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  • Analytical Chemistry and Spectroscopy  (21)
  • Earth Resources and Remote Sensing  (21)
  • 1
    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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  • 2
    Electronic Resource
    Electronic Resource
    Hydroxypolychlorodibenzofurans in technical pentachlorophenol: Electron capture negative ion chemical ionization mass spectra of alkoxypolychlorodibenzofurans (1982)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 9 (1982), S. 85-90 
    Details
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A mixture of hydroxypolychlorodibenzofurans was isolated from technical pentachlorophenol. The alkyl ethers were prepared, and analyzed by fused silica capillary column gas chromatography electron capture negative ion chemical ionization mass spectrometry. The appearance of intense molecular ion peaks for the alkyl ethers apparently depends on the ring position of alkoxy substitution. Loss of chlorine atoms from the ring, followed by protonation of the resultant anion as the alkyl group is eliminated, is postulated on the basis of deuterium labeling experlments. Evidence is also presented for the presence of a hydroxyheptachlorodibenzodioxin in technical pentáchlorophenol.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200090209
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  • 3
    Electronic Resource
    Electronic Resource
    13C NMR chemical shifts of thiols, sulfinic acids, sulfinyl chlorides, sulfonic acids and sulfonic anhydrides (1983)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 21 (1983), S. 86-93 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 13C NMR spectra of thiols, sulfinic acids, sulfinyl chlorides, sulfonic acids and sulfonic anhydrides have been obtained. The data are discussed in terms of the additivity of the deshielding effects exerted by the sulfur functionality at the α- or β-position, and the shielding effects produced by the sulfur function at the γ-position.
    Additional Material: 9 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/omr.1270210204
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  • 4
    Electronic Resource
    Electronic Resource
    Chemical ionization and electron impact mass spectra of thiosulfinates, thiosulfonates and sulfinyl sulfonesSee Ref. 1. (1982)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 17 (1982), S. 114-122 
    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 and electron impact mass spectra of some thiosulfinates, thiosulfonates and sulfinyl sulfones have been studied. The electron impact mass spectra of four of the six thiosulfonates show molecular ions of less than 1%. Inconclusive evidence was obtained for sulfenyl sulfinate type intermediates in the electron impact spectra of thiosulfonates. The electron impact spectra of thiosulfonates were similar to those of thiosulfonates. The chemical ionization (isobutane) mass spectra of thiosulfinates and thiosulfonates generally show protonated molecular ions [MH]+ as base peaks and [MH+1]+ and [MH+2]+ peaks.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210170303
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  • 5
    Electronic Resource
    Electronic Resource
    Unique thermospray mass spectrometry of 1,4-benzoquinone and analogs in ammonium acetate solutions (1991)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 26 (1991), S. 697-702 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In general, ions corresponding to [M + H]+ and/or [M + NH4]+ are observed in thermospray mass spectrometry (TSMS) when using ammonium acetate in the liquid carrier. For several quinones investigated, unique thermospray mass spectra were detected with a mass spectral peak corresponding to an [M + 16]+ ion being observed in aqueous ammonium acetate solutions. Investigation of l,4-benzoquinone (BQU) and structurally analogous quinones indicated that amine conjugate formation with BQU and similar quinones was the origin of the unique [M + 16]+ ion in TSMS. When methanol was added to the liquid carrier, ions corresponding to methoxy conjugation were detected. High-performance liquid chromatography followed by TSMS or electrochemical detection gave evidence that this amine and methoxy conjugate formation was occurring in the thermospray source area.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210260806
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  • 6
    Electronic Resource
    Electronic Resource
    Chemical ionization and electron impact mass spectra of S-1-chloroalkyl alkanesulfonothioates (thiosulfonates) (1992)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 27 (1992), S. 611-614 
    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 (CI) and electron impact (El) mass spectra of six S-1-chloroalkyl alkanesulfonothioates (thiosulfonates) are reported.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210270513
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  • 7
    Electronic Resource
    Electronic Resource
    Chemical ionization and electron impact mass spectra of symmetrical S-alkyl alkanesulfonothioates (thiosulfonates) (1992)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 27 (1992), S. 609-610 
    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 (CI) and electron impact (EI) mass spectra of eight symmetrical S-alkyl alkanesulfonothioates (thiosulfonates) are reported.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210270512
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  • 8
    Electronic Resource
    Electronic Resource
    Nuclear magnetic resonance studies: VII - 13C and 15N n.m.r. of diazo compounds (1977)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 9 (1977), S. 75-79 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 13C and 15N n.m.r. results for a series of diazo compounds are reported. It is found that the diazo carbon is shielded by an extraordinary amount compared with normal sp2 hybridized carbons. The 15N chemical shifts reveal that the terminal nitrogen is deshielded relative to the central one. This is contrary to that expected from charge effects but support is found for this phenomenon in other systems. One-bond 13C—14N coupling in diazomethane is also reported for the first time. INDO MO calculations of the charges and finite perturbation calculations of 13C—14N and C—H couplings are compared with the experimental results.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270090206
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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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