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  • Analytical Chemistry and Spectroscopy  (24)
  • 1995-1999  (24)
  • 1
    Electronic Resource
    Electronic Resource
    A spectroscopic investigation of the formation mechanism of pigment gallstones (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Biospectroscopy 3 (1997), S. 381-391 
    Details
    ISSN: 1075-4261
    Keywords: black pigment gallstone ; FTIR ; EPR ; nonlinear phenomena ; vibrational mode ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Further spectroscopic studies of gallstones are reviewed with an emphasis on the formation of black pigment gallstones. This type of gallstone appears mainly in Western countries, with only 3% of the cholelithiasis patients in China having black gallstones. Fourier transform infrared absorption and electron paramagnetic resonance are used as spectroscopic probes of gallstones and their metal bilirubinate components. Nonlinear phenomena in gallstone formation were investigated through the appearance of ring structure in gallstones and fractal patterns in the formation in the precipitates of bile salt systems. Although a complete understanding of gallstone formation has not yet been achieved, interesting progress toward this goal has been made recently. © 1997 John Wiley & Sons, Inc. Biospectroscopy 3: 381-391, 1997
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    A spectroscopic study of pigment gallstones in China (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Biospectroscopy 3 (1997), S. 371-380 
    Details
    ISSN: 1075-4261
    Keywords: brown pigment stone ; PAGE ; mid-IR spectroscopy ; far IR spectroscopy ; FT-Raman ; bezoar ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Spectroscopic studies of various types of gallstones carried out in China are reviewed. Three basic classes of gallstones are surveyed: cholesterol stones, brown pigment stones, and black pigment stones. The emphasis of this review is on brown gallstones. The primary spectroscopic methods used in the studies surveyed are Fourier transform infrared absorption and Fourier transform Raman scattering. Chemical components studied in gallstones include cholesterol, bile pigments, glycoproteins, proteins, bilirubin metal complexes, and salts of calcium and other metals. Further studies are needed characterize the relationship of these components to more complex features of gallstones. © 1997 John Wiley & Sons, Inc. Biospectroscopy 3: 371-380, 1997
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Deconvolution algorithms for instrumental applications: A comparative study (1995)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 9 (1995), S. 3-20 
    Details
    ISSN: 0886-9383
    Keywords: Deconvolution algorithms ; Instrumental analysis ; Spectrometry ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Deconvolution algorithms for measurand reconstruction are considered. Their metrological and numerical properties are briefly characterized. Six algorithms most frequently used for instrumental applications are selected for closer analysis. Their comparative study is based on the use of spectrometric-type synthetic data, calorimetric-type synthetic data and spectrometric real-world data. Conclusions concerning computational complexity and accuracy of the compared algorithms as well as their metrological applicability are drawn.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180090103
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  • 4
    Electronic Resource
    Electronic Resource
    Electron-impact induced decomposition of some 3-alkyl-5-substituted-6-methyl uracils (1995)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 9 (1995), S. 854-855 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Mass spectrometry was used to study the main fragmentation routes of some 3-alkyl-5-substituted-6-methyl uracils. Differences in fragmentation were caused by changes in the structure of the alkyl group in position 3 of the uracil ring, with the same substituent in position 5, and by differences in the substituent in position 5.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290090927
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  • 5
    Electronic Resource
    Electronic Resource
    Membrane extraction combined with a sorbent coated fiber interface for capillary gas chromatography (1995)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 18 (1995), S. 727-732 
    Details
    ISSN: 0935-6304
    Keywords: Fiber ; Membrane ; Headspace analysis ; Environmental analysis ; Fast gas chromatograph ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240181113
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  • 6
    Electronic Resource
    Electronic Resource
    Correlation between structure of dihydropyridine calcium antagonists and their retention behavior and enantioseparation on the β-cyclodextrin stationary phase in HPLC (1995)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 18 (1995), S. 597-601 
    Details
    ISSN: 0935-6304
    Keywords: HPLC ; Chiral separation ; β-Cyclodextrin ; Molecular modeling ; Calcium antagonists ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chromatographic data for five dihydropyridine calcium antagonists (CAs) were obtained on β-cyclodextrin column in the reversed phase HPLC. Interaction energies of solute-cyclodextrin complexes formed by docking of different parts of the CAs' molecules into the cyclodextrin cavity were calculated. Results from the HPLC experiments and molecular modeling were compared. It was found that several types of inclusion complexes are energetically possible and contribute to the retention simultaneously. Only certain inclusion complex are assumed to be responsible for enantioseparation of CAs. Nevertheless molecular modeling studies are a useful tool for explaining the enantioselectivity and predicting the elution order of enantiomers.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240180917
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  • 7
    Electronic Resource
    Electronic Resource
    Normal and inverse electron demand Diels-Alder cycloaddition of protonated and methylated carbonyl compounds in the gas phase (1995)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 30 (1995), S. 581-594 
    Details
    ISSN: 1076-5174
