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  • 1
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A gas chromatographic-mass spectrometric (GC/MS) method for analysis of Δ1-tetrahydrocannabinol (Δ1-THC) in human fat samples is described. The fat sample, obtained from heavy marihuana users 1 week before and 4 weeks after smoking, is homogenized in hexane + 2-propanol, centrifuged, and the supernatant mixed with Lipidex 5000. The solvent is evaporated and the dried gel is packed in a glass column. Δ1 -THC is eluted from the column with methanol + water + acetic acid, diluted with water and the eluent is passed through a bed of Octadecylsilanebonded silica. After washing and drying, the retained Δ1-THC is eluted with hexane, derivatized with N-methyl-N-(t-butyl-dimethysilyl)trifluoroacetamide (MTBSTFA) and finally purified by HPLC on an Octadecyl SI 100 column in methanol. The amount of Δ1-THC is determined by GC/MS, using selected ion monitoring, and a deuterated internal standard. The recovery of Δ1-THC is about 80%, and the concentration of Δ1-THC in the fat samples analysed ranged between 0.4 and 193 ng/g wet tissue.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 7 (1995), S. 272-277 
    ISSN: 0899-0042
    Keywords: local anaesthetics ; enantiomers ; stereoselective ; liquid chromatography ; Chiral AGP column ; bioanalysis ; urine samples ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ropivacaine hydrochloride monohydrate (ropivacaine) is a new local anaesthetic agent which is administered exclusively as the (-)-(S)-form. The aim of the study was to determine whether metabolic racemisation of (-)-(S)-ropivacaine occurs. This was tested in man, rat, dog, and sheep after different routes of administration. The enantiomers of ropivacaine and two of the major metabolites, 3-hydroxy-ropivacaine and 2′,6′-pipecoloxylidide (PPX), were determined in urine samples by liquid chromatography on a Chiral AGP column after liquid-liquid extraction. It was possible to detect 〈1% of the (+)-(R)-enantiomer of both ropivacaine and the two major metabolites. In the samples examined, no trace of metabolic racemisation was observed. In pharmacokinetic, pharmacodynamic, toxicological, and metabolic studies, therefore, nonchiral assays are considered to be adequate. © 1995 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 13 (1986), S. 287-291 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: As part of our efforts to characterize the in vivo metabolic fate of the antihypertensive agent α-methyldopa, we have examined the urine of α-methyldopa-treated rats with the aid of a direct insertion probe chemical ionization mass spectral assay. The mass spectrum of the sample obtained by chromatographic purification followed by treatment with ethanolic hydrochloric acid and pentafluoropropionic anhydride displayed an intense ion at m/z 812, consistent with the β-ethoxy-N,O,O,O-tetrakispentafluoropropionyl derivative of 6-hydroxy-α-methyl-norepinephrine, a potential aromatic hydroxylation product of the known α-methyldopa metabolite α-methyl-norepinephrine. Comparison of this spectrum with the spectrum obtained with the corresponding synthetic 6-hydroxy-α-methylnorepinephrine, however, ruled out this possibility. A more thorough examination of the mass spectral data established that the ion at m/z 812 observed with the metabolic species was due to the formation of an unexpected adduct ion between a known metabolite of α-methyldopa and an impurity ion formed from a common constituent of urine. This paper summarizes the characterization of this adduct ion.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 299 (1959), S. 122-137 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The reactions between hydrogen sulfite and hydroxylamine-N-monosulfonate or -N-disulfonate are branched ones, yielding about 70% imidodisulfonate and 30% amidosulfonate or 70% nitridotrisulfonate and 30% imidodisulfonate.The reaction velocities are proportional to the concentrations of sulfonate and hydrogen sulfite.The activation energies in the temperature range from 25 to 60°C are 24.5 and 18.0 kcals/mol, the A-factors are 1.2 · 1015 and 4.3 · 1011 1/mol · min, respectively. Osulfinic acids are assumed to be intermediate products.
    Notes: Die Umsetzungen von Hydroxylamin-N-monosulfonat und -N-disulfonat mit Hydrogensulfit sind gegabelte Reaktionen, die zu etwa 70% zu Imidodisulfonat bzw. Nitridotrisulfonat und zu 30% zu Amidosulfonat bzw. Imidodisulfonat führen. Die Geschwindigkeit des Stoffumsatzes ist proportional der Konzentration des Sulfonats und des Hydrogensulfits. Die ARRHENIUsschen Aktivierungsenergien im Temperaturbereich von 25 bis 60°C sind 24,5 bzw. 18,0 kcal/Mol, die A-Faktoren 1,2 · 1015 bzw. 4,3 · 1011 1/Mol · min. Wahrscheinlich sind Zwischenprodukte der Umsetzungen O-Sulfinsäuren, deren innermolekulare Umlagerung und Hydrolyse die Reaktionsgabelung verursachen.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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