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  • 1
    Electronic Resource
    Electronic Resource
    Effects of soil fertilization and covering of the culture with plastic film on the provitamin A content of early lettuces (1984)
    Springer
    Plant and soil 80 (1984), S. 139-141 
    Details
    ISSN: 1573-5036
    Keywords: Carotenes ; Covering ; Fertilization ; Lettuce
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Different growing conditions of early lettuces were assayed. Some plots of lettuces were grown covered with a perforated plastic sheet, and other plots were not covered. The soil of some plots was fertilized with a usual N+P+K+S fertilizer used at a normal rate, and the soil of other plots with a fertilizer containing only nitrogen at a rate about 40 times lower than the normal one for N. The total carotenes (provitamin A) contents of the ripe lettuces were measured. Covering with a plastic sheet always decreased the total carotenes contents. The N+P+K+S fertilizer used at normal rate increased, relatively to the nitrogen fertilizer lacking of P+K+S and used at low rate, the total carotenes contents of the non-covered lettuces, but had no or low effect on the total carotenes contents of the covered lettuces.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02232948
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  • 2
    Electronic Resource
    Electronic Resource
    Fragmentation reactions of molecular dications of aromatic heterocyclic fused-ring compounds containing more than one nitrogen atomNRCC 33006. (1992)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 27 (1992), S. 89-96 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fragmentation reactions of both metastable and collisionally activated dications, formed by electron impact ionization of heterocyclic fused-ring aromatic compounds containing more than one nitrogen atom, were investigated. This work is an extension of similar work on analogous compounds containing just one nitrogen atom and on the related polycyclic aromatic hydrocarbons. The results obtained are interpreted in terms of mechanistic proposals concerning the competition between charge-separation and neutral-expulsion reactions, based on variations in diradical character with increasing molecular size and nitrogen content of these molecular dications.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210270204
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  • 3
    Electronic Resource
    Electronic Resource
    Analysis of polycyclic aromatic compounds by supercritical fluid charomatography/mass spectrometry using atmospheric-pressure chemical ionizationNRCC #31956. (1991)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 5 (1991), S. 149-155 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The development of microbore packet-column supercritical fluid chromatography/atmospheric pressure chemical ionization mass spectrometry (SFC/APCI-MS) for the analysis of polycyclic aromatic compounds (PAC) is described. The SFC system was coupled to the mass spectrometer using an improved interface designed to accommodate commercially available fused silica restrictors. The atmospheric pressure chemical ionization characteristics of PAC are discussed and the use of chemical ionization reagents to modify the type of spectra obtained is described. With selected-ion monitoring techniques the interface provided detection limits in the low picogram range for individual PAC standards. Using a photoionization detector for the off-line optimization of chromatographic conditions, SFC/APCI-MS was applied to the analysis of complex mixtures of PAC in coal tar and tar sand oil extracts. Tandem mass spectrometry was used to provide structural information.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290050403
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  • 4
    Electronic Resource
    Electronic Resource
    Use of a moving-belt interface for on-line high-performance liquid chromatography/mass spectrometry characterization of polycyclic aromatic compounds of molecular weight up to 580 Da in environmental samplesNRCC No. 32997. (1991)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 5 (1991), S. 604-610 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The applicability of the moving belt high-performance liquid chromatography/mass spectrometry (HPLC/MS) interface to the analysis of high molecular weight polycyclic aromatic compounds (PACs) in a complex sample derived from coaltar is investigated. This interface provides good preservation of chromatographic integrity and useful electron ioniation spectra of thermally stable PACs of low to moderate volatility up to molecular masses of at least 580 Da. It is concluded that this HPLC/MStechnique will be useful in the analysis of such complex samples, provided a large enoughsuite of standard compounds can be made available.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290051208
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  • 5
    Electronic Resource
    Electronic Resource
    Ortho effects-I: Fragmentation mechanisms in some ortho-substituted nitroarenes (1970)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 3 (1970), S. 993-1007 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectra of o-nitrobenzoic acid, o-nitroanisole, o-nitrosobenzoic acid, o-nitrobenzamide, o-nitrobenzyl alcohol and o-nitrosobenzaldehyde have been studied. Fragmentation mechanisms are proposed for the above compounds; their elucidation was aided by isotopic labeling with D and O18. Two ‘ortho-effects’ are discussed; one involving H atom transfer between substituents and the other migration of an atom or group to a charge carrying vacant ortho position. The importance of nitro to nitrite conversion in molecular and fragment ions is discussed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210030803
