace elements in a synthetic and a natural water were established mainly by isotope dilution mass spectrometry (IDMS). For the majority of the measurands, results traceable to the international system of units (SI) and having expanded uncertainties, U (k=2), of 2% could be established. Measurements results from 165 field laboratories in 29 countries are evaluated and presented as descriptive (regional, national and intercontinental) pictures of the participants' self-declared degree of experience, status of accreditation, performance (including target values for uncertainty set by authorities) and instrumental methods used. The participants' use of certified reference materials and calibrants has been documented, and some comments on this matter are raised. The results and characteristics for IMEP-6 are compared with those of IMEP-3 (1991–1993) and discussed in view of the forthcoming IMEP-9 (1998).
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  • 5
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
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  • 6
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
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  • 7
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Four different samples of aerosol particles over the North Atlantic, South Atlantic, an area near the equator influenced by Saharan mineral dust, and the Antarctic Ocean were collected on board of the German research vessel “Polarstern” by a six stage cascade impactor system. A continental sample, typical in its size distribution pattern and heavy metal enrichment factors (relative to crust material) for industrialized areas, was used for comparison. To analyse the elements of interest, isotope dilution mass spectrometry (IDMS) using the thermal ionization technique was applied. The samples were digested with nitric acid followed by an electrodeposition of the heavy metals to be analysed in alkaline solution. Source identification could be carried out by the distribution of the heavy metals and enrichment factors on the different impactor stages using iron as a reference element for crustal origin. Two opposite types of size distribution patterns were obtained over the Atlantic Ocean. On the one hand, the main heavy metal fraction was found to be associated with the smallest particles collected on the last two impactor stages and the back-up filter with aerodynamic diameters (AD) of less than 0.95 μm. This pattern together with the high enrichment factors of up to several thousand indicates combustion processes and biogenic emissions as possible sources and were typical for cadmium and lead. On the other hand, chromium and iron were preferably associated with the larger particles of 〉1.5 μm AD. This and the low chromium enrichment factor demonstrate that the earth crust is the major source for these two elements in marine aerosol particles. Thallium and nickel could not be classified by one of these two size distribution patterns, which indicates that at least two different primary sources contribute to the content of these heavy metals in marine aerosol particles depending on the region investigated. Contrary to that, the sample collected over the Antarctic Ocean showed some significant differences. Here, a substantial amount of the total cadmium and lead was associated with the larger particles. However, relatively high enrichment factors found for cadmium, nickel, lead, and thallium in the smallest particles suggest a natural source, probably biogenic activities, in the Antarctic Ocean.
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  • 8
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Bei Erzeugung negativer Thermionen im Massenspektrometer wird eine Meßtechnik zur genauen Isotopenverhältnisbestimmung 129I/127I entwickelt. Die Anwendung der Isotopenverdünnungsanalyse unter Verwendung eines Indicators, der an dem langlebigen radioaktiven 129I-Isotop angereichert ist, ermöglicht in diesem Zusammenhang auch eine vergleichsweise richtige Iodspurenbestimmung mit dem Massenspektrometer. In verschiedenen, handelsüblichen Speisesalzen sowie in zwei Reinchemikalien werden Iodspuren mit der massenspektrometrischen Isotopenverdünnungsanalyse bestimmt, wobei relative Standardabweichungen von etwa 1,5 % im unteren ppm-Bereich erreicht werden. Die Nachweisgrenze des beschriebenen Verfahrens, welches die Summe aller anorganischen Iodspecies erfaßt, liegt bei 6 ppb. Die zum analytischen Vergleich durchgeführten Bestimmungen mit einer iodidselektiven Elektrode zeigen gute Übereinstimmung der Ergebnisse. Die chemische Abtrennung des Iodidions geschieht mit der Anionenaustausch-Chromatographie.
    Notes: Summary A technique for a precise isotope ratio measurement of 129I/127I is developed in the mass spectrometer by negative thermal ionization. The application of the isotope dilution technique using a spike which is enriched in the longlived radioactive 129I isotope opens the possibility for an accurate iodine trace analysis by mass spectrometry. Different commercially available table salts as well as two pure chemicals are determined for iodine traces by mass spectrometric isotope dilution analysis. Relative standard deviations of about 1.5 % are obtained in the lower ppmrange. The detection limit of this method which analyses the sum of all inorganic species is 6 ppb. For an analytical comparison the same samples are analysed using an iodideselective electrode. The results agree well with the mass spectrometric values. The chemical separation of the iodide ion is carried out by anion-exchange chromatography.
