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  • Analytical Chemistry and Spectroscopy  (6)
  • Linked and unlinked diagrams  (2)
  • soils  (2)
  • 1995-1999  (10)
  • 1985-1989
  • 1995  (10)
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Verlag/Herausgeber
Erscheinungszeitraum
  • 1995-1999  (10)
  • 1985-1989
Jahr
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Microchimica acta 119 (1995), S. 251-258 
    ISSN: 1436-5073
    Schlagwort(e): extractable chromium ; soils ; EDTA extracts ; acetic acid extracts ; FAAS ; releasing agent oxine and ETAAS
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The lixiviation of trace metals from soils using selective extractants gives valuable information, especially for agricultural purposes. The two reagents validated by a group of European researchers coordinated by the Measurements and Testing Program (MAT) of the Commission of the European Community, in single extraction procedures, are EDTA 0.05 moll−1 and CH3COOH 0.43 moll−1. This paper reports the effect of these extractants upon chromium determination in extracts by AAS. Matrix effects were studied in extracts of two soils of different origin: a terra rossa soil from a Mediterranean area and a sewage amended soil. For the FAAS technique, the matrix effects were studied for air-acetylene and nitrous oxide-acetylene flames and using Cr(VI) and Cr(III) as standard solutions. The interfering effects observed are circumvented by the use of 1% 8-hydroxyquinoline as suppressor agent. For the ETAAS technique, charring and atomization curves were obtained for extracts in each reagent and after setting up the graphite furnace program, matrix effects were studied. Different matrix modifiers (Mg(NO3)2, Pd and Triton X-100) were also tested. Once the analytical method had been established, single extraction procedures were applied in the two soils, determining the percentage of extractable chromium in relation to the total content.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    ISSN: 1436-5073
    Schlagwort(e): extraction ; soils ; trace elements ; candidate CRMs ; reference materials
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The determination of extractable trace metal contents in soil using single extraction procedures is currently performed in many laboratories to assess the bioavailable metal fraction (and related phytotoxic effects) and the accessability to the environment (e.g. contamination of ground waters). Owing to the need for validation of the extraction schemes used and of the analytical techniques, the EC Measurements and Testing Programme (formerly BCR) has organized a project for improving the quality of determination of extractable trace metal contents in soil, the first step being an interlaboratory study to adopt common extraction procedures and the second being a certification campaign to certify two soils for their extractable trace element contents following these procedures. This paper gives a brief overview of the project organisation and describes the preparation, homogeneity and stability studies of two soil candidate reference materials (sewage sludge-amended and terra rossa soils).
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical chemistry accounts 92 (1995), S. 241-252 
    ISSN: 1432-2234
    Schlagwort(e): Intermediate Hamiltonians ; Total dressing ; Size-consistent configuration interactions ; Linked and unlinked diagrams ; Spectroscopic constants
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A previously proposed procedure including the linked and unlinked contributions due to Triple and Quadruple excitations into a size-consistent SDCI-like model has been applied to HF and F2 single-bond systems. The procedure is a non-iterative approximation to the more general total dressing model, which is based on the intermediate Hamiltonians theory. Three basis sets have been employed: the correlation consistent cc-pVTZ basis, a similar one including 3d1f polarization functions, and another including one set of g polarization functions. Excellent agreement with experiment and high-quality calculations is obtained for both equilibrium distances and spectroscopic constants. The possibilities of the method in treating single-bond breaking are also demonstrated. Finally, the Linked and Non-Linked contributions from Triple and Quadruple excitations are analysed separately and it is suggested that the addition of the linked triples to the size-consistent SDCI is sufficient to have quantitatively correct spectroscopic properties in going from the size-consistent SDCI to nearly experimental values.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Theoretica chimica acta 92 (1995), S. 241-252 
    ISSN: 0040-5744
    Schlagwort(e): Key words: Intermediate Hamiltonians ; Total dressing ; Size-consistent configuration interactions ; Linked and unlinked diagrams ; Spectroscopic constants