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  • 6
    Electronic Resource
    Electronic Resource
    The mass spectra of carboxylic acids - III: The structures of molecular and fragment ions in benzoic acid and related molecules (1970)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 4 (1970), S. 97-107 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectra of benzoic acid and its carboxyl-deuterated derivative have been studied in detail. Molecular and fragment ion structures are proposed and the role of ortho hydrogen atoms in rearrangements is discussed. The behaviour under electron-impact of phthalaldehydic acid and its carboxyl deuterated derivative provides evidence in support of ion structures in the benzoic acid fragmentation. From these results the fragmentation mechanism for phthalic acid is further elucidated. The mass spectrum and fragmentation mechanism of thiobenzoic acid is described and compared with that of benzoic acid.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210040111
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  • 7
    Electronic Resource
    Electronic Resource
    The benzoyl cation: The participation of isolated electronic excited states in the dissociation of molecular ions of the form [C6H5COX]+· (1973)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 7 (1973), S. 1407-1413 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The heat of formation of the benzoyl cation generated from [C6H5COX]+· is found to depend on X, while the heat of formation of the phenyl ion produced therefrom is, with one exception, independent of X. The excess energy of the benzoyl cation can be accounted for by an electronic excited state of the ion in the mass spectra of benzoic acid, benzaldehyde, benzamide, methyl benzoate and possibly benzophenone; the benzoyl cation is not excited in the mass spectra of acetophenone and benzoyl chloride.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210071215
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  • 8
    Electronic Resource
    Electronic Resource
    Substituent effects in mass spectrometry - II. The effect of substituents on the dissociation of para and meta disubstituted benzenes (1972)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 6 (1972), S. 1377-1382 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of substituents on the activation energy for primary dissociation processes in the molecular ions of mono- and para and meta di-substituted benzenes has been examined. Where the daughter ion retains the substituent group, variation of the energy of activation derives from a combination of the effects of substituents on the ionisation potential of the molecular ion and the appearance potential of the daughter ion. An equation relating the energy of activation for the fragmentation of the molecular ion of a mono-substituted benzene to that of related para and meta di-substituted benzenes is presented.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210061214
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  • 9
    Electronic Resource
    Electronic Resource
    Substituent effects in mass spectrometry - III: Substituent effects in the dissociation of the molecular ions of para and meta substituted benzoic acids (1973)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 7 (1973), S. 295-303 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of substituents on the electron-impact-induced fragmentation of the molecular ions of para and meta substituted benzoic acids has been examined. The substituent is observed to exert an effect on the ionisation potential of the molecular ion, on the appearance potentials of the primary daughter ions and on the amount of H/D scrambling in the molecular ion of the carboxyl-d1 analogues prior to the loss of hydroxyl therefrom. The energy of activation for the loss of hydroxyl from the molecular ion is in general dependent upon the nature but not the position of the substituent, while the amount of H/D scrambling in the molecular ion of the carboxyl-d1 derivative is dependent upon both the nature and the position of the substituent. No correlation of the relative ion abundances with σ+ constants was observed. The results are consistent with the molecular ions of each compound having a dissimilar energy distribution, which could arise either by different energy transfers from the electron beam to the molecule or by the participation of different isolated electronic excited states (or similar states but to varying extents) in the dissociation of the molecular ions.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210070308
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  • 10
    Electronic Resource
    Electronic Resource
    The mass spectra of benzamide and thiobenzamide (1971)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 5 (1971), S. 525-530 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectra of benzamide, thiobenzamide and their N-d2 analogues have been studied In addition to fragmenting by simple bond cleavages the molecular ions dissociate partly from their imide forms. Equilibration or ‘scrambling’ of ortho ring hydrogen atoms with amide hydrogen did not occur in benzamide but such exchange must take place in the thiocompound whose fragmentation behaviour is very complex. Neither labelled compound produced the label-retaining benzoyl (thiobenzoyl) cation which has been the subject of much interest in the mass spectrum of O-d1 benzoic acid.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210050504
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