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  • Analytical Chemistry and Spectroscopy  (657)
  • 1985-1989  (657)
  • 1960-1964
  • 1935-1939
  • 1
    Electronic Resource
    Electronic Resource
    Determination of chlorpromazine and its major metabolites by gas chromatography/mass spectrometry: Application to biological fluids (1985)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 12 (1985), S. 707-713 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method for the quantitative determination of chlorpromazine and five of its major metabolites in a single sample of biological fluid in the ng/ml range has been developed utilizing gas chromatography/mass spectrometry with selected ion recording. The assay is highly specific and quantification is accomplished by an inverse stable isotope dilution technique, using deuterium-labeled variants of the compounds as internal standards. In this way the concentrations of chlorpromazine and five of its major metabolites (the sulfoxide, the N-oxide, the monodemethylated, the didemethylated, and the 7-hydroxylated compounds) can be determined in biological fluids. Levels in humans have been measured both in plasma and in red blood cells and are compared to those found in related in vitro studies.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200121207
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  • 2
    Electronic Resource
    Electronic Resource
    Separation, detection, and identification of inositol triphosphate and phytic acid derivatives by supercritical fluid chromatography and SFC-mass spectrometry (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Microcolumn Separations 1 (1989), S. 182-189 
    Details
    ISSN: 1040-7685
    Keywords: supercrirical fluid chromatography ; mass spectrometry ; capillary column ; inositol ; phosphate ; phytic acid ; silyl derivatives ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Capillary supercritical fluid chromatography with flame ionization detection appears promising for the separation and detection of silylated inositol phosphates. Inositol triphosphate and phytic acid, following ion exchange to their fully protonated forms, were silylated in one step with the addition of 9 and 12 trimethylsilyl groups, respectively. The resulting derivatives are well behaved in open-tubular chromatography columns with methyl-silicone stationary phase when CO2 is used as the mobile phase. Both flow-splitting and directinjection methods were evaluated. The identities of the derivatives were confirmed by supercritical fluid chromatography-mass spectrometry using chemical ionization with both ammonia and isobutane, and using electron ionization - CO2 charge exchange.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mcs.1220010405
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  • 3
    Electronic Resource
    Electronic Resource
    Quantitative analysis of adenosine: Statistical comparison of radioimmunoassay and gas chromatography - mass spectrometry - selected ion monitoring methods (1986)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 13 (1986), S. 667-675 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new method for quantitating adenosine concentration by capillary gas chromatography-mass spectrometry-selected ion monitoring (GC-MS-SIM) has been developed and used as a reference method for evaluating a newly developed radioimmunoassay (RIA) for adenosine. Details of the GC-MS-SIM method are presented, along with the comparative results and uncertainties of both methods. General considerations in the statistical analysis of method comparison data are discussed with particular reference to studies using quantitative mass spectrometry as the standard method; the adenosine methods are used as specific examples in this discussion. Simultaneous estimation of the y-intercept and slope of the least squares regression line relating the results of the two methods using the 95% joint confidence ellipse demonstrated the absence of either constant or proportional error between the two methods. The relatively small uncertainty in the GC-MS-SIM measurements had no significant effect on the linear regression. Random error between the two methods was detected, and was estimated by the coefficient of variation in the RIA data as ten percent of the RIA value.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200131206
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  • 4
    Electronic Resource
    Electronic Resource
    The measurement of vitamins D2 and D3 and seven major metabolites in a single sample of human plasma using gas chromatography/Mass Spectrometry (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 16 (1988), S. 81-85 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Selected ion monitoring of vitamin D metabolites has previously been described but there has been only one detailed description of the measurement by gas chromatography/mass spectrometry (GC/MS) of a number of metabolites in a single plasma sample. We describe here a GC/MS method, using stable isotope labelled internal standards, which allows the estimation of vitamins D2 and D3, and their 25-hydroxy, 24,25-dihydroxy and 25,26-dihydroxy metabolites in a single 2 ml sample of plasma, although more is needed for the measurement of 1,25-dihydroxyvitamin D3. Plasma was extracted on Bond Elut C18 cartridges and initial fractionation carried out on Sep-Pak SIL. Straight-phase high-performance liquid chromatography was required for separation of polyhydroxylated metabolites prior to GC/MS using an LKB 2091 mass spectrometer with conventional packed columns. n-Butylboronate esters were formed across vicinal hydroxyls, followed by formation of trimethylsilyl ethers using trimethylsilylimidazole. The [M - 90 - 15]+ ion for each compound was monitored. Deuterated internal standards were not available for all metabolites and it was necessary to use (2H6)D3 and (2H6)25OHD3 as standards for the measurement of D2 and D3, and 25OHD3 and 25OHD2, respectively, and (2H6)24,25(OH)2D3 as a standards for 24,25(OH)2D3 and 25,26(OH)2D2. Although the [M - 90 - 15]+ ion of 24,25(OH)2D and 25,26(OH)2D has the same mass: charge ratio, derivatives of these compounds are completely separated in the GC system used. The intra-assay precision for all these assays is usually less than 5%.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200160116
