Ammonia and methane chemical ionization mass spectra of methotrexate and its amide and ester analogues

1985 ◽  
Vol 12 (1) ◽  
pp. 11-18 ◽  
Author(s):  
H. T. Andrew Cheung ◽  
Bruce N. Tattam ◽  
David J. Antonjuk ◽  
Deborah K. Boadle
Keyword(s):  
Mass Spectra ◽  
Chemical Ionization ◽  
Ionization Mass ◽  
Methane Chemical Ionization

The hydrogen and methane chemical ionization mass spectra of some formate esters

1976 ◽  
Vol 54 (13) ◽  
pp. 2029-2037 ◽  
Author(s):  
Alex. G. Harrison ◽  
Chun Wai Tsang
Keyword(s):  
Mass Spectra ◽  
Chemical Ionization ◽  
Methyl Formate ◽  
Ethyl Formate ◽  
Rate Coefficients ◽  
Enthalpy Of Reaction ◽  
Ionization Mass ◽  
Relative Importance ◽  
Methane Chemical Ionization ◽  
Fragmentation Reactions

The H2 and CH4 chemical ionization mass spectra of formate esters up to the butyl formates have been determined. Deuterium labelling of the ester and deuterated reagent gases have been used to establish reaction mechanisms. The major fragmentation reactions of the protonated molecular ion are[Formula: see text]Reaction (a) is the dominant fragmentation for methyl formate, (b) is the dominant fragmentation for ethyl formate, while (c) is the dominant fragmentation for higher formate esters. The results show that the relative importance of the fragmentation routes cannot be predicted from the enthalpy of reaction of ground state HCO2R.H+ but are determined by the fragmentation rate coefficients averaged over the appropriate internal energy distribution of the excited HCO2R.H+ ions.

scholarly journals Discrimination of structural isomers of amphetamine using carbon dioxide negative-ion chemical ionization mass spectrometry

1997 ◽  
Vol 13 (2) ◽  
pp. 151-161 ◽  
Author(s):  
Kevin B. Thurbide ◽  
C. M. Elson ◽  
P. G. Sim
Keyword(s):  
Carbon Dioxide ◽  
Mass Spectra ◽  
Chemical Ionization ◽  
Negative Ion ◽  
Ionization Mass ◽  
Structural Isomers ◽  
Mass Spectral ◽  
Negative Ion Chemical Ionization ◽  
Spectral Behaviour ◽  
Carbon Dioxide Plasma

The negative‒ion chemical ionization mass spectra of a group of structural isomers of amphetamine have been studied using carbon dioxide as the reagent gas. Characteristic and reproducible differences are observed for each member of the set implying that this technique offers a means of distinguishing among groups of amphetamine isomers. Characteristic adducts to the molecular ion are observed in the form (M–[H]+[O]) and (M–[H]+[CO2]). Descriptions of some fragments are given based on the mass spectral behaviour of a set of analogue compounds and the results of oxygen-18 labelled carbon dioxide reagent gas experiments. Contents of the carbon dioxide plasma and their impact on various analytes is also discussed.

The monomeric metaphosphate anion in negative-ion chemical-ionization mass spectra of phosphotriesters

1984 ◽  
Vol 106 (23) ◽  
pp. 6877-6883 ◽  
Author(s):  
Seymour Meyerson ◽  
Donald J. Harvan ◽  
J. Ronald Hass ◽  
Fausto Ramirez ◽  
James F. Marecek
Keyword(s):  
Mass Spectra ◽  
Chemical Ionization ◽  
Negative Ion ◽  
Ionization Mass ◽  
Negative Ion Chemical Ionization

Negative chemical ionization mass spectra of polycyclic chlorinated insecticides

1972 ◽  
Vol 6 (11) ◽  
pp. 1171-1181 ◽  
Author(s):  
Ralph C. Dougherty ◽  
John Dalton ◽  
Francis J. Biros
Keyword(s):  
Mass Spectra ◽  
Chemical Ionization ◽  
Ionization Mass ◽  
Negative Chemical Ionization

Isobutane chemical ionization mass spectra of lanthanide perfluorinated .beta.-diketonates

1974 ◽  
Vol 46 (6) ◽  
pp. 726-728 ◽  
Author(s):  
T. H. Risby ◽  
P. C. Jurs ◽  
F. W. Lampe ◽  
A. I. Yergey
Keyword(s):  
Mass Spectra ◽  
Chemical Ionization ◽  
Ionization Mass
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