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  • Chemistry  (4)
  • 1985-1989  (4)
  • 1
    Electronic Resource
    Electronic Resource
    Stereoselectivity of the 4-hydroxylation of debrisoquine in man, detected by gas chromatography/mass spectrometry1 (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 63-66 
    Details
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A stable isotope assay for the quantification of debrisoquine (1) and its major urinary metabolite 4-hydroxydebrisoquine (2) is described. The method consists of extractive derivatization of 1 and 2 by use of 1,3-diketones, chiral derivatization of the 4-hydroxy group of 2, and gas chromatography/negative ion chemical ionization mass spectrometry in the presence of deuterated analogues of 1 and 2. In comparison with synthetic R-(-)-2 and S-(+)-2 it is shown that in vivo benzylic 4-hydroxylation of 1 is highly stereoselective, leading predominantly to S-(+)-4-hydroxydebrisoquine (enantiomeric excess ≥90%).
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200150202
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  • 2
    Electronic Resource
    Electronic Resource
    Simultaneous determination of 6-oxo-prosta-glandin F1α and 2,3-dinor-6-oxo-prostaglandin F1α in biological fluids by stable isotope dilution and negative ion chemical ionization mass spectrometry (1985)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 12 (1985), S. 399-404 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A stable isotope dilution assay for the simultaneous determination of two metabolites of prostacyclin (1), 6-oxoprostaglandin F1α (2a) and 2,3-dinor-6-oxo-prostaglandin F1α (3a), in human seminal fluid and human urine is described. A new chemical total synthesis of deuterated internal standard, 18,18,19,19-(2H4)-2,3-dinor-6-oxo-PGF1α (3b), is presented and enables specific and sensitive quantification based on negative ion chemical ionization mass spectrometry. 2a and 3a were analysed as their methoxime pentafluorobenzyl ester tris(trimethylsilyl) ether derivatives in the selected ion monitoring mode registrating the [M-181]- fragments with a detection limit for both prostanoids of 10 pg per injection. The two metabolites occur in human seminal fluid in very low concentrations (2a: 2.8 ng ml-1; 3a: 1.7 ng ml-1) and cannot contribute significantly to the urinary metabolite levels which are in the range of 108-265 ng/24 h for 3a and 124-574 ng/24 h for 2a.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200120808
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  • 3
    Electronic Resource
    Electronic Resource
    Measurement of thromboxane B2 in human urine by isotope dilution and negative ion chemical ionization mass spectrometry (1985)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 12 (1985), S. 554-559 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A highly sensitive and specific assay for the quantification of thromboxane B2 (TXB2) (1) in human urine is described. The method is based on the use of low-blank (1H≤0.2%) tetradeuterated internal standard 2 (18, 18, 19, 19-2H4-thromboxane B2), whose chemical synthesis is reported. After purification and high-performance liquid chromatography (HPLC) samples are derivatized to give an open-chain derivative of thromboxane B2, the methoxime pentafluorobenzyl ester tris(trimethylsilyl) ether (TXB2-MO-PFB-TMS3), most suitable for negative ion chemical ionization mass spectrometry. In the selected ion monitoring mode limits of detection per injection for pure standards and biological samples of 10 pg and 30 pg, respectively, are established. Normal urinary excretion of 1 in humans is 37-112 ng/24 h (n = 12).
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200120919
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  • 4
    Electronic Resource
    Electronic Resource
    Quantification of nitrendipine by stable isotope dilution and electron-capture negative ion chemical ionization (1986)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 13 (1986), S. 645-650 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electron-capture properties of nitrendipine, a 1,4-dihydro-pyridine derivative with antihypertensive activity, have been applied to develop a sensitive and specific assay in biological fluids using capillary column gas chromatography and measurement in negative ion chemical ionization mode. The synthesis of a 13C4-labelled analogue suitable as a biological internal standard for bioavailability studies and of a 2H8-labelled analogue, which serves as internal standard, is described. The electron-capture positive ion chemical ionization and electron-capture negative ion chemical ionization mass spectra of nitrendipine and its isotope-labelled analogues are compared. The assay has a detection limit of 100 pg ml-1 plasma with a coefficient of variation of 10.2% using the selected ion monitoring mode and electron-capture negative ion chemical ionization. The method is specific, sensitive and accurate to determine terminal half-life times after intravenous and oral administration of nitrendipine and its 13C-analogue. From the nearly identical plasma concentration-time profile of nitrendipine and its 13C-labelled analogue, an isotopic effect can be excluded. Thus, the synthesized 13C4-analogue should be well suited as a biological standard for bioavailability studies.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200131202
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