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  • 9
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Es wird ein Verfahren der massenspektrometrischen Isotopenverdünnungsanalyse sowie eine Messung mit ionenselektiver Elektrode nach chromatographischer Abtrennung zur Bromid-Spurenbestimmung in geologischen Proben beschrieben. Während für erstgenannte Methode ein saurer Aufschluß mit HF Verwendung findet, wird beim zweiten Verfahren ein alkalischer Schmelzaufschluß mit einer Na2CO3/ZnO-Mischung benutzt. Für die Isotopenverhältnismessung79Br/81Br werden negative Thermionen im Massenspektrometer erzeugt. Anhand der Analyse einiger geochemischer Standards des „Centre de Recherches Pétrographiques et Géochimiques“ ergibt sich eine sehr gute Übereinstimmung beider Verfahren im unteren ppm-Bereich. Dabei ist die Isotopenverdünnungstechnik besonders als Eichmethode geeignet.
    Notes: Summary Methods for the determination of bromide traces in geological samples with isotope dilution mass spectrometry and with an ion-selective electrode after chromatographic separation are described. For the mass spectrometric method, an acidic decomposition of the sample with HF is carried out, for the electrochemical analysis the sample is melted in a mixture of Na2CO3/ZnO. The isotope ratio79Br/81Br is determined by producing negative thermal ions in the mass spectrometer. Analyses of some geochemical standards from the “Centre de Recherches Pétrographiques et Géochimiques” show very good agreement in the lower ppm range with both methods. The isotope dilution technique is especially suitable as a calibration method.
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  • 10
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Es wird ein Analysenverfahren der massenspektrometrischen Isotopenverdünnungsanalyse beschrieben, mit welchem eine gleichzeitige Bestimmung von Blei, Cadmium und Thallium in Wasserproben bis in den ppt-Bereich hinein möglich ist. Als definitive Methode ist dieses Verfahren vor allem für die Eichung anderer Methoden von Vorteil. Zur Abtrennung der analysierten Schwermetalle wird eine kathodische Elektrodeposition benutzt, während für die Isotopenverdünnung ein aus 206Pb, 116Cd und 203Tl bestehender Indicator verwendet wird. Positive Thermionen werden bei steigender Bandtemperatur in einer Einband-Ionenquelle zur aufeinanderfolgenden Messung der Elemente im Massenspektrometer erzeugt. Der Beitrag unterschiedlicher Reinheitsgrade von Chemikalien zum Blindwert des Verfahrens wurde untersucht. Verschiedene Quellwasserproben in Abhängigkeit vom Bodenuntergrund wurden analysiert. Bei der Bestimmung von Trinkwasserproben wurde ein deutlicher Konzentrationsunterschied der Schwermetalle in Abhängigkeit vom Benutzungsgrad der Wasserleitung festgestellt, wobei sich Thallium als diesbezüglich besonders empfindlicher Indicator erweist. Weiterhin wurde für Blei und Cadmium gefunden, daß diese beiden Elemente im Gegensatz zu Thallium in hohem Maße an kleinen, im Trinkwasser teilweise enthaltenen Partikeln gebunden sind bzw. von einem Quarzgefäß stark adsorbiert werden.
    Notes: Summary An analytical procedure by isotope dilution mass spectrometry for the simultaneous determination of lead, cadmium and thallium traces in water samples down to the ppt-level is described. As a definitive method this type of analysis is especially advantageous to calibrate other analytical methods. A cathodic electrodeposition is used for the separation of the analysed heavy metals. A spike solution containing 206Pb, 116Cd and 203Tl is applied for the isotope dilution technique. Positive thermal ions of the elements are successively measured by increasing the temperature of the filament in a single-filament ion source. The blank contribution of chemicals of different degree of purity for the analytical procedure was investigated. Different spring water samples dependent on the type of soil were analysed. Drinking water samples showed a significant difference in the heavy metal concentration dependent on the frequency in which the water-pipe was used. In this case, thallium is an especially sensitive indicator. It has been found for lead and cadmium that in contrast to thallium a high portion of both elements is fixed at small particles which can be included in the drinking water or is adsorbed at the surface of a quartz vessel.
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