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Protonated and methylated quinones, α,β-unsaturated ketones and aldehydes and saturated ketones all react to form cycloaddition products with butadiene. The reagent ions are generated by chemical ionization (CI) and react at nominally zero kinetic energy with butadiene in an r.f.-only quadrupole of a pentaquadrupole mass spectrometer. In selected cases, the product ions were characterized by sequential product ion dissociation (triple stage mass spectrometry [MS3]). The activated dicarbonyl ions, such as protonated quinone and protonated 4-cyclopentene-1,3-dione, are more reactive than the protonated α,β-unsaturated carbonyl compounds and the protonated saturated ketones. The methylated ions are less reactive than their protonated analogs. MS3 spectra of the quinone and α,β-unsaturated carbonyl adducts and ab initio calculations of product ion stability are interpreted as indicating Diels-Alder cycloaddition at the carbon-carbon double bond. Benzoquinones and the α,β-unsaturated ketones are also good dienophiles in solution. The differences in reactivity between these two groups of reactant ions, between the protonated and methylated ions and between individual members of each of these groups are ascribed to differences between the HOMO and LUMO orbital energies (ΔE) of the diene and reactant ion, respectively. The correlations observed between the cycloaddition reactivity and the energy gap indicate that normal Diels-Alder reactions occur for the quinones and α,β-unsaturated ions. Correlations between ion-molecule reactivity and the HOMO-LUMO energy gaps also extend to the protonated saturated ketones, where MS3 studies confirm that cycloaddition occurs at the carbon-oxygen double bond. In all cases, when the proton affinity of the conjugate base of the dienophile is close to that of the diene, proton transfer between the diene and the dienophile becomes a major competitive process; this in turn decreases the cycloaddition yield. Gas-phase inverse electron demand Diels-Alder reactions are studied using methylated 2-butenone as diene and several neutral alkenes as dienophile. Higher reactivity is achieved with electron-donating alkenes as dienophiles, in agreement with observations made in solution chemistry on inverse electron demand Diels-Alder reactions.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jms.1190300409
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  • 8
    Electronic Resource
    Electronic Resource
    Ion-molecule reactions of C60Rh+ with CH3X, C6H5X(X = Cl, Br, I) and CH2I2 (1995)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 30 (1995), S. 834-840 
    Details
    ISSN: 1076-5174
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The gas-phase ion-molecule chemistry of exohedrally bound C60Rh+ with CH3X, C6H5X (X = Cl, Br, and I) and CH2I2 is studied using Fourier transform ion cyclotron resonance mass spectrometry. Reactions with CH3I and CH2I2 yield the buckminsterfullerene derivatives, C60CH3+ and C60CH2+, respectively. Energy resolved collisional activation experiments on these two product ions indicate that the methylene group is more strongly bound to C60 than the methyl group. This is consistent with methylene being bound by two carbon-carbon bonds to C60, while methyl is bound by a single carbon-carbon bond. Unlike CH3I, CH3Cl and CH3Br react with C60Rh+ in a stepwise fashion to yield C60Rh(CH2)n+ (n = 1 - 3). Interestingly, C60Rh(CH2)2,3+ are shown to be isomers of C60RhX+ (X = ethene, propene), possibly with a carbon-carbon bond formed with C60. Products containing more than three CH2 moieties were not observed. Reactions of C60Rh+ with C6H5X(X = Cl, Br, and I) yield C60Rh(C6H4)n+ (n = 1, 2), in a stepwise fashion via losses of HX. C60Rh(C6H4)2+ is unreactive with C6H5X. Again, indirect evidence for C—C bond formation to C60 is obtained. Consistent with previous observations on C60Fe+ C60Co+, the Rh+-C60 bond energy is found to fall between those of Rh+-propene and Rh+-benzene, due to the alkene behavior of C60.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jms.1190300608
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  • 9
    Electronic Resource
    Electronic Resource
    Massive cluster impact ionization on a four sector tandem mass spectrometer (1995)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 30 (1995), S. 140-143 
    Details
    ISSN: 1076-5174
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: High energy gycerol cluster ions from an electrohydrodynamic ion gun have been used as a primary ion beam to generate secondary ions of proteins with molecular weights up to 29 kDa and oligonucleotides. The technique not only demonstrated good performance in the picomole/nanomole range for the desorbtion of highly polar and fragile molecules such as proteins and deoxyoligonucleotides, but it also allowed the observation of a non-covalent complex in the form of a deoxyoligonucleotide duplex. We have also shown that it is feasible to carry out structural analysis of oligonucleotides by collisional activation in a four sector tandem instrument.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jms.1190300121
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  • 10
    Electronic Resource
    Electronic Resource
    Formation of buckministerfullerene phenylene derivatives in the gas phase (1995)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 30 (1995), S. 194-200 
    Details
    ISSN: 1076-5174
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The gas-phase chemistry of Fe(C6H4)n+ (n = 1-6) with C60 is studied by using Fourier transform ion cyclotron resonance mass spectrometry. The formation of some ionic phenylene derivatives and metallacyclic derivatives of C60 is observed. Specifically, Fe+, generated by laser desorption, reacts with chlorobenzene to form iron-benzyne, FeC6H4+, which initiates further reactions with chlorobenzene to form Fe(C6H4)2-6+ and (C6H4)2-5+. Fe(C6H4)1-4+ react with C60 to form metalated fullerene derivatives, C60Fe(C6H4)1-4+. C60Fe(C6H4)1, 2+ undergo a demetalation reaction with chlorobenzene to yield the fullerene phenylene derivatives C60(C6H4)1, 2+, 8 and 9, through formation of C—C bonds with C60. CID experiments and kinetic analysis indicate that each of the C60Fe(C6H4)1, 2+ species consists of a single isomer, presumably the metallacycles 12 and 14. Consistent with the typical reactions of metal-benzyne complexes with alkenes in the condensed phase, these metallacyclic structures are believed to be formed through coupling of one of the double bonds at the 6,6 ring junction in C60 with an Fe—C σ bond of Fe(benzyne)+. These results are consistent with the notion that C60 acts like an electron deficient alkene rather than an aromatic molecule, and suggest a possible synthetic route to prepare this type of metallo-C60 derivatives in the condensed phase. Finally, ligand displacement reactions yield a bond dissociation energy of D°(Fe+—C60) = 44 ± 7 kcal/mol.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jms.1190300129
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