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  • Analytical Chemistry and Spectroscopy  (2,128)
  • 1970-1974  (2,128)
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  • 1
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Repetitive mass spectrometric scanning of gas-liquid chromatographic effuents at short (6 to 15 s) intervals, with a digital computer for data acquisition, reduction and display, allows plots (mass chromatograms) to be made of the intensities of specific ion fragments. Plotting of m/e values characteristic for certain classes of compounds and/or individual components reveals the location of constituents in the gas chromatogram. This technique was applied to the identification of trimethylsilyl derivatives of unsubstituted and 2-hydroxy fatty acid methyl esters in mixtures obtained from acid catalyzed methanolysis of cat brain galactocerebrosides. The plot of total ionization intensity vs scan number generated the gas-liquid chromatogram. Mass chromatograms of m/e 73 and [M - 59]+ gave the locations in the gas-liquid chromatogram of the hydroxy fatty acid derivatives, and mass chromatograms of m/e 74 and [M]+ located the unsubstituted fatty acid derivatives. Integrated ion intensities were used to determine the composition of the mixture of fatty acids.
    Additional Material: 5 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 1 (1974), S. 20-28 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Complete mass spectra of the pertimethylsilylated derivatives of three high molecular weight polyene macrolide antibiotics are reported for the first time. The fragmentation pathways which are proposed have been corroborated by the stable isotope derivatives d9-TMS and d3-acetyl. Accurate mass measurements and metastable transitions confirm the proposed fragmentation mechanisms in the low mass range. Nystatin - the macrolide of highest molecular weight in this study - expels several TMSOH molecules and a TMS radical. Amphotericin B underwent extensive rearrangements preliminary to eliminating a series of TMSOH molecules. An apparent equilibrium between the keto and ketal forms of amphotericin B facilitated the rearrangements. Pimaricin fragmented in a manner parallel to that of the other two macrolides. The sugar portion of the molecules dominated the fragmentation in the low mass region in the spectra of all compounds. The transfer of a TMS group from the sugar amine to the glycosidic oxygen was observed when the amino sugar was eliminated from the intact molecule. The resulting sugar ion then expelled ammonia.
    Additional Material: 5 Ill.
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  • 3
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method is described for the separation, identification and quantitation of endogenous hydrogenated metabolities of corticosterone in rat liver Corticosterone, 5α- and 5β-dihydrocorticosterone, 3α,11β,21-trihydroxy-5α-pregnane-3,20-dione, 3β,11β,21-trihydroxy-5α-pregnane-3,20-dione, 3α,11β,21-trihydroxy-5β-pregnane-3,20-dione, 3β,11β,21-trihydroxy-5α-pregnane-3,20-dione, 5α-pregnane-3α,11β,20α,21-tetrol, 5α-pregnane-3α,11β,20β,21-tetrol and 5α-pregnane-3β,11β,20β,21-tetrol are specifically quantitated in one analysis by mass fragmentography all as their O-methyloxime pertrimethylsilyl derivatives. A pronounced difference in the amounts of these nine metabolites between male and female adult rats was found, while in newborn rats only the two tetrahydro-compounds bearing a 5α-hydrogen were detected in both sexes. On the other hand 3α,11β,1 5α,21-tetrahydroxy-5α-pregnan-20-one was detected only in the adult female as its second prominent metabolite of corticosterone. Corticosterone metabolites being biochemical markers of the sex-linked differentiation of the hepatocytes, their mass fragmentographic assay is proposed as a tool for the quantitative analysis of this type of gene expression.
    Additional Material: 8 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 1 (1974), S. 62-65 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The separation and structural determination of ten partially methylated methyl glucosides by gas chromatography and gas chromatography-mass spectrometry are described. These glucosides were four possible structures for methyl tri-O-methylglucosides and six for methyl di-O-methylglucosides. The positions of free hydroxyl groups in four isomers of methyl tri-O-methylglucosides could be fairly distinguished from each other by their mass spectra. Mass spectra of methyl di-O-methylglucosides were similar to each other, though their spectra were different from those of fully methylated or methyl tri-O-methylglucosides. After introduction of a trimethylsilyl group to the free hydroxyl group, mass spectra of methyl di-O-methylglucosides showed a characteristic pattern for the position of the trimethylsilylated hydroxyl group, and O-trimethylsilyl ethers of methyl tri-O-methylglucosides also showed distinguishable mass spectra. The structures of fragment ions of partially methylated methyl glucosides were confirmed by high resolution mass spectrometry.
