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  • Analytical Chemistry and Spectroscopy  (21)
  • Earth Resources and Remote Sensing  (21)
  • GENERAL  (16)
  • 1
    Electronic Resource
    Electronic Resource
    Determination of the photodegradation products of basic yellow 2 by thermospray high-performance liquid chromatography and gas chromatography/mass spectrometry (1989)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 1079-1086 
    Details
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Like most dyes, Basic Yellow 2 (BY-2) fades upon prolonged exposure to light. Light-induced fading is a complex process that is also affected by heat and humidity. In order to better understand the photodegradation process and to identify the various photodegradation products of BY-2, fabric samples and solutions containing BY-2 were exposed to a variety of fading conditions. The analysis of faded BY-2 dyed fabric extracts by high-performance liquid chromatography/mass spectrometry (HPLC/MS) indicated the reduction and hydrolysis of the C=NH2+ group to form primarily benzophenone derivatives, as well as various demethylated products. Due to the absence of fragmentation in the thermospray spectra (only [M + H]+ ions were observed) the dye extracts were analyzed by gas chromatography/mass spectrometry (GC/MS) to confirm the identity of the degradation products. Many of the degradation products were sufficiently volatile for analysis by GC/MS. Mass spectra of the photodegradation products of BY-2 exhibited molecular ions and structurally important fragment ions to complement the thermospray data. The mass spectral data indicated that the most prevalent degradation product formed was ((CH3)2NC6H4)2C=0 (Michler's ketone). Hydrolysis of the C=NH2+ group to C=0 is the main color-destroying reaction in the fading of BY-2. Demethylation products which can alter the shades of color were also detected in the faded BY-2 samples.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200181208
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  • 2
    Electronic Resource
    Electronic Resource
    The application of flow switching rotary valves in two-dimensional high resolution gas chromatography (1979)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 55-62 
    Details
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two-dimensional high resolution gas chromatography with small bore glass capillary columns is simplified by use of a single 6-port flow switching rotary valve. The band spreading and tailing normally associated with mechanical valves is overcome by matching the internal valve passage diameters to that of the capillary column, and by minimizing unswept volumes in the fittings. selection of inert valve and transfer line materials effectively ellminates undesirable adsorption phenomena. The high thermal stability of the value permmits it to be mounted directly in the GC oven where it can be actuated externally. With slight modifications either packed or capillary pre-columns may be used for initial saperations. Application of enrichment, solvent removal and heart cutting are described.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240020202
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  • 3
    Electronic Resource
    Electronic Resource
    Applications of heart cutting from packed to capillary columns (1982)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 5 (1982), S. 546-552 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Multidimensional ; Deans switching ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The power of capillary gas chromatography can be enhanced by selective fractionation of the sample. One way of doing this is heart cutting from a packed gas chromatographic column. This paper describes modification of a commercial instrument for such separations. Components of the system include an automated Deans switch and an electrically heated trap. The benefits of this arrangement are illustrated with chromatograms of naphtha, urinary aromatic acids, and wine volatiles.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240051006
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  • 4
    Electronic Resource
    Electronic Resource
    Optimizing gas chromatographic separations (1987)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 10 (1987), S. 231-234 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary columns ; Selectivity tuning ; Optimization ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: While separations based on the use of stationary phases specifically designed to maximize solute alphas can, in the strictest sense, be precisely optimized only under specific isothermal conditions, the approach has previously been used even with temperature programmed separations. Selectivity can by further “tuned” by (1) differential variations in the carrier gas velocity through dissimilarly coated coupled columns, and (2) temperature variations in columns of at least moderate polarity. This paper explores the latter approach.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240100504
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  • 5
    Electronic Resource
    Electronic Resource
    A new bonded stationary phase for the gas chromatographic separation of volatile priority pollutants and chlorinated pesticides (1985)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 8 (1985), S. 715-717 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary column, fused silica ; Immobilization ; Polymethylsiloxane stationary phase ; Priority pollutants ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new phenyl-cyanopropyl polymethylsiloxane stationary phase, DB-1301, which can be crosslinked and bonded to the fused silica surface, has been synthesized. The phase composition was optimized for the separation of 18 volatile priority pollutants, selected from the so-called “purgables” list because of problems associated with their resolution. The composition of the stationary phase was based on theoretical considerations of binary phase mixtures and window diagram prediction. Columns coated with this stationary phase are compatible with atom selective detectors, such as the electron capture detector. A mixture of 18 volatile priority pollutants and a mixture of chlorinated pesticides were used as test probes on a prototype 30 m × 0.32 mm fused silica column, containing a 1.0 μm film of DB-1301.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240081105