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  • 5
    Electronic Resource
    Electronic Resource
    Determination of metals in oil using total reflection X-ray fluorescence spectrometry (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 16 (1987), S. 161-165 
    Details
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Oil was chosen as a new sampl type for total reflection XRF. A thin-film sample procedure is described which requires minimal sample preparation. This involves first bringing the oil into solution with a volatile solvent, then pipetting microliter amounts on to the reflector substrate followed by evaporation of the solvent. The linear dynamic range was found to extend to at least 5000 ppm. Detection limit measurements show that minute sample quantities are necessary for optimal detection limits of nanogram amounts. A maximum sample loading is required for the best detection limits in ppm. Using an Mo or Cu X-ray tube, limits were found to be a few ppm or sub-nanogram amounts. The spectrometer was calibrated by an internal standardization method and the results of determinations on sample solutions were typically within 10% relative accuracy.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/xrs.1300160405
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  • 6
    Electronic Resource
    Electronic Resource
    13C NMR assignments of the isoprenoid chain carbons of retinoids from empirical chemical shift differences (1987)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 25 (1987), S. 1040-1045 
    Details
    ISSN: 0749-1581
    Keywords: α-retinal ; α-ethyl retinoate ; α-retinol ; α-retinoic acid ; 3,4-dehydroretinal ; 3,4-dehydroretinol ; ethyl 3,4-dehydroretinoate ; 3,4-dehydroretinoic acid ; 2D heteronuclear-correlated spectroscopy ; APT ; empirical chemical shift calculations ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 13C NMR assignments have been made for a series of 36 α- and 3,4-dehydroretinoids with different substituents (alcohol, ester, aldehyde and acid) and for their separated E and Z geometrical isomers. The assignments were made by using 2D heteronuclear-correlated NMR experiments. From the chemical shift data of 24 systematically related retinoids, empirical chemical shift changes due to four polar end groups (alcohol, aldehyde, carboxylic acids and esters), three chain configurations (all-E, 9Z and 13Z), and two ring substitutions (2,6,6-trimethyl-cyclohex-2-enyl and 2,6,6-trimethylcyclohexa-1,3-dienyl) were determined. All trends were found to be independent of each other, except for the dependence of the chemical shift change of the 13Z-isomers on the polar end groups. The chemical shift changes were used to predict the chemical shifts of other retinoids based on two different ring structures (2,6,6-trimethylcyclohexenyl and 4-methoxy-2,3,6-trimethylphenyl).
    Additional Material: 8 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260251204
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  • 7
    Electronic Resource
    Electronic Resource
    Isotope label scrambling in alkyl cations. A mechanistic proposal (1989)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 3 (1989), S. 289-292 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The observation of sharp limits to the chain lengths of alkyl cations derived by low energy collision-induced dissociation of isotopically labelled trimethyltetradecylammonium cations, as well as the selectively limited scrambling of its isotope label, has prompted the proposal of a new mechanistic model for alkyl cation fragmentation. The model invokes protonated cyclopropane intermediates which may reopen to branched structures, or fragment (if suitably substituted) to form smaller alkyl cations and neutral olefins. The model accounts completely for the absence of daughter ions with fewer than three or more than six carbon atoms, while its semi-quantitative application provides a reasonable match to the observed isotope scrambling.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290030904
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  • 8
    Electronic Resource
    Electronic Resource
    Charge separation of triply charged ions (1989)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 3 (1989), S. 186-189 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Formation of multiply charged ions is shown to contribute a significant fraction of the total ionization by high energy electrons, and multiple ionization is almost always followed by charge-separation reactions. Triple ionization and subsequent dissociations can be well characterized by the electron-three ion coincidence technique. Results obtained using this new technique are compared with computer simulations of the dissociations of OCS3+ and SO3+2, and the initial momenta and relátive angles of all three fragments are thereby determined. Triply charged benzene ions are shown to undergo many competing charge-separation reactions.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290030606
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  • 9
    Electronic Resource
    Electronic Resource
    Supercritical fluid chromatography/mass spectrometry with an ion trap detector (1988)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 2 (1988), S. 55-58 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290020305
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  • 10
    Electronic Resource
    Electronic Resource
    Pulsed extraction fieldUS and foreign patents applied for. for neutralization of sample charging in secondary-ion mass spectrometry (1989)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 3 (1989), S. 356-359 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A new technique for inhibiting the build-up of surface charge on electrically non-conducting samples in secondary-ion mass spectrometry (SIMS) when using a negative-ion or neutral primary beam is described. The technique, which involves alternately extracting positive and negative particles from the sample by rapidly reversing the polarity of the secondary-ion extraction voltage, is non-intrusive and applicable to all materials. A static SIMS instrument utilizing a negative-ion and neutral molecular primary beam has been modified to demonstrate the technique.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290031011
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