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  • 1985-1989  (9)
  • 1
    Digitale Medien
    Digitale Medien
    Study of a system for introducing metal chelate complexes in AAS (1988)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 332 (1988), S. 37-40 
    Details
    ISSN: 1618-2650
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The possibility of extending the sampling of volatile phases in AAS by use of metal beta-diketonates is considered. An electrically heated system was designed in which the chelate was injected, volatilized and then carried by a nitrogen stream to a silica tube, which was heated with an air-acetylene flame. The method was investigated for Cr, Zn and Mn using acetylacetone as chelating agent. The introduction of volatile chelates gives an increase in sensitivity with respect to the nebulization and atomization of solutions in the flame. This sampling system is limited to metallic chelates which are thermally stable and sufficiently volatile. The partial decomposition, which Zn acetyl-acetonate and, particularly Mn acetylacetonate undergo, causes a reduction in the sensitivity and precision of the determination.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00487027
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  • 2
    Digitale Medien
    Digitale Medien
    Some observations on the mechanisms for stabilization of chromium in graphite furnace-atomic absorption spectrometry (1988)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 332 (1988), S. 783-786 
    Details
    ISSN: 1618-2650
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Graphite atomization mechanisms of chromium in a graphite furnace are briefly reviewed and the influence of some compounds on stabilization of the analyte is investigated. For this purpose, charring curves for various salts and solvents were obtained. Elements which from stable oxides stabilize chromium oxide, avoiding losses of the volatile suboxide. Elements which form carbides and the organic solvents depress the signal due to the formation of chromium carbide.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01129775
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  • 3
    Digitale Medien
    Digitale Medien
    Determination of chromium by AAS using volatileβ-diketonate complexes (1987)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 328 (1987), S. 56-60 
    Details
    ISSN: 1618-2650
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A new method is proposed for the determination of chromium, which is based on atomizing the volatile phase, generated from itsβ-diketonates, in a silica tube. For this purpose, an electrically-heated volatilization system was designed, in which the chelate is injected and volatilized, and then carried by nitrogen to the silica tube, which is heated with an air-acetylene flame. The system parameters were optimized and the analytical characteristics established, the following values being obtained: characteristic mass (measuring area under peak) 0.15 ng, reproducibility (expressed as the relative standard deviation) 5.6%, and linearity up to 25 ng. The results obtained were compared with those found when atomizing solutions ofβ-diketonates in an air-acetylene flame and in a graphite furnace. Atomization of chromiumβ-diketonates (after first volatilizing them) increases the sensitivity 54-fold as compared with the nebulization of aqueous solutions of dichromate with atomization in the flame.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00560948
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  • 4
    Digitale Medien
    Digitale Medien
    Direct flame atomic absorption spectrometry — Volatile covalent hydride generation (1986)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 325 (1986), S. 171-174 
    Details
    ISSN: 1618-2650
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Summary Optimum for the generation of arsine from As(III) and (V) in a generating system without carrier gas and with atomization in an air-acetylene flame were established. A 3% solution of NaBH4 was used as reducer. The effect of 26 different species on the determination of arsenic was studied. The method has been applied to determine arsenic in copper. A linear relationship exists between 0.5 and 3 μg for As(III) and between 1 and 4 total μg of As(V). The sensitivity, expressed as the slope of the calibration curve is 0.067 μg−1 for As(III) and 0.054 μg−1 for As(V); the characteristic masses are 1.22 μg and 0.44 μg, and the limits of detection 0.27 μg and 0.33 μg, respectively.
