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  • Analytical Chemistry and Spectroscopy  (21)
  • Humans  (9)
  • 1
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The collision-induced dissociation of positively charged gold clusters (2-23 atoms) stored in a Penning trap has been studied. After collisions with rare gases, excited clusters predominantly decay by emission of one or two atoms. The loss of two atoms occurs most probably through the emission of a dimer rather than by a sequential evaporation. The minimum kinetic energies of clusters required to induce dissociation exhibit a pronounced odd-even effect. Clusters with an even number of delocalized electrons are more stable than those with an odd number.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0935-6304
    Keywords: Ion mobility spectrometry (IMS) ; Ion mobility detection (IMD) ; Capillary GC ; Capillary SFC ; Liquid Chromatography ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ion mobility monitoring has been used for detection in gas, supercritical fluid, and liquid chromatography, illustrating its potential as a method of detection for unified chromatography. Applications presented include GC-IMD of dioxins in fly ash, SFC-IMD of vitamin E, and HPLC-IMD of alkylamines.Ion mobility spectra of several mixed supercritical fluid mobile phases are also presented. Use of methanol, acetonitrile, and dichloromethane as modifiers of supercritical carbon dioxide, and use of supercritical dichlorodifluoromethane and chlorodifluoromethane as mobile phases had little effect on the reactant ion pattern at the flow rates and concentrations used in this study. Only when acetone was used as a modifier of carbon dioxide did the positive reactant ions change significantly. No effect of modifiers or mobile phase was observed for the negative reactant ions.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Matrix-assisted laser desorption/ionization mass spectrometry was used for the characterization of extracted and synthesized oligo(ethylene terephthalate)s. Generally, cyclic oligomers [GT]n could be found in technical yarns and tiles, whereas our synthesized model oligomers mainly consisted of linear chains H—[GT]n—G. In addition, some other distributions could be identified as H—[GT]n—OH and H—[GGT]1—[GT]n-1—G linear oligomers and H—[GGT]1—[GT]n-1 cyclic oligomers, where G is an ethylene glycol unit, GG is a diethylene glycol unit, caused by impurities of ethylene glycol, and T is a terephthalic acid unit. NMR and IR investigations were carried out to verify these results.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 29 (1991), S. 1114-1118 
    ISSN: 0749-1581
    Keywords: 1-Pyrroline 1-oxides ; 2H-Pyrroles ; 1-Pyrrolines ; Oxaziridines ; 13C NMR ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 13C NMR data for forty 1-pyrroline 1-oxides, six 2H-pyrrole 1-oxides, three 2H-pyrroles, eight 1-pyrrolines and four related oxaziridines are reported. Comparisons are made with respect to the five-membered ring carbons, subdividing them as the central carbons, the nitrone carbon and the gem-dimethyl-substituted carbon adjacent to nitrogen. The effects of substituents on the ring are also discussed.
    Additional Material: 8 Tab.
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  • 5
    ISSN: 0749-1581
    Keywords: 13C NMR ; 2(5H)-Furanones ; 3(2H)-Furanones ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 13C NMR spectra of a series of novel 2(5H)-furanones were studied. The assignments of the carbon resonances were made on the basis of chemical shifts, long-range carbon-hydrogen couplings, intarnal comparison and known reference sources.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biospectroscopy 3 (1997), S. 409-416 
    ISSN: 1075-4261
    Keywords: pigment gallstones ; thalassemia ; FTIR ; FT-Raman ; Mössbauer spectroscopy ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: The chemical composition of a suite of pigment gallstones obtained from patients suffering from β-thalassemia was studied using FTIR, FT-Raman, and Mössbauer spectroscopies with a view to gaining a better understanding of their complex composition and developing an effective characterization procedure. The combination of vibrational spectroscopic techniques such as FTIR and FT-Raman make it possible to identify the major chemical components of thalassemic pigment stones and to subcategorize them for further study. All but one sample had almost identical FTIR spectra where bands attributable to both cholesterol and various bilirubinate salts were observed. One sample, low in cholesterol, showed distinctive spectral peaks of calcitic CaCO3. This sample was sufficiently high in iron for Mössbauer spectroscopy, which showed, at room temperature, a quadrupole-split doublet consistent with the presence of iron (III). This concomitant presence of iron and a high CaCO3/low cholesterol content has, as far as we are aware, not been previously reported. When studied by FT-Raman, however, most of the stones gave spectra typical of previously characterized brown stones. Due to the limited number of stones available, in particular iron-rich samples, further work is required, but these preliminary results indicate that it may in fact be possible to unequivocally categorize thalassemic stones into different types using spectroscopic techniques. Together with FTIR and Raman microscopy of cut stones, such nondestructive spectroscopic techniques show promise in helping researchers gain an understanding of thalassemic stone formation and occurrence. In addition, the samples are maintained for further study, which is important considering the difficulty in establishing large suites of such special category stones. © 1997 John Wiley & Sons, Inc. Biospectroscopy 3: 409-416, 1997
    Additional Material: 5 Ill.