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary.  A previously proposed procedure including the linked and unlinked contributions due to Triple and Quadruple excitations into a size-consistent SDCI-like model has been applied to HF and F2 single-bond systems. The procedure is a non-iterative approximation to the more general total dressing model, which is based on the intermediate Hamiltonians theory. Three basis sets have been employed: the correlation consistent cc-pVTZ basis, a similar one including 3d1f polarization functions, and another including one set of g polarization functions. Excellent agreement with experiment and high-quality calculations is obtained for both equilibrium distances and spectroscopic constants. The possibilities of the method in treating single-bond breaking are also demonstrated. Finally, the Linked and Non-Linked contributions from Triple and Quadruple excitations are analysed separately and it is suggested that the addition of the linked triples to the size-consistent SDCI is sufficient to have quantitatively correct spectroscopic properties in going from the size-consistent SDCI to nearly experimental values.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: The electron ionization-induced fragmentation pattern of extended tetrathiafulvalenes has been studied by exact mass measurements, metastable ion analysis and collision-induced dissociation mass spectrometry. The influence on the fragmentation of the central bridge linking the dithiole moieties is discussed.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    ISSN: 1075-4261
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Physik
    Notizen: SERS, SERRS and NIR FTSERS of emodin and hypericin are reported for the first time on aqueous silver colloid. Intense SERRS spectra can be obtained when using excitation lines at 514 nm for emodin and 598 nm for hypericin. FTIR and NIR FTRaman spectra from these molecules and their model compounds, anthrone and bianthrone, were recorded to assist in the assignment of the SERS bands. From the analysis of the SERS spectra a different orientation for each molecule can be deduced. © 1995 John Wiley & Sons, Inc.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 24 (1995), S. 221-225 
    ISSN: 0049-8246
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: The synchrotron photoionization method was applied to measure L-subshell Coster-Kronig yields for Tb. This method is based on the capability of tuning the energy of the synchrotron photons producing a selective subshell ionization. A foil sample of Tb was irradiated and characteristic spectra were recorded. Data were analysed using a new formalism (based on a matrix representation) to express x-ray fluorescence intensities involving Coster-Kronig transitions. The results obtained were f12 = 0.201 ± 0.014, f13 = 0.281 ± 0.027 and f23 = 0.097 ± 0.016. These data represent valuable information for spectroscopists, considering the lack of data for L-shell parameters.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    ISSN: 0049-8246
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: A system based on the EDAX 9100 analyser was developed to obtain concentration profiles. Even though the system can be used on any type of flat specimens, in this study it was used for measuring the tungsten (W) concentration on rough spherical specimens of the W-γ-Al2O3 supported catalyst. The concentration gradient of the active component from the periphery to the centre of the particle is often an important factor in determining catalyst performance. The purpose was to determine the concentration profile of W along the radius of a sphere with a large enough number of experimental points to draw accurate information in a short time. In this way, a considerable number of impregnated spheres can be analysed, and average results can be calculated and taken as representative values of the population under study. The method developed provides highly satisfactory results, making it very useful for the systematic study of this type of specimen. Obviously, the use of this system can be extended to metallurgical and mineralogical specimens.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 33 (1995), S. 196-200 
    ISSN: 0749-1581
    Schlagwort(e): selective 2D J-resolved methods ; long-range proton-carbon coupling constants ; norbornene derivatives ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Long-range proton-carbon coupling constants, nJCH, were measured for some simple norbornene derivatives. Among the influence of substitution pattern, a study of the experimental influence of the double bond in the norbornene skeleton on 2JCH and 3JCH was made, taking into account the previously published experimental data for analogous saturated systems. These experimental data show that structural groups which are several bonds away from the coupling sites, but close in space, can provide important alternative mechanisms for transmission of the heteronuclear coupling.
    Zusätzliches Material: 3 Tab.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 26 (1995), S. 149-154 
    ISSN: 0377-0486
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: SERS spectra of cytosine, 1-methylcytosine, 5-methylcytosine and 1,5-dimethylcytosine on a gold colloid are reported. A tentative assignment of Raman bands is made by comparison with the normal Raman spectra in aqueous solution. This analysis reveals a preferred non-planar orientation of cytosine and 1-methylcytosine and a more planar orientation of 5-methylcytosine and 1,5-dimethylcytosine with respect to the metal surface, the C=O group being determinant in the interaction. A comparative study using the result obtained previously using silver and copper colloids as supports shows important differences in the electrodynamic behaviour of these molecules which depend on the presence of the methyl substituents and the nature of the metal on which they adsorb.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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