    Notizen: Zusammenfassung Optimale Bedingungen wurden ausgearbeitet für die Arsinerzeugung aus As(III) und As(V) in einem System ohne Trägergas mit Atomisierung in einer Luft-Acetylen-Flamme. Zur Reduktion dient eine 3%ige NaBH4-Lösung. Der Einfluß von 26 Fremdionen wurde geprüft und das Verfahren zur Arsenbestimmung in Kupfer angewendet. Eine lineare Beziehung ergab sich für 0,5–3 μg As(III) und 1–4 μg As(V). Die Empfindlichkeit (als Neigung der Eichkurve) beträgt 0,067 μg−1 für As(III) und 0,054 μg−1 für As(V). Die charakteristischen Massen sind 1,22 μg bzw. 0,44 μg und die Nachweisgrenzen 0,27 μg bzw. 0,33 μg.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00468883
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  • 5
    Digitale Medien
    Digitale Medien
    Determination of ytterbium by AES-ICP. Application to samples of biological origin (1988)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 331 (1988), S. 721-724 
    Details
    ISSN: 1618-2650
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Ytterbium is used as a marker in studies of digestion physiology in ruminants; its determination has been accomplished by Inductively Coupled Plasma — Atomic Emission Spectroscopy (ICP-AES). An analytical study has been carried out, which includes the evaluation of various emission lines (atomic, ionic). The line at 328.937 nm is proposed for determining Yb, with a limit of detection of 1.68 ×10−3μg ml−1. The analytical procedure has been applied to the determination of this element in samples of animal fodder, rumen contents and feces.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01105607
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  • 6
    Digitale Medien
    Digitale Medien
    Determination of As, Sb and Bi in high-purity copper by electrothermal atomic absorption spectrometry (1986)
    Springer
    Microchimica acta 88 (1986), S. 105-114 
    Details
    ISSN: 1436-5073
    Schlagwort(e): electrothermal AAS ; copper ; arsenic ; antimony ; bismuth
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract As, Sb and Bi were determined in copper electric cables by atomic absorption spectrometry with electrothermal atomization in a graphite furnace. The interferences in the determination of As, Sb and Bi caused by eleven cationic species and six types of acid were studied. The different volatilization of the copper matrix in comparison to the analyte was studied, as a means of increasing the analyte signal/non-specific absorption signal ratio.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01196692
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  • 7
    Digitale Medien
    Digitale Medien
    Influence of oxidising agents in lead determination by hydride generation direct flame atomic absorption spectroscopy (1985)
    Springer
    Microchimica acta 85 (1985), S. 253-263 
    Details
    ISSN: 1436-5073
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Es wird über den Einfluß der Oxidantien Cr2O7, MnO4 −, Ce4+, H2O2 und S2O8 2 − auf die Bleibestimmung als kovalentes Hydrid berichtet. Für jede oxidierende Substanz werden die Reaktionsbedingungen optimiert (pH, Menge und Konzentration des Oxidans, Menge und Konzentration von NaBH4 und Reaktionszeit), um Empfindlichkeit und Nachweisgrenze durch Peakhöhenauswertung zu bestimmen. Die Wiederfindungsrate wurde durch elektrothermale Atomabsorptionsspektrometrie von Blei in der Lösung bestimmt. Der Zusammenhang zwischen dem Logarithmus der Extinktion und dem Redoxpotential des Oxidans ergibt eine lineare Beziehung mit einem Korrelationskoeffizienten von 0.999. Die Ergebnisse und deren Interpretation werden in dieser Arbeit beschrieben.
    Notizen: Summary The influence of Cr2O7 2−, MnO4 −, Ce4+, H2O2 and S2O8 2− as oxidising agents in lead determination as volatile covalent hydride using NaBH4 is reported in this paper. The reaction conditions for every oxidising agents (pH, quantity and concentration of the oxidising agent, quantity and concentration of the NaBH4 and reaction time) are optimized, determining sensitivity and detection limit by measuring the peak height. The recovery of lead from solution has been measured by flameless atomic absorption spectroscopy. A linear relationship the logarithm of absorbance values and the redox potential of the system is obtained with a correlation coefficient of 0.999. The results and their interpretation are given in this paper.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01198298
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  • 8
    Digitale Medien
    Digitale Medien
    Volatile phase introduction of metallic beta-diketonates in atomic absorption spectrometry: Zinc acetylacetonate (1986)
    Springer
    Microchimica acta 90 (1986), S. 407-416 
    Details
    ISSN: 1436-5073
    Schlagwort(e): atomic absorption spectrometry ; volatile phase ; zinc determination ; beta-diketonates
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The combined method volatile phase-atomic spectroscopy is an improvement in comparison with the conventional method of liquid sample introduction. The generation of a volatile phase by sublimation from an ethanolic solution of zinc acetylacetonate monohydrate and the obtainment of an analytical signal by AAS is proposed in this paper. The volatile phase is introduced in a silica tube by means of a nitrogen stream as carrier gas. The proposed method gives an improved sensitivity of 6.2 times with respect to the introduction of the same sample in liquid phase and more than 30 times with respect to the introduction of the zinc as chloride in aqueous solution.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01199281
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  • 9
    Digitale Medien
    Digitale Medien
    Speciation of antimony by differential generation of its volatile covalent hydride in aqueous and organic phase (1986)
    Springer
    Microchimica acta 90 (1986), S. 95-103 
    Details
    ISSN: 1436-5073
    Schlagwort(e): antimony ; speciation ; hydride generation ; AAS
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract By using the ammonium pyrrolidinedithiocarbamate (APDC) — methylisobutyl ketone (MIBK) extraction system Sb(III) is extracted into the organic phase. Sb(III) is directly determined in this organic phase by hydride generation AAS using NaBH4/dimethylformamide solution as reducing agent. Sb(V) is determined in the aqueous phase using the same technique.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01196824
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