    Additional Material: 4 Tab.
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  • 5
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 1 (1974), S. 80-82 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Monitoring of solutes eluted from a liquid chromatograph is possible by continuous introduction of the effluent solution into the ion source of a chemical ionization mass spectrometer. Detection sensitivities in the nanogram range are possible for a wide variety of solutes and solvents. Auxiliary techniques which have proved valuable for g.c.-m.s. also appear to be applicable to l.c.m.s.
    Additional Material: 3 Ill.
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  • 6
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The determination of drug metabolites is very important in the biochemical field. However, the procedure for doing this has been very complicated in many cases. The major reason is because of the need for fairly large amounts of the samples. We have been studying procedures for the determination and identification by use of mass spectrometry, which usually gives a lot of information rapidly from very small amounts of the samples (below μg). In this paper, the metabolites excreted in urine and bile following oral administration of 2-(diethyamino)ethyl tetrahydro-α-(1-naphthylmethyl)-2-furanpropionate oxalate (1) in rats, were investigated by means of mass spectrometry and other techniques. The drug was not excreted unchanged in urine. Of the eight metabolites suspected to be present in urine and bile, the structures of three metabolites were elucidated to be tetrahydro-α-(1-naphthylmethyl)-2-furanpropionic acid (3) and α-(1-naphthylmethyl)-2-perhydro-5-oxofuranpropionic acid (4) in urine, and diethylaminoethanol (2) in bile. These metabolites might also be present as their structural isomers or conjugates.
    Additional Material: 11 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 1 (1974) 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 8
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 1 (1974), S. xiv 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 9
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 1 (1974), S. 83-95 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The use of the integrated ion current technique for the analysis of biogenic amines and phenols as their 1-dimethylaminonaphthalene-5-sulphonyl (dansyl) derivatives is described, particularly as regards to the linearity and sensitivity of detection. The mono derivatized amines gave a linear response over the range 10-9 to 10-14 mol, with a few being detected in quantities as small as 5 × 10-15 mol. The bisdansyl derivatives have a lower sensitivity and the response is linear over a more restricted range, terminating at 10-13 mol. Deuterated analogues of some of the amines were prepared and the feasibility of their use as internal standards was investigated. In this way, the problems associated with quantitative biochemical analyses caused by losses during extractions, chromatographic separations and thermal decomposition in the mass spectrometer lon source are overcome. The differentiation of isomers of biogenic amines as their dansyl derivatives has been accomplished by fractional sublimation and by examination of differences in their fragmentation patterns.
    Additional Material: 7 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 1 (1974), S. 115-119 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The amino acids, arginine, citrulline, cysteine, cystine, histidine, hydroxyproline, methionine, ornithine, proline, serine, threonine, tryptophan and tyrosine, have been analysed in the form of their N-(N′, N′-dimethylaminomethylene) methyl esters. formed in a single step by reaction of the free amino acid or its hydrochloride with N,N-dimethylformamide dimethylacetal in acetonitrile/methanol (2:1). A reaction time of 15 minutes at 100 °C ensures complete derivatization, the derivatives being volatile at source temperatures below 150 °C, and giving electron impact spectra characterized by abundant (or moderately abundant) peaks at or near the mass of the molecular ion.The analysis of amino acid mixtures by mass fragmentography on characteristic high mass peaks of their N-(N′,N′-dimethylaminoethylene) methyl ester derivatives, introduced on a direct insertion probe and volatilized during temperature programming of the source, is qescribed. The method is applied to the analysis of a mixture containing arginine, citrulline, cystine, histidine and tryptophan, traditionally difficult to analyse by other methods.
    Additional Material: 6 Ill.
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