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  • Analytical Chemistry and Spectroscopy  (1)
  • tetramethylarsonium  (1)
  • Wiley-Blackwell  (2)
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  • Wiley-Blackwell  (2)
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  • 1
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 20 (1985), S. 476-478 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Conditions have been established for the detection by chemical ionization mass spectrometry (CIMS) of compounds related to L-dopa (3-hydroxy-L-tyrosine) and L-tryptophan without derivatization. The least fragmentation of the parent ion occurs in positive ion CIMS when methylamine is used as reagent gas. The compounds can also be detected by negative ion CIMS using carbon tetrachloride as reagent gas. While the total ion current in the latter technique is lower than that obtained with positive ion CIMS, the background noise in the mass spectra of samples obtained from natural sources is greatly reduced. CIMS has been used to show the presence of aromatic amino acids in acid extracts of samples of two different classes of tumour without sample derivatization.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0268-2605
    Keywords: halophytes ; arsenobetaine ; arsenocholine ; tetramethylarsonium ; arsenosugars ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Five species of halophytes were sampled in the salt marshes of the Tagus estuary, dried, ground and digested. They were further extracted with ethanol and the extracts passed through weak and strong cationic ion-exchange resins, purified through TLC and submitted to pyrolysis mass spectrometry and HPLC-ICP/MS. Arsenic content and hydride-forming arsenic species were verified, in each step, by GF-AA and HG-QFAA. A high content of arsenic was found in the samples of halophytes studied, both di- and tri-methylated arsenic compounds being present. A considerable fraction of this arsenic content seems to be refractory to hydride generation. Moreover, the arsenic fraction found seems to have the same ion-exchange behaviour as the refractory fractions formerly studied in estuarine water.A partial characterization of these structures by pyrolysis-GC-MS suggests the presence of arsenobetaine and arsenocholine compounds. Furthermore, HPLC-ICP/MS data seem to confirm the presence of these compounds. In addition, the latter hyphenated technique strongly suggests the presence of a number of other organoarsenicals including tetramethylarsonium (TMAs), trimethylarsine oxide (TMAO), cacodylate (DMA) and possibly an arsenosugar-type compound. © 1997 by John Wiley & Sons, Ltd.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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