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  • Analytical Chemistry and Spectroscopy  (12)
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 692-694 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Electrospray mass spectrometry has been applied to ionic inorganic systems such as heteropolyacids in methanol + water (1/1) or acetonitrile + water (1/1) solutions. Negative-ion mass spectra were obtained on four different heteropolyacids. Heteropolymolybdates H3PMo12O40 and H4PMo11VO40 and heteropolytungstates H3PW12O40 and H4SiW12O40 gave ions with different charges. H3PMo12O40 gave ions of m/z 1822, 912 and 608 which correspond respectively to [PMo12O403- + 2H+], [PMo12O403- + H+]2- and [PMo12O40]3- ions. Resolution of 1:2200 has demonstrated the charge of each ion acquired. Furthermore, the isotope distribution of the observed ions was in good agreement with theory. Thus, electrospray mass spectrometry has become a powerful soft ionization technique for the analysis of such ionic compounds, provided they are soluble and stable in the solvent system used.
    Additional Material: 7 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 9 (1995), S. 225-229 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Different compositions of micrometric particles of powdered iron oxides (Fe1-xO, Fe3O4 and Fe2O3) are examined by time-of-flight laser microprobe mass spectrometry. The positive-ion cluster distributions show a strong correlation with the stoichiometry of iron in the oxide. This correlation is more striking when the resonant process of iron at 293.7 nm is used. The bond dissociation energy of Fe--O in the bulk Fe1-xO also affects the intensity distributions. It is very important to study and to identify the iron oxides because they could play a role in the toxicity of certain molecules which could be removed on the oxides.
    Additional Material: 5 Ill.
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  • 3
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Until the present, analysis of aqueous solutions of atrazine has been conducted using a combination of liquid chromatography or gas chromatography with mass spectrometry, after a preconcentration step. We explore herein a new approach for studying support-phase-extracted atrazine and hydroxyatrazine samples. Solid-phase extraction membranes are inserted directly into the cell of a Fourier-transform mass spectrometer for analysis after laser ionization. It appears that atrazine and its metabolite have very different ionization processes. In the case of hydroxyatrazine, the [M + H]+ ion signal can be correlated to the concentration of the extracted solution. These encouraging results might open the route to a quantification method.
    Additional Material: 4 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 2 (1988), S. 146-150 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The feasibility is reported of coupling a laser microprobe sampling system with a Fourier transform mass spectrometer (FTMS) for surface characterization. Analysis of an integrated circuit chip demonstrates capabilities for focusing the laser on a selected spot on a sample surface. Analysis of a model glass sample for which high resolution is required to separate metal ions from metal oxide ions emphasizes the advantages of coupling such a sampling system to an FTMS instrument.
    Additional Material: 7 Ill.
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  • 5
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Low energy collision induced dissociation (CID) spectra indicate that m/z 173 ions formed by the loss of a halogen atom from diethyl chloro- and bromo-succinate under electron impact are mixtures of O-protonated diethyl maleate (〉90%) and fumarate (〈10 %). Hydrogen migration precedes the C-halogen bond cleavage in these cases. The low energy CID spectrum of the m/z 173 [M—I]+ ion obtained from diethyl iodosuccinate shows that only a small fraction of the [M—I]+ ions are the O-protonated species formed by hydrogen migration. The results of this study demonstrate the potential of low energy CID in the determination of structure (including configuration) of gas phase ions.
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  • 6
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 2 (1970), S. 71-78 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Interpretation of the NMR spectra of the isomeric 2-cyano-2-alkyl-5-norbornenes allowed the assignment of their respective structures. In the case of the 2-cyano-2-methyl-5-norbornene the structure assignment was confirmed by chemical synthesis (alkaline hydrolysis and iodo-lactonisation).
    Notes: L'attribution de structure des deux isomères cyano-2 alcoyl-2 norbornène-5 est possible grǎce aux données de la RMN. Une interprétation des spectres de ces dérivés bicycliques set donnée. Dans le cas des cyano-2 méthyl-2 norbornènes-5 une confirmation de structure a pu ětre donnée par voie chimique (hydrolyse basique et iodolactonisation).
    Additional Material: 2 Tab.
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  • 7
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The fast tautomeric equilibrium of (N15)-4-phenylisoxazolin-5-one (2) has been investigated by a study of 2J(N15—H3) coupling. Comparison of the observed values for 2 and for the two fixed forms (N15)-2-methyl-4-phenylisoxazolin-5-one (3) and (N15)-4-phenyl-5-methoxyisoxazol (4) indicates a considerable amount of enolic type structure for 2 in basic media.
    Notes: La comparasion des constantes de couplage 2J(N15—H3) présentées par la (N15)-4-phénylisoxazoline-5-one (2) et par deux de ses formes fixes, la (N15)-2-méthyl-4-phénylisoxazoline-5-one (3) et le (N15)-4-phényl-5-méthoxyisoxazole (4), indique une participation élevée de structure énolique (et/ou ionique) dans les milieux basiques.
    Additional Material: 1 Tab.
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  • 8
    ISSN: 0749-1581
    Keywords: 27 Al MAS NMR ; Quadruopolar interaction parameters ; Isotropic chemical shfits ; Spectral simulation ; Al2Ge2O7 ; LaAlGe2O7 ; Pentacoordinated aluminium environment ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Characterization by 27Al MAS NMR of two pentacoordinated environments of aluminium has been carried out in different fields and at different spinning speeds for Al2Ge2O7 and LaAlGe2O7. Complete simulations of the spectra have been performed, including computation of the individual shape and intensity of each spinning side band, which lead to the determination of both the quadrupolar interaction parameters and isotropic chemical shifts, and enable the detection of impurities in the material. The parameters determined are: .
    Additional Material: 5 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 24 (1986), S. 284-286 
    ISSN: 0749-1581
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: As an extension of previous work on simple amino acids, deuterium nuclear relaxation rates were used to study the molecular dynamics of γ-2,2-[2H2]aminobutyric acid, d,l-2-[2H1]glutamic acid and d,l-2-[2H1]lysine, and also model compounds 2,2,2-[2H3]acetic acid and 1,1-[2H2]butylamine. This study was carried out in aqueous solution in the pH range ca 0-14. From the observed rotational correlation times and solution viscosities, molecular volumes of various ionic forms were calculated using the Gierer and Wirtz model. The results obtained are in good agreement with conformational changes expected in the pH range investigated.
    Additional Material: 3 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 25 (1987), S. 16-20 
    ISSN: 0749-1581
    Keywords: 13C NMR ; 13C Relaxation Times ; Prototropic equilibria ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Quaternary 13C dipole-dipole spin-lattice relaxation times are used to analyse prototropic equilibria of 2-acetylbenzimidazole (1) and 4-azabenzimidazole in DMSO-d6 solutions. For the first compound, fast exchange between the two chelated structures prevails for 13C relaxation times, whereas proton and 13C chemical shifts characterize a slow exchange. For 4-azabenzimidazole, 13C and 1H spectra do not exhibit absorptions from structures in slow exchange. Analysis of the T1 values of carbons 8 and 9 before and after isotopic exchange of the labile amino hydrogen clearly show that the major component of the equilibrium is the 3H structure.
    Additional Material: 5 Ill.
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