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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 3802-3805 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Low-field (〈1 kV/cm) switching has been investigated for thin plates (0.06〈d〈0.15 cm) of triglycine sulfate by means of field pulses with a linear rise time. The dependence of the maximum current density, jm, with the field value Em at which this maximum occurs is jm≅B1(Em−Ecw1)3/2, for 0.3〈Em〈0.5 kV/cm, and jm≅B2(Em−Ecw2), for 0.5〈Em〈1.0 kV/cm. This is satisfactorily explained taking into account the dominant role played by sidewise and forward domain wall motion, respectively. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract  Chromatographic effluents were on-line analyzed by Zeeman-ETAAS, using a flow-through cell placed in a graphite furnace autosampler as interface. To obtain high sampling rates, the use of fast graphite furnace programmes was studied. Conventional programmes of 96 s were reduced to 18 s by using hot injection (120 °C) and reducing the charring step to 2 s. The increase of the injection volume from 20 to 60 μl lengthened the programme to 46 s. Nickel had to be added to get a comparable response for both inorganic and organic selenium species (selenite and selenomethionine) and to reduce the interferent effect produced in presence of the chromatographic eluent (TRIS 0.01 mol l-1, NH4NO3 0.1 mol l-1, pH 7). The optimized conditions were applied to the speciation of selenium in human erythrocyte lysates by size exclusion LC-ETAAS. Using a high performance size exclusion column selenium could be assigned to proteins of 100 and 35 kDa. Detection limits in the range of 1 ng (2 μg l-1 for 500 μl injection volume) were obtained for the combined technique.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of applied electrochemistry 28 (1997), S. 65-70 
    ISSN: 1572-8838
    Keywords: carbon paste electrode ; mediator ; electrocatalysis ; hydrazine ; cobalt complexes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Four cobalt complexes (cobalt(II) acetylacetonate and 8-hydroxyquinolinate and cobalt(III) 8-hydroxyquinolinate and diethyldithiocarbamate) were tested as mediators to modify carbon paste electrodes with a view to obtaining a catalytic effect for the hydrazine. Cobalt(II) acetylacetonate was found to exert no catalytic effect as the likely result of ligand having to stabilize higher oxidation states of Co potentially involved in the catalytic process. The effects of the electrolyte and pH were examined and found to be important. The proposed chronoamperometric determination for hydrazine features limits of detection at the 99% confidence level of 1.6mM with cobalt(III) diethyldithiocarbamate, 1.5mM with cobalt(III) 8-hydroxyquinolinate and 2.0mM with Co(II) 8-hydroxyquinolinate. The RSD for 2mM hydrazine was always less than 8%.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 332 (1988), S. 37-40 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: 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.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 332 (1988), S. 783-786 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: 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.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 328 (1987), S. 56-60 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: 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.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 325 (1986), S. 171-174 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 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.
    Notes: 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.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 331 (1988), S. 721-724 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: 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.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1436-5073
    Keywords: Keywords. Arsenic determination; flame atomic absorption; chloride volatilization; insectide sample.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract.  The generation of volatile species of As(III) as a means to introduce arsenic into a flame atomic absorption spectrometer has been studied. The method is based on the reaction between As(III) and chloride ions in sulphuric acid medium. The reaction is performed in a discontinuous or batch mode. With this method 130 μl of a solution containing 17.5% (w/v) sodium chloride and As(III) are injected by a 500 ml.min−1 N2 carrier gas flow into 1 ml of concentrated sulphuric acid. The gaseous compounds generated are introduced into the spectrometer through the nebulizer and As is determined.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1436-5073
    Keywords: electrothermal AAS ; copper ; arsenic ; antimony ; bismuth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: 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.
    Type of Medium: Electronic Resource
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