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  • 7
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Liquid chromatography (LC) combined with atmospheric pressure chemical ionization mass spectrometry was used to identify phase I and II metabolites of the drug BW 1370U87 in dog and human urine. Additional analysis of individual high-performance liquid chromatograph fractions collected from dog urine by combined gas chromatography/mass spectrometry identified one metabolite which was not detected by LC/MS methods. Using negative-ion LC/MS, the majority of BW 1370U87 metabolites in human urine were identified as glucuronic acid conjugates of phase I oxidative metabolites. The negative-ion fragmentation produced by low-energy collisionally activated decomposition (CAD), studied by tandem mass spectrometry experiments, confirmed that these compounds were drug-related and allowed metabolite structures to be assigned. Product-ion spectra of the metabolites were dominated by the loss of neutral molecules from even-electron deprotonated [M - H]- ions.
    Additional Material: 9 Ill.
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  • 8
    ISSN: 1040-7685
    Keywords: ion mobility detection ; capillary gas chromatography ; detection limits ; tributylamine ; phenyl sulfide ; tributyl phosphate ; flame ionization detector ; flame photometric detector ; thermionization detector ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method for setting gating parameters is presented that maximizes response in ion mobility detection following capillary gas chromatography. The method requires knowledge of the drift times of the product ion or ions of interest and the drift times of the reactant ions. These values are obtainable from ion mobility spectra captured after capillary gas chromatography.The capillary insertion distance into the ion source and the presence or absence of an aperture grid were also found to have considerable effect on chromatographic response. Under optimized conditions, minimum detectable limits of 〈1 fmol/s are reported for tributylamine, phenyl sulfide, and tributyl phosphate. These values demonstrate significant improvements over reported detection limits of organics by the flame ionization detector and sulfur-containing species by the flame photometric detector. The values show slight improvement over those reported for detection of nitrogen and are comparable to those reported for detection of phosphorus-containing species by the thermionization detector.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1040-7685
    Keywords: open tubular liquid chromatography ; column preparation ; capillary column ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The preparation of open tubular liquid chromatographic columns with small inner diameters (≤ 20 μm) from Pyrex 7740 borosilicate glass is described. The surface area of the inner wall of the capillary is increased by etching with a series of acidic and basic solutions. Dimethyloctadecylchlorosilane is then reacted with the column wall to create a bonded stationary phase layer. The resulting columns exhibit good retention and high efficiency. The effects of each step in the etching process are examined and the silanization reaction is optimized.
    Additional Material: 5 Ill.
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  • 10
    ISSN: 1040-7685
    Keywords: microdialysis ; microcolumn LC ; bis(5-amidino-2-benzimidazolyl)methane ; arthritis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Microcolumn liquid chromatography and microdialysis were coupled together to study the distribution of an IV administered drug into the knee joint of a rat with acute arthritis. Dialysate from microdialysis probes located directly within the intraarticular region and in the surrounding muscle was delivered at a flow rate of 0.25 μL min-1 directly into a microcolumn LC system. A 0.5-mm i.d. microcolumn and fluorescence detector were utilized. An in vitro model was developed to estimate the drug concentration in the dialysate. Differences in drug distribution between the intra and extraarticular knee regions were detected, and the potential utility of this technique in the pharmacokinetic evaluation of site-specific drugs was demonstrated.
    Additional Material: 10 Ill.
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