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  • 6
    Electronic Resource
    Electronic Resource
    Analysis of three aminonitropyrene isomers via fused silica gas chromatography combined with negative ion atmospheric pressure ionization mass spectrometry (1987)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 10 (1987), S. 43-45 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Mass spectrometry ; Capillary GC ; Fused silica GC ; Nitro-PAHs ; Aminonitropyrene ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240100110
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  • 7
    Electronic Resource
    Electronic Resource
    AC corona-discharge aerosol-neutralization device adapted to liquid chromatography/particle beam/mass spectrometry (1995)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 9 (1995), S. 138-142 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: An AC corona-discharge device was inserted upstream of a thermospray vaporizer tip in a liquid chromatography/particle beam mass spectrometer to neutralize static aerosol charging. Response of a test analyte was measured with or without discharge initiation. If the solvent contained no ammonium acetate buffer, increased analyte signal was associated with the discharge. However, in the presence of ammonium acetate the benefit of AC discharge neutralization was either not observed or was more subtle. This led to the conclusion that the previously observed ammonium acetate “carrier” effect is attributable, at least in part, to neutralization of static electric charges produced spontaneously during the solvent nebulization process. In a second experiment, the pattern of particles issuing from the system momentum separator was examined by aiming the particle beam at a cold target located within a mass spectrometer ion source. Variations in particle density were observed depending on (i) whether or not the aerosol had been neutralized and (ii) the proximity of electron-beam-collimating magnets to the particle beam trajectory. These results are consistent with a hypothesis that electrostatic charging occurs spontaneously during the nebulization process in which an aerosol is formed from the high performance liquid chromatography effluent. Such electrostatic charging introduces a factor likely to degrade system performance by at least two modes: through interactions of the charged aerosol particles (i) with the walls of the aerosol transmission pathway, and, after they are accelerated into a particle beam and introduced into the mass spectrometer, (ii) with the magnets used for electron beam collimation in many mass spectrometer ion sources.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290090207
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  • 8
    Electronic Resource
    Electronic Resource
    Analysis of rat urine for metabolites of pyrilamine via high-performance liquid chromatography/thermospray mass spectrometry and tandem mass spectrometry (1990)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 19 (1990), S. 191-201 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Combined high-performance liquid chromatography/thermospray mass spectrometry (HPLC/TSMS) and HPLC/thermospray tandem mass spectrometry (HPLC/TSMS/MS) were utilized for the analysis of rat urine for metabolites of pyrilamine. The sample was analyzed via HPLC/TSMS/MS in the parent ion mode in order to identify potential metabolites of pyrilamine. Then HPLC/TSMS/MS analysis in the daughter ion mode was performed to provide additional analytical selectivity plus enhanced fragmentation of suspected protonated molecules. By this methodology, suspected pyrilamine metabolites were confirmed to be in the sample and several novel metabolites of pyrilamine were discovered and tentatively identified.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200190317
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  • 9
    Electronic Resource
    Electronic Resource
    1H NMR and 13C NMR spectra of disulfides, thiosulfinates and thiosulfonates (1981)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 17 (1981), S. 53-58 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 1H NMR and 13C NMR spectra of neopentyl and benzyl substituted disulfides, thiosulfinates, thiosulfonates, thiols, sulfides, sulfinic acids and sulfonic acids are reported. The deshielding electron withdrawing effects of -SO, -SO2, -SO2-, -SO2H, -SO3-, -SO3H and SO3CH3 on α-methylene and benzylic protons are observed. The 1H NMR spectra show, except for two dialkylthiosulfinates, that the α'-protons of thiosulfinates absorb farther downfield than those of the thiosulfonates. Although the 13C NMR spectra show that αSO effects are deshielding and are smaller than the αSO2 effects, the α'SO values are more shielding than the α'SO2 values for some compounds. The effects on 13C NMR spectra which result from substituting a phenyl group for a neopentyl or benzyl group are discussed. The α-methylene carbon shifts for neopentanesulfinic acid and α-toluenesulfinic acid are further downfield than those for the corresponding sulfonic acids.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270170113
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  • 10
    Electronic Resource
    Electronic Resource
    Chemical ionization mass spectrometry of doxylamine and related compounds (1985)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 20 (1985), S. 435-439 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The chemical ionization mass spectrometric (CIMS) analysis of doxylamine, N,N-dimethyl-2-[1-phenyl-1-(2-pyridinyl)ethoxy]ethanamine, and related compounds, using both ammonia and methane as reagent gases, is discussed. The two reagent gases did not produce the same major fragment ion for doxylamine. Mechanisms for the fragmentation of doxylamine under either ammonia or methane CIMS conditions are proposed. The mechanisms explain the observation of an m/z 182 fragment ion for doxylamine analyzed under methane CIMS conditions and an m/z 184 product ion detected under ammonia CIMS conditions.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210200702
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