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  • 1
    Electronic Resource
    Electronic Resource
    A stable isotope method for the quantification of N-acetyl-5-aminosalicylic acid in plasma and urine (1984)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1984), S. 539-544 
    Details
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of a number of N-acyl-5-aminosalicylic acids and their derivatives is described. These compounds allow the sensitive and specific mass spectrometric determination of unlabelled or deuterium-labelled N-acetyl-5-aminosalicylic acid in biological samples. An in vivo study shows that the labelled compound, administered to rats, is excreted isotopically unchanged to at least 97%, and that no significant deacety lation/acetylation mechanism exists for this metabolite N-acetyl-5-aminosalicylic acid of salicylazosulphapyridine.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200111009
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    Paper (German National Licenses)
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  • 2
    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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    Paper (German National Licenses)
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  • 3
    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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  • 4
    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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  • 5
    Electronic Resource
    Electronic Resource
    Determination of the enantiomers of flecainide and two major metabolites in man by gas chromatography/mass spectrometry using negative ion chemical ionization and stable isotope labelled internal standards (1990)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 19 (1990), S. 256-266 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The class I antiarrhythmic drug flecainide (1) is used clinically as racemate. In order to study the stereochemical disposition and excretion of 1 an analytical method has been developed based on a deuterated analogue of 1 as internal standard and on measurement with gas chromatography/mass spectrometry (GC/MS) using negative ion chemical ionization (NICI). Several diasteromeric derivatives prepared were separated on an achiral capillary column. All derivatives exhibited negative ion properties forming characteristic fragments: [M — CH2CF3]- and [M — HF]-., respectively. The limit of detection was 1 pmol ml-1 plasma corresponding to 0.41 ng ml-1 of free base. A more convenient and in particular more precise approach was investigated by separating the pentafluoropropionyl (PFP) derivatives on a chiral phase capillary column monitoring the base peak [M — 20]-. in NICI mode. This method is not only the most sensitive assay of 1 presently available, but also allows for the determination of the enantiomers of flecainide in biological fluids. In addition, the assay could be applied to the dtermination of the enantiomers of one of the major metabolites of flecainide, the meta-O-dealkylated flecainide (MODF), in human urine. Additionally, a non-sterospecific assay was developed and applied to the quantification of the two major metabolites of flecainide, MODF and the meta-O-dealkylated flecainide lactam in human urine. Deuterated analogues were used as internal standards and measurement of the PFP derivatives with GC/MS using NICI was performed.